HP 7942 Service Manual

HEWLETT-PACKARD

HP

7942

AND

HP

7946

DISC/T

SERVICE

APE

DRIVES

MANUAL

CERTIFICATION

Products, have Packard taining

Hewlett-Packard's the

National

Bureau's

The ments

materials,

been

provided

specifications.

to

this

order

Bureau

calibration

Hewlett-Packard

of

FAR 52.246-15.

parts, in

is

calibration

facilities.

and

accordance

Actual

on

file

of

Standards

Quality

services

inspection

and

available

measurements

Program

with

to

the

furnished

all

extent

satisfies

on

applicable

and

test

for

examination.

are

traceable

allowed

the

this

order

Hewlett-

data

by

require-

per-

to

the

rlin-

.:~

HEWLETT

PACKARD

The main and subsequent.

part

7942

DISC/T

PRINTED: FEB 1 987 Prin ted in

of

this manual applies directly to

Refer

to Appendix A

for

In addition to the standard models, this manual covers

the

SERVICE

AND

APE DRIVES

Manual

Microfiche

U.S.A.

serial numbers prefixed

following options:

part

no.

part

no.

Serial Number Prefix

HP

7942

and

OPTIONS COVERED

FOR U.S.A. ONLY

MANUAL

7946

07942-90903

07942-90803

07942-90903

HP

7946

Disc/Tape

2614

and prior.

01

5 and 550.

E0287

Drives with serial numbers prefixed

2615

The Federal Communications Commission (in 47 CFR 15.838) has specified lowing notice be brought to

FEDERAL

the

attention

of

the users of this product.

COMMUNICATIONS COMMISSION

RADIO FREQUENCY INTERFERENCE

STATEMENT

Warning: strict been specifications interference ticular by lowing measures: ment the prepared Problems".

004-000-00345-4.

This

equipment

accordalllce

type

install~ltion.

turning

away

dealer

by

with

test.~d

and

in

Subpart

ill a

residential

the

equipment

reorient

from

the

or

3,uthorized field

tllte

Federal

This

booklet

generates

the

manufacturer's

found

to comply

J of

If

this

equipment

off

the

receiver;

Communications

is

available

and

with

Part

15 of FCC

installation.

does

and

on,

the

receiving

plug

the

equipment

service

representative

from

P.O.

uses

radio

frequeucy

instructions,

the

limits

Rules,

which However, cause

user

antenna;

Commission

the

HEWLETT -PACKARD COMPANY

BOX

there

interference

is

encouraged

relocate

into a different

for

U.S.

Government

39

BOISE,

energy

may

cause

for a Class B

are

designed to provide

is no

guarantee

to

radio

to

try

the

equipment

additional

helpful:

"How to

IDAHO

interference

computing

to

correct

branch

suggestions.

Printing

83707,

and

if

not

installed

to

disc/tape

that

interference

or

television

the

interference

with

respect

circuit.

The

Identify

Office, WashingtoD,

U.S.A.

radio

reasonable

reception,

to

If

necessary,

user

and

television

drive

the

may

Resolve

that

used

properly,

in

accordance

protection

will

not

which

by one

receiver;

the

user

find

the

Radio-TV

DC

the

reception.

against

occur

can

be

or

more

move

should

following

Interference

20402.

fol-

that

is,

in

It

has

with

the

such

in a par-

determined

of

the

fol-

the

equip-

consult

booklet

Stock

No.

PRINTING HISTORY

New editions incorporate all update material since sued between editions, contain additional and revised information user. The date on

First Edition Second Edition Third

Edition .

..

the

title page changes only when a new edition

FEB 1985

AUG

1986

FEB 1987

the

previous edition. Updating Supplements, which are

to

be incorporated into

is

published.

the

manual

by

is-

the

The information contained in this document

HEWLETT-PACKARD MATERIAL, MERCHANTABILITY AND FITNESS FOR A liable for errors contained herein ing, performance

This document contains proprietary part

of

Hewlett-Packard

COREFILE-PARCORE

INCLUDING, BUT NOT LIMITED TO,

or

this document may be photocopied

Company.

MAKES NO

or

for incidental or consequential damages in connection

use of this material.

information

is

WARRANTY

NOTICE

subject to change

OF ANY KIND WITH

PARTICULAR

which

is

or

reproduced

protected by copyright. All rights are reserved. No

without

THE

PURPOSE.

without

notice.

IMPLIED WARRANTIES OF

REGARD

Hewlett-Packard

the

prior

written

with

the

TO THIS

shall not be

furnish-

consent of

11

PREFACEI

This publication provides field service

HP

7942

consists of a

an

integrated

in a similar manner.

This publication

• Section I - Contains a general description of

• Section

• Section V - Supplies and parts in the

• Section

• Appendix number

• Tape Drive - Consists of a Tape Drive Service Manual. This tion

for

disc/tape

II

- Provides references to

III --Describes the operating principles of

IV

--

VI

--

A-Contains

prefix

the

tape drive portion of

24-megabyte

drive. The

is

divided into

Contains servicing

step-by-step

disc/tape

Lists and illustrates

2614

and prior.

the

drive.

removal

information

disc drive and a tape drive combined in a single desktop cabinet to form

HP

7946 consists of a

following parts:

the

CS/80

information

removal and replacement procedures for field replaceable assemblies

the

field replaceable assemblies and parts in

and

replacement and relaceable parts for

the

disc/tape

for the

the

disc/tape

Instruction Set commands applicable to

the

for

the

drive.

HP

55-megabyte

drive.

disc/tape

7942

drive.

manual

and

HP

7946 Disc/Tape Drives. The

disc drive and a tape drive combined

the

disc/tape

the

disc/tape

provides detailed service

drive.

drives

drive.

with

informa-

serial

iii/iv

CONTENTS

Section

GENERAL

I

INFORMATION

Introduction Documentation Related

Manuals

Options

Ch

a r

act

e r i s t

il

c s

Section

CHANNEL

Introduction CS/80

Transaction Real

II

INTERFACE

......

Instruction

Time

Commands

Structure

Complementary General Purpose Diagnostic Transparent

Commands

Messages .

Hewlett-Packard

HP-IB Communications Channel Management

Paralll~l

Poll

Universal

Message

Structure

.

Set

Commands

Interface

Device

Clear

..

Bus

Page

1-1 1-1

1-2 1-2 1-2

Page

2-1

2-1 2-1 2-1 2-1

2-9 2-9 2-9 2-9

2-12 2-13 2-13 2-13 2-13

Section

THEOR

III

Y OF

Introduction Disc

Drive

Disc Format

HOC

peA-AS

HOC

Internal HP-IB Data RAM Microprocessor Microprocessor DMA Read/Write Data

Data/Control

Control/Status Control/Status Control/Status

OPERATION

Introduction

.........

Data

........

Bus

.

Architecture

........

.

Address Data

Gate Array Data

Bus

Interface

Data

Read

Write

Bus Bus Bus

Bus Bus Strobe

Strobe

Page

3-1 3-2

3-4

3-6 3-6

.

3-7 3-7 3-7 3-7 3-7 3-7 3-7

3-8 3-8 3-8

v

CONTENTS (continued)

Control/Status Select Read/Write Data

Request

Da

ta

St

robe HP-IB Microprocessor HP-IB Channel Sel Self DMA RAM EXEC DOC 0 EPROM DOC Address Clocks

ROM Buffers

Typical

DOC

HOC/DOC

DOC/Disc Controller

Disc

Phase-

Latch DMA Clock Write

Disc

Input Output Disc Microprocessor Microprocessor/PLA Clock Head-Disc

Interface

Address

Status

f Tes t Swi

Test

Display

Ga

te

Array

...........

EPROM

1 E

PROM

Multiplexer

And

Sw

i t c h . . . . . . . . . . . . . . . _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

HOC

PCA-A2

Control/Status Read/Wri Receiver/Driver Transceivers

HDA Self-Test GPC DOC PUPO

Drive

Actuator

.................................................

Commu

Drive

Desc r

Register Err

0 r s

Register

Controller

Loc

ked

...................................................

Handshake Cont

Generator

Precompensation

A1

Drive

Buffers

Drivers

Drive

Generator

Module

Address

..............

Data

Bus

In/Data

In/Da

ta

IC

.....

Switch

...

tches

IC . . . . . . . . . . . . . . . . . . . . . .

. . . .

..

.........................................

..................................

........................................

Control

Transaction

n i

te

IC and

ipt

Register

Loop

.............................................

A1/DDC

.....

Logic

cat

ion

Data

Bus

........................................

..........................

A1

Communication Register

ion

PROM

...........................................

Reg

i s t e r

...........................

IC

....................

IC

rol

.........................................

Control

..........................................

Data

and

PLA Control

...........................................

..........................................

Bus

.

Request

St

robe

.,

................

.......................................

. . . . . . . . . . . . . . . . . . . . . .

......................

....................................

.....................................

..................

and

.....................................

.......................

.....................................

.......................................

......................................

....................................

Communication

.....................................

Out

......

Ou t ........

Address

Decode Logic

Signals

Buses

.............

..........................

. . .

.....................

.......

......................

........................

............................

..............

.

..............

.

..............

. . . . . . . . . . . . . . . .

.

..............

.

..............

.

..............

.

.........

.

.........

.....

.

, . . . . .

.

.....

3-8 3-8 3-8 3-8

3-8 3-8 3-8

3-8

. . . . .

3-9 3-9

3-9

. .

3-9

....

,3-10 . .

.

. . . . . . . . . . . . . .

. . . . . . .

.

. .

3-10 3-10 3-10 3-10 3-11 3-11 3-11 3-11 3-12 3-12 3-12 3-12 3-12 3-12 3-12 3-13 3-13 3-13 3-13 3-13 3-14 3-14 3-14 3-14 3-15 3-15 3-15 3-15 3-15 3-15

vi

CONTENTS (continued)

Recording Read/Wri Read

Preamplifier/Write Servo Servo Spindle

Air

Filtration Actuator Spindle Spindle Spindle

Speed Speed Checker Motor Brake Relay and Relay

Actuator

Demodu

Mode

Select

~Iode

Seek

Velocity Tachometer Slclpe

Current

On-Peak Power

Inverter Track--Follow Off-Track

Seek Operation

Restore

Read/Wri Head

SelE!ct and

Read

Chain Ampli f Differential

Wri

te Line Receiver

Transition Write Write

Sel f test

Power Supph'

AC

Input

Swi

tch-Mc)de

Power-On Reset

Medium

te

Heads

Head

........

Preamplifier

Moto r ......

Lock

Driver Control

Servo

la

Control

to r .....

Switch DAC

Selector

Inverter

Detector

Amplifier

.....

Mode

Detector

to

Track 0 Operation

t.e

Data Channel

Control

............

ier/Signal

Chain

........

Generator Current Fault

......

A4

Circuits

Supply

....

............

.

IC

. .

Components

.

.,

. .

.....

Logic .

Condi

Line

Driver

.

....

.

Source

Detector

.

Driver

.

tioner

. .

IC

Driver

..

3-15 3-16 3-16 3-16 3-17 3-17 3-17 3-17 3-17 3-17 3-17 3-17 3-18 3-18 3-18 3-18 3-18 3-19 3-19 3-19

3~19

3-19 3-19 3-19 3-19 3-19 3-20 3-20 3-20 3-20 3-20 3-20 3-20 3-20 3-21 3-21

3-21 3-21 3-21 3-22

3-22

Section

SERVICE

IV

INI4'ORMATION

Introduction Service FRA

Tools

Locations

Page

4-1 4-1 4-2

vii

CONTENTS (continued)

Cable Connections Signal

Power

Signal

Distribution

Notation Block Diagram Power Supply

HDC

PCA-AS

Self

Test

Self-Test

A4

...

....

Controls Tape Drive Tape Drive Disc Drive Se

1 f T

est

Sw Self-Test DISPLAY

Internal

Sel

f Test

Self-Test

Display

RESULTS

Diagnostics

...........

Subtests Self-Test

Fault/On Line Self-Test Request Request

Run

Time

Error

External

Amigo

Cancel Test

Exerciser

Clear

Transaction

HP-IB

..

. .

FAULT BUSY

Indicator

FAULT/ON

i t c h

Switch

Error

Reporting

Indicator

Display Status Status

and

Fault

........

(AMCLEAR)

Channel

....

.....

Example

(CANCEL)

(CHANNEL) Channel Independent Clear Describe Perform Output Exit Output Output Help Initialize Update Device Request Perform Read-Only Output

Spare

Output Spare Table

Logs

Selected

Internal

Error

Program

Fault

Media (INIT

Status

Run

Sector

(CLEAR

LOGS)

Unit

Diagnostics

Rate

Test (EXIT) Log

(FAULT

Information

Logs

(PRESET)

(REQSTAT)

Error

Log

(RUN

(SPARE)

(SPARE Output Device Table Perform Servo

Set

Unit

Test

Number

(SERVO)

(UNIT)

Perform Write-Then-Read

Troubleshooting

Disc Drive Maintenance

Tape Drive Maintenance .

LINE

Indicator

.

...

. .

Reporting

.

Clear

(CICLEAR)

........

(DESCRIBE)

Log

.......

LOG)

(HELP)

MEDIA)

....

Rate

LOG)

.....

........

TABLE)

(TABLES)

......

Error

(DIAG)

(ERT

. .

Test

Rate

.

LOG)

(RO . .

.

Test

ERT)

(WRT

ERT)

4-2 4-2 4-2 4-2 4-2 4-2 4-3 4-3 4-3 4-3 4-3 4-4 4-4 4-4 4-4

4-5

4-S 4-6 4-6 4-6 4-7

4-8

4-9 4-9 4-9

4-9 4-10 4-10 4-10 4-10 4-10 4-10 4-10 4-10 4-10 4

-11

4-11

4

-11 4-11 4-11 4-11 4-11 4-11 4-11

4

-11 4-11 4-11 4-11 4-12 4-12

viii

CONTENTS (continued)

Section

REMOVAL

Introduction Preparation Removal And Replacemen t

Top EPROM FRA5 Front U1-FRA1 (Tape

Fan UO-FRA4 UO-FRA1 UO-FRA2 U1-FRA2 (Tape

Section

REPLACEABLE

Introduction Ordering

Appendix

REMOV

V Page

AND

REPLACEMENT

For

Service

ShroUid

Ki

(HDG

Panel

...............................................

LED

Cable

VI

.......................................................

t s

.......................................................

PCA-A5)

......................................................

Drive

(Power (Disc (Disc

Supply Drive Drive Drive

Removal

PARTS

Information

A

AL

AND

.....

REPLACEMENT

.

...............................................

.................................................

Assembly

DDC DDC

...............................................

A1)

A1) PCA-A2) PCA-A2)

......................................

A4)

....................................

......................................

......................

...............................

.

...........

.

..............

.

.......

.

........

....

.

5-1 5-2

.

5-2

.

5-2

.

5-2

.

5-3

.

5-3

.

5-3

.

5-4

.

5-5

.

5-5

.

5-6

.

5-6

.

5-7

Page

6-1 6-1

Page

Introduction Preparation Removal And

Top EPROM FRA5 Front U1-FRAl (Tape Fan UO-FRA4 UO-FRAl UO-FRA2 U 1 -FRA2 (Tape

Appendix

For Replacement

Shroud

Ki

ts

(HDC

PCA-A5)

Panel

...........................................................

(Power

(Disc (Disc

A

REPLACEABLE

Introduction

Ordering

Appendix

Information

B

SER VICE NOTES

Service

......................................................

.....................................................

Drive

Supply Drive Drive Dr

i ve

..............................................

................................................

Assembly

Assembly Assembly DOC DOC

A1)

A1) PCA-A2) PCA-A2)

.....................................

A4)

...................................

.....................................

PARTS

.....

.

A5-1 A5-1

.

A5-2

.

A5-2

.

A5-2

.

A5-3

.

A5-3

.

A5-3

.

A5-4

.

A5-5

.

A5-5

. .

A5-6 A5-6

.

Page

A6-1 A6-1

Page

B-1/B-2

ix

ILLUSTRATIONS

Figure

Transaction

Hewlett-Packard

Disc Recording Format

Track Recording Format Disc/Tape Disc

Drive,

Disc

Drive,

Disc

Drive, Drive,

Disc

Front

Rear Panel

P8

Field

Power UO-FRA4 UO-FRA4

FRA5

FRAl

FRA2 Disc/Tape Cabling Diagram Disc

Panel

Signal Signal Signal

Replaceable

Distribution,

(HOC (Disc Drive (DOC

Signal

Structure

Interface

Drive,

Self-Test Source (Sheet 1 of 3) Source (Sheet 2 of 3)

Source (Sheet 3 of 3)

(Power Supply Assembly A4), Layout and Cable Connections (Power Supply Assembly A4),

PCA-A5), PCA-A2),

Block Diagram Block Diagram Functional Functional Functional

Self-Test

Al),

Distribution

Block Block Block

Display

Assembly

Cable Assembly

Layout and Cable Connections

......

Bus

Signal

Diagram, Diagram, Diagram,

(FRA)

.

Lines

(Sheet (Sheet (Sheet

Locations

Wl

Test

1 of 3) 2 of 3

Points

3)

of 3)

and

Voltages

Page 2-10

2-11

· 3-5

· 3-6 3-31/3-32 3-33/3-34 3-35/3-36 3-37/3-38 3-39/3-40

4-12 4-13 4-21 4-22 4-23 4-28 4-29 4-30 4-31 4-32 4-33

4-34 4-35/4-36 4-37/4-38

Order of Disassembly

HP

7942/HP

HP

7942/HP

Disc/Tape

Order of Disassembly

Disc/Tape

x

7946 7946

Drive,

Cable

Major Assemblies

Exploded

Interconnections

View

.....

.

5-11/5-12

5-8

5-9/5-10

·

6-3 A5-8 A6-3

TABLES

Tables Disc Drive Device

Disc Drive HP-IB Universal HP-IB Message

list

of Mnemonics

Host Dependent

Self-Test

Characteristics

Command

Summary

Utilities

Definitions

Command

Structure

Controller

Subtest Disc Drive (Unit Disc Drive Fault Diagnostic

Code

Error List

Summary

Disc/Tape Drive Abb

rev

ia

Code

t ion s

list

.........

o'f

Manufacturers

Disc/Tape Drive Abbreviations Code

list

.........

o'f

Manufacturers

.....

Formats

.....

List

0)

Self-Test

......

Condition

.........

Replaceable

.

Replaceable

.

(Unit 2)

Subtest

List

.

Parts

.....

Parts

.....

Page

1

-3/1-4

2-2 2-9

2-12 2-12 2-14

3-23

.

List

4-14 4-15

4-20

4-24 4:-27

6-2 6-4

.

6-5/6-6

A6-2 A6-4

A6-5/A6-6

xi

SAFETY

CONSIDERATIONS

GENERAL tion must

safety markings

-

- This product

be

WARNING

and

instructions before operation.

SAFETY SYMBOLS

Instruction product will be

symbol

the

user to

tion

manual

the

product

Indica tes hazardous voltages.

Indicates

WARNING

The hazard. It calls procedure not

correctly hered to, could result in personal injury. Do WARNING cated

conditions

stood

and

familiarization

manual

when

it

refer

in

against damage.

earth

(ground) terminal.

or

practice

performed

not

sign

met.

documenta-

with

symbol:

marked

is

to

order

sIgn denotes a

proceed beyond a

until

are

with

necessary for

the

instruc-

to

protect

attention

which,

or

the

indi-

fully

under-

to a

the

this

if

ad-

BEFORE product power source according to figuration

If

this former connected to

source.

SERVICING

APPLYING

is

configured to

instructions provided in this manual.

product

make sure

is

the

POWER

match

to be operated

that

earth

terminal

WARNING

Any servlcmg, tenance' must trained

Adjustments manual power supplied to protective

Energy

may,

sonal injury.

Capacitors still be has main

or

be

performed

personnel.

may be

available

if

contacted, result in

charged

been disconnected

power source.

adjustment,

repair

described in

covers

inside this

after

- Verify

the

input

with

the

common

of

of this

only

by

performed

the

product

are

at

many

product

the

from

available

power

an

autotrans-

terminal

the

main

main-

product

service-

this

with

while

removed.

points

per-

may

product

the

that

power

the

main

con-

is

CAUTION sign denotes a

CAUTION

SAFETY class I earthing ground must be provided source to power cord, it

is the secured against

xii

EARTH

product

terminal. An un

likely

product

The hazard. operating procedure which,

or

damage to

or all

proceed beyond a un

fully understood

and

the

product

or

supplied power cord set. Whenever

that

the

must be made inoperative

any

if

adhered to, could result in

of

til

the

GROUND - This

is

provided

protection

unintended

It

calls

attention

or

practice

not

correctly

or

destruction

the

product. Do

indica ted conditions

and

with

interruptible

from

the

input

wiring terminals,

has been impaired,

operation.

performed

CAUTION

met.

is

a safety

a protective

safety

main

to

of

earth

power

and

an

part

not

sign

are

be

To avoid a the

proper

the

specified type (normal blow,

time

delay, etc.)

replacement.

To

install disconnect device. Then, using a small bladed screw driver, fuseholder until either into

the and fuseholder by pressing ward until

it

fire

hazard,

current

or

remove a fuse,

the

cap

the

cap

end of a properly

cap. Next,

fuseholder

and

then

locks in place.

rating

must

power cord

counterclockwise

releases.

insert

cap

turning

fuses

be

used

from

turn

rated

the

into

the

cap

it clockwise

with

and

for

first

the

flat-

the

Install

fuse fuse

the in-

of

GENERAL INFORMA TION

-

[TI

1-1.

The

Drives are medium performance, random access,

data and consists of a drive

an

sists

combined in a similar manner. In this manual,

less otherwise specified, "drive" refers to both

HP

The and (5.l2-inch)

Each disc surface employs one movable head to service its

lowest disc in

prerecorded

precise positioning

Head positioning

tuator

Mechanical and contamination protection for

discs, heads, and

a sealed head-disc module. The head-disc module

includes a

which supplies clean

throughout the module.

The tape drive

removable

lengths are available: 150 feet (16.7 megabyte) and

600 feet (67 megabyte). The tape drive functions

as a back transfer megabytes per minute. (The actual rate read as well The tape drive

1/4-inch

HP

INTRODUCTION

Hewlett'-Packard 7942 and 7946 Disc/Tape

storage devices designed for use

medium sized computer systems. The

24-megabyte

combined in a single desktop cabinet to form

integrated disc/tape drive. The

of

a 55-megabyte disc drive and a tape drive

7942 and

24-

is

-after-write

disc/tape drives.

HP

7946.

and

55-megabyte

four non removable

discs, respectively, for storage media.

data

tracks. The bottom surface of

the

servo

data

of

the

is

accomplished by a

and closed loop servo positioning system.

the

rotary

slelf

-contained air

is a data

1/

4-inch

-up

device for

rate

for back

host dependent.) The tape drive includes a

capability for

as

data

recovery and automatic sparing.

is

cartridge tape drives contained in

disc drive and a tape

disc drives employ two

stack contains continuous

which

tape cartridge. Two tape

-up

compatible

is

used

read/write

actuator

air

filtration

and equalizes

storage device utilizing a

the

disc drive. The

is

approximately two

data

with

small

HP

7942

HP

7946

con-

130-millimetre

to

ensure

heads.

rotary

is

provided by

system

temperature

data

transfer

verification,

with

existing

other

un-

the

ac-

the

Also included in Interface supply.

The drive contains and a functions of tomatically by the host or by a switch on drive. green/red failure occurs, information on the cause failure can be determined by viewing a numeral display on is

to a and power supply), followed by field replaceable sembly or assemblies within Details

The drive cabinet. Accessories available include a height stand -alone cabinet designed to hold drive and rack mounting ment

1 -

The documentation provided in this publication divided into two parts. The first part, H P

and

(Sections I through disc drive and tape drive are combined in a single cabinet to form Information provided includes circuit description, servlclng details, removal and replacement procedures, and replaceable parts information. Detailed information on the disc drive theory operation, service information, and replaceable parts by the documentation for

Bus

fault-finding

Go/no-go

unit

of

subtest failures are also provided.

other

rack

is

2.

DOCUMENT A TION

7946

is

also provided. The second part, identified

liT

the

drive are a

(HP-IB)* controller and a power

internal

system which exercise key

the

drive. Self test

at

power on and can also be initiated

test results are indicated by

indica tors on the f ron t panel.

the

rear

level (disc drive, tape drive, controller,

is

packaged in a stand -alone desktop

desktop stack modules. A

the

drive in a standard EIA

also available.

Disc/Tape

an

APE DRIVE" tab, contains service

the

Drives

VI)

provides details of how

integrated disc/tape drive.

tape drive.

Hewlett-Packard

self

-test

is

performed

the

rear panel

panel.

Fault

the

identified unit.

Service

diagnostics

au-

of

the

If

of

the

2-digit

isolation

as-

desk-

the

kit

for

equip-

7942

Manual,

the

a

is

of

*Not just

computation system.

IEEE-488,

but

the hardware, documentation and support

that

delivers the shortest

path

to a

1-1

General

Inf

orma tion

7942 and 7946

Note: The two parts of

fit

will

binder,

in a 1

part

no.

equivalent binder may be used.) A

cover and spine insert kit, 07942-90909, publication for

the

which identifies

as

the

HP

7942 Disc/Tape Drives, the

9282-0502

binder.

the

publication

1/2-inch

9282-0502.

part

service

manual

and 7946

is

available for

3-ring

(An

no.

the

1

-4.

OPTIONS

The following options are available for

Option 015. For selector switch set

non-U.S. shipments. Voltage

at

factory for

operation.

Option 550. Deletion of

the

HP 1083 3A HP-IB

Interface Cable Assembly.

the

drive:

230-Vac

1-3.

RELATED MANUALS

For operating and installation instructions, refer to the

H P

7942

and

7946

Disc/Tape Manual, Environmental Manual,

information,

Programming

part

no.

refer

Manual,

no.

09742-90901,

Requirements

5955-

3456. For instruction set

to

the

part

for

CS/80

no.

additional servicing information,

CS/80

no.

External

5955-3462.

Exerciser

The HP

Reference Manual,

7942

Disc/Tape Drive CE Handbook

Drives

and

Disc/Tape

Instruction

5955-

3442. For

refer

and

HP 7946

is

part

Owner's

the

Site

Drives

Set

to

the

part

no.

07942-90905.

1

-5.

CHARACTERISTICS

Characteristics of the

physical dimensions

listed in table

disc/tape

and

power requirements, are

1-1,

drive, including

Disc/Tape Drive Characteristics. Detailed specifications for c/tape

ments, are listed

Requirements

no. the

Service

tics of

drive, including environmental

in

Site

for

5955-3456. disc/tape

Manual

the

tape drive.

Disc/Tape

This publication

drive. Refer to

for specifications

Drives Manual,

Environmental

is

supplied

the

H P 9

and

characteris-

the

dis-

require-

part

with

I44A

1-2

SAFETY

Table

1-1.

Disc/Tape Drive Characteristics

General Information

7942 and 7946

Meets

UL CSA

POWER Specified Voltage

Frequency: Typical

Typical

all

recognized

certified

REQUIREMENTS

(true

Current

Power:

applicable

to

UL

to

CSA

Source

(selected

RMS):

(true

safety

47B.

C22.2

115V

230V

RMS):

standards

No.

by

range;

47.5

115V

230V

115V

230V

of

IEC

143 and

rear

100V, 115V, 120V,

(inclusive

220V, 240v,

tolerance

to range;

range; range;

range;

panel

66

No.

154.

VOLTAGE

tolerance

range

Hz

1.50A

O.BOA

120W 120W

3BO

single

is

and

IEC

435.

SELECTOR

single

phase, 1Bov

phase,

range

to

switch)

is

90V

(inclusive

264V)

to

132V)

SIZE/WEIGHT Height: Width: Depth: Net Weight: Shipping

Weight:

20B

325

2B5

15.B

19.6

nun nun nun

kg kg

(B.19 (12.B

(11.2

(34.B

(43.3

in. in.

in. lb) lb)

) ) )

1-3/1-4

CHANNEL

INTERFACE

-

QIJ

2-1.

Interface through

hardware commands The following paragraphs discuss CS/

HP-IB.

CS/80

no. CS/80 the

2-2.

The and for Instruction of their Command CS/80 lows a host within in formed or Drive Utilities.

Reference

details.

2-3.

A tween device (the disc drive) over a given (HP-IB). transaction: command, execute, transaction the indicating by structure, disc drive relative

INTR~ODUCTION

to

the

disc/tape

Hewlett-Packard

and

the

CS/80

formulated

80 commands. Also provided

For

full details of

Instruction

5955-3442.

instructions apply

H P

9144A

CS/,BO

increase in capabilities of

mass storage devices has emphasized

efficient

Set increases

channel

firmware

logged. Utilities

TRANSACTION

transaction

disc drive,

the

operations between disc memories

associated host computers. Table

Summary, provides a

instructions.

the

disc drive. Utilities

which

and

the

Manual,

a system host

Three

begins

the

host. Figure 2 - 1 ill

and

operating

to

each phase.

Set

For

Service

INSTRUCTION

channel

The

computer

allow

results of such tests

are

Refer

part

is

a logically complete

phases

when a command

and

ends

status

of

shows

the

states and

drive

is

Interface

Instruction

for

mass storage devices.

is

CS/80,

Programming

information

to

the

tape

Manual,

communication.

to

STRUCTURE

computer

when a reporting

the

Part

both

the

efficiency

summary

CS/8 0 Instruction

access special utilities

are

error

rate

listed in

the

no.

may

transaction

ustra

relationship between

table

External

5955-

and a peripheral

occur

and

tes

the

channel

accomplished

Bus (HP-IB)

Set, a set of

the

an

overview

refer

Manual,

on how

drive

II,

Installation.

host computers

The

2-1,

routines stored

tests

to

be examined

3462,

operation

during

report. A

is

received by

transaction

types of

to

part

refer

SET

the

need

CS/80

and

speed

Device

of

Set

to

be

per-

2-2,

Disc

Exerciser

for

channel

each

message

is

accepted

activity

of

the

to

and

all

al-

full

be-

the

A

unit

is

a separately addressable device (disc drive). A volume dressable portion of given unit.

2-4.

REAL

Real

time time. These commands host/

device transactions. One

tary

commands

in

order

time

Real cate

and

2-5.

COMPLEMENTARY

Complementary date

programmable states in programmable states

set unit, set address, set block displacement, set

return

retry

set

Rotational These commands

Time,

messages,

When a complementary

embedded

meters plementary

duration complementary

meters or conditions

complementary until

power-on plementary Therefore, equal command

used

for though porarily override this value

complementary of 256 bytes (for 1 sector).

TIME

commands

to

modify

commands include: locate

write,

and

addressing mode, set length, set

time, set release, set

Position Sensing (RPS) window size.

General

or

they

within

or

conditions established by

command(s)

of

the

commands to

at

power-on,

the

entire

may

give

an

entire

some special case commands could

the

storage media

COMMANDS

are

optimized

are

may

precede a real

the

operation

cold load read.

COMMANDS

commands

define

may

Purpose, or Diagnostic

may

another

current

command, however, sets

command occurs.

volume. A

it a lise

sequence of transactions,

command

are

characteristics such

be included

stand

alone.

command (or commands)

command,

are

command. A

until

the

alters

Power-on

length

stand-alone

til

to set a

entity

is a separately

for

used most

or

more com pie

time

of

that

and

used to set

the

disc drive.

burst

status

altered

their

value

same

the

resets all

default

is

of 1 kbyte

with

"current"

mask,

within

only

stand-alone

stand

set value

defaulted

an

within

execution

often

men

command

command.

read,

or

upThe

mode,

and

Real

command

the

para-

that

com-

for

the

para-

-alone

com-

values.

Set

Length

to

tem-

embedded

value

ad-

in

lo-

as:

set

is

the

or

to

be

al-

a

-

2-1

Channel

7942

and

In

terf

7946

ace

Table 2

-1.

Device

Command

Summary

LOCA

FUNCTION:

OPCODE:

FORMAT:

LOCA

FUNCTION:

OPCODE:

FORMAT:

LOCA

FUNCTION:

TE

AND READ (REAL TIME)

Locates

mits

No

variables

TE

AND

TE

AND VERIFY (GENERAL PURPOSE)

WRITE

Tranfers

dress

No

variables

Instructs section

the

data

(REAL TIME)

data

specified

the

of

data

to

the

or

parameters

from

by

or

parameters

device

to

indicated

the

ensure

host.

host

target

to

perform

by

that

the

for

storage

address.

an

it

target

internal

can be

address

beginning

verification

read.

and

at

trans-

the

ad-

of a

OPCODE:

FORMAT:

SPARE

FUNCTION:

OPCODE:

FORMAT:

BLOCK

No

variables

(GENERAL PURPOSE)

Gives

sparing

<00000110>

P1 = sparing

S = 0 T = 0 T must S must

the

skip

retain equal 1 for equal 0 for

or

device

the

block

<OOOOOSOT>Pl

mode

spare

data

parameters

permission

indicated

byte

tape

disc

to

by

the

S = 1 T = 1

operation operation

become

target

jump

do

not

temporarily

address.

spare

retain

data

busy

while

2-2

Table

2-1.

Device

Command

Summary

(continued)

Channel

7942

In

and

terf

7946

ace

COLD

L.OAD READ (REAL TIME)

FUNCTION:

OPCOIJE:

FORMAT:

REQUEST

FUNCTION:

OPCOIDE:

FORMj~T:

RELEASE

FUNCTION:

Used

by

the

host

environment from a more

No

variables

ST A TUS

(DIAGNOSTIC)

Instructs status

No

(GENERAL PURPOSE)

report.

variables

Releases

the

or

device.

to

bootstrap

parameters

device

parameters

primitive

to

return

itself

state.

(in

into a higher

an

execution

operating

message)

the

OPCOIDE:

FORMAT:

RELEASE

FUNCTION:

OPCODE:

FORM,AT:

No

variables

or

parameters

DENIED (GENERAL PURPOSE)

Prohibits

No

variables

the

device

or

parameters

from

releasing

itself.

2-3

Channel

7942

and

Interface

7946

Table 2

-1.

Device

Command

Summary

(continued)

SET

ADDRESS (COMPLEMENT

FUNCTION:

OPCODE:

FORMAT:

BLOCK

FUNCTION:

OPCODE:

ARY)

Used

to

set

the

value

addressing

16

10

17

10

<0001000T> <

T

=

address Single 3-vector

mode.

00010000 00010001

mode

vector

format:

2 2

P1

format:

DISPLACEMENT

Adjusts

by

the

target

parameter

of

the

target

020

8

021

8

> - - - - <

(0 = single

6-byte P1-P3 = P4

= head

P5-P6 =

(COMPLEMENTARY)

address

P6

vector; binary

cylinder

address

sector

by

the

>

address

field.

address

1 =

number

address

number of

and

3-vector)

blocks

to

define

the

indicated

FORMAT:

SET

LENGTH (COMPLEMENTARY)

FUNCTION:

OPCODE:

FORMAT:

<00010010> <

Parameter

Defines

format:

the

<00011000> <

Parameter

format:

P1

> - - - - <

6-byte,

binary

number of

P1

) - - - - <

4-byte,

number

bytes

P6

>

signed,

in a data

P4

>

unsigned,

two's

binary

complement,

transfer.

number

2-4

Table

2-1.

Device

Command

Summary

(continued)

Channel

7942

In

and

terf

7946

ace

SET

UNIT (COMPLEMENTARY)

FUNCTION: OPCODE:

FORM,AT:

INITIA l"E

FUNCTION: OPCODE:

FORMAT:

Used

32

10

33

10

47

10

<0010YYYY>

YYYY = unit

UTILITY

Directs

48

10

49

10

5010

<001000XX>

xx

Pl =

There can be

number and

to

specify a specific

00100000 00100001 00101111

2 2 2

number (1111

(DIAGNOSTIC)

the

device

00110000 00110001 00110010

2 2 2

<

=

execution 00 = no

execution

01 = device

10 = device

utility

number up

content

040

8

041

8

057

8

to

perform

060

8

061

8

062

8

>

Pl

< n

message

will

receive

will

send

(device

to 8 bytes

of

these

unit

20

16

21

16

2F

16

device

30

16

31

16

32

16

parameter

qualifier message

execution

specific)

in

bytes

within

controller)

one

utility

bytes

execution

message

the

parameter

is

determined

the

device.

routine.

>

message

field.

by

The

Pl.

INITIA l"E

FUNCTION:

DIAGNOSTIC

Directs

tic

the

routine.

OPCODE: FORM,AT:

<00110011> < Pl <

Pl-P2

=

loop

P3 = diagnostic

NO OP (COMPLEMENTARY)

FUNCTION: OPCODE: FORM,AT:

Causes

No

the

variables

(DIAGNOSTIC)

device

to

perform

parameter

section

device

to

or

parameters

disregard

P2

number

one

<

the

internally

P3

>

message

defined

byte.

diagnos-

2-5

Channel

7942

and

In

terf

7946

ace

Table

2-1.

DESCRIBE (GENERAL PURPOSE)

Device

Command

Summary

(continued)

FUNCTION:

OPCODE:

FORMAT:

INITIALIZE

FUNCTION:

OPCODE:

FORMAT:

Directs

No

the

variables

device

or

parameters

to

return

MEDIA (GENERAL PURPOSE)

Initializes unit.

<00110111> P1 = initialize

Options

CWZ

CWZ CWZ

all

the

<OOOOOCWZ>Pl < P2

options

for

disc

media:

000

Retain

both

(secondary) 001 010

Retain Retain

factory

no

data

byte

spares

information

fields

factory spares

spares

(f

of

(primary)

only

0 r

CE

use

the

about

currently

and

only)

itself.

selected

field

SET

RPS (COMPLEMENTARY)

FUNCTION:

OPCODE:

FORMAT:

P2

= Block

Sets

data is

time-to-target

transfers.

not implemented.

interleave

<00111001> <

TIME TIME

time-to-target

1

2

window

The

TIME

size

byte

and

command

1>

in

window-size

is

accepted

<

TIME

2 >

in

hundreds of

time

intervals

but

the

microseconds

RPS

for

RPS

function

2-6

Table

2-1.

Device

Command

Summary

(continued)

Channel

7942

In

and

terf

7946

ace

SET

RETRY TIME

FUNCTION:

OPCODE:

FORMAT:

RE~LEASE

FUNCTION:

OPCODE:

FORMAT:

(COMPLEMENTARY)

Sets

amount of time

<00111010> <

P1-P2 =

retry

time

available

P1

in

number)

(COMPLEMENTARY)

Def

ines

how

a dev

ice

request.

<00111011> <T2000000>

T

2

Suppress

Release

release

automatically

tens

wi

11

timeout

for

read and

>

P2

of

milliseconds

respond

during

to

idle

seek

(16-bit

an

time

in

te

retries.

binary

rnal

release

SET

BlJRST

FUNCTION:

OPCODE:

FORMAT:

(COMPLEMENTARY)

Activates

60

10

61

10

and

00111100 00111101

deactivates

2 2

<0011110T> <

T 0 Only

the

terminator

T

P1 = Number

All

burst

bursts

of

mode

256-byte

074

8

075

8

>

P1

last

burst

(EOI

are

tagged

is

deactivated.)

burst

3C

16

3D

16

is

on

HP-IB)

segments

mode.

tagged

with

the

in

with

message

each

the

burst

message

terminator

(If

P1=0,

2-7

Channel

7942

and

Interface

7946

Table

2-1.

Device Command"Summary (continued)

SET

ST A TUS

FUNCTION:

OPCODE:

FORMAT:

VOLUME

FUNCTION:

OPCODE:

FORMAT:

MASK

Provides

the

<00111110> <

The

to

paragraph

1

= masked

(COMPLEMENTARY)

selective

status

message.

Pl

bit

positions

the

bit

positions

2-45

in

error

Selects a specific

64

10

01000000

2

<01000YYY>

masking of

> - - - - - - - <

in

the

parameter

in

the

CS/80 Programming Manual.

volume

on

error

status

the

P8

bytes

message.

currently

conditions

>

(Pl-P8)

Refer

selected

reported

correspond

to

unit.

in

SET

RETURN ADDRESSING MODE

FUNCTION:

OPCODE:

FORMAT:

YYY

= volume number

Specifies

the

parameter

72

10

<01001000>

the

01001000

address field

TTT = addressing

000

single-vector

001 = 3-vector

2

mode

(COMPLEMENTARY)

format

of

the

(single

status

or

3-vector)

message.

returned

in

2-8

UTILITY OPCODE(S) ALLOWED*

(hex)

32 32 32 32 32 30,32 30,32 30,32 30,32 30 30 31 32 32 32

MICRO OPCODE

(hex)

CO c4 C5 c6 C7 c8 C9 CB CC CD

CE F6 F6

BF F7

Table

2-2.

UTILITY

READ READ READ READ READ

INITIATE INITIATE INITIATE

INITIATE CLEAR PRESET WRITE READ SERVO READ

Disc Drive Utilities

PERFORMED

FULL DRIVE RUN ERROR FAULT

SECTOR

TABLES

TIME

DATA RATE LOG

TEST

PATTERN READ

ONLY

RANDOM RANDOM

ERROR READ

LOGS

DEVICE

SERIAL

NO.

TEST

SEEK

TIME

BY

ERROR

DATA

ERROR

RATE

ONLY

THE

LOG

ERROR

RATE

TEST

ERROR

DISC

TEST

DRIVE

LOG

RATE

Channel

7942

TEST

Interface

and

7946

*

OPCODE OPCODE OPCODE

2-6.

GENERAL

This

command

low

the

host to

ing characteristics

tegrity. These commands are

commands

time"

the

by of purpose commands are: locate block, release, release denied, describe, ize media.

2-7.

Diagnostic commands host replaceable assembly level. Some commands allow

protected access to variables the cause tests to be a specific commands commands. Initialize diagnostic, initialize utility, and

host unless

the

drive for a varying period

DIAGNOSTIC COMMANDS

in

isolating problems

device (such as

request status

PURPOSE COMMANDS

group includes commands

area

may

determine

or

and

it

error

performed

of

the

be modified by

are

device

to

ascertain storage media

not

therefore

is

willing

are

storage media. Diagnostic

all diagnostic commands.

should

to

in

tended

in

or

information), while others

within

the

data

executes

30

executes

31

executes

32

which

type

and

considered "real

not

relinquish control

of

time.

and

verify, spare

and

to assist

device to

maintained

the

device,

complementary

al-

operat-

in-

be issued

General

initial-

the the

by

or

on

utility

utility utility

with receive

send

2-8.

TRANSPARENT

Transparent

types

of

channels

vironments.

by

the

device command quence.

the part

2-9.

-execution

Transparent

CS/80

no.

5955-3442.

HEWLETT-PACKARD

INTERFACE

The

Hewlett-Packard provides a separate mits components terface performed cabling connects all controllers system in parallel.

devices (see figure 2-2).

transfer

functions

is

needed to

no

message. message.

message.

MESSAGES

commands compensate

and

differences

Transparent

firmware

Instruction

commands

and

-reporting commands

Set

Programming

BUS

Interface

standardized

of commands

of

a system on

for

within

the

connect

method

and

16

each system

component

the

and

other

for

in

operating

are

intercepted

modify

signal lines.

system.

the transaction are

explained

Bus (HP-IB)

of

connecting

The

HP-IB

data

between

component

so

only passive

devices

different

en-

normal

se-

Manual,

per-

the

The

in-

are

The

cable

of

the

in

2-9

Channel

7942

and 7946

Interface

TRANSACTION

PHASE

CO~MAND

Q

(0

EXECUTION

G

@

REPORTING

(1)

Logical Machine idle in command

(2)

Host sends command message.

@

CHANNEL

ACTIVITY

COMMAND

EXECUTION

REQUEST

(IF

APPLICABLE)

A

EXECUTION

MESSAGE

'I

(IF

APPLICABLE)

REPORTING

REQUEST

.A

REPORTING

MESSAGE

'It

MESSAGE

-ready

CD

COMMAND-READY

@

ACCEPT

AND

NOTE:

o

BEGIN

@

REQUEST

(1)

CO~PLETE

RECIEVE

G

COMPUTE

@

REQUEST

@

SEND

VALIDATE

LOGICAL

STATE IF

HOST

EXECUTION

DATA.

TRANSACTION

REPORTING

ONE-BYTE

state.

UNIT

~HINE

12

IF

REQUESTS

OF

MESSAGE

OR

ACCOMPLISH

MESSAGE

REPORT

OPERATING

STATE

COMMAND

GOES

TO

COMMAND

REPORllNG

COMMAND

(IF

OF

COMMAND

STATUS

(QSTAT)

REPORTING

IS

INVALID.

MESSAGE.

APPLICABLE)

~SEND

COM

AND

ACTION)

OR

DATA.

(3)

Logical Machine accepts

to

execution state.

(4)

Unit

begins execution of command.

(5,6)

If

command involves

unit

completes execution

(7)

Execution message

(8)

Unit

completes execution

receives

data

If

through

and

verifies command. If command

not, Logical Machine moves

data

transfer,

(6).

is

established

if

of

command.

channel module. If not,

message.

(9)

Logical Machine computes completion status

QST AT, complete status set

(10,11) Logical Machine requests

(12) Reporting message

(1

3)

Logical Machine sends 1 - byte reporting message

is

action. Host must send request

into

reporting

established.

command

request status.

to

reporting state.

Logical Machine requests

command involves a

If

command involves

unit

of

data

completes action called for

transaction. Pass/Fail status IS set

message.

(QST A T)

for complete status

is

valid, Logical Machine moves

an

execution message.

transfer.

data

transfer,

unit

in

indicating Pass/Fail status

report

(20 bytes).

If

not,

sends

or

command

into

of

trans-

2-10

Figure 2

-1.

Transaction

Structure

Channel

7942

In

and

terf

7946

ace

DATA

A (8

SIGNAL~NES)

<....,..

..

..-

---

..

..-

..

--

..

..-

..

..-.

..

..-.

.......

\/

TALK.LlSTEN AND

The

Hewlett-Packard certain installation of

1 Processing disc drive

The

7 metres

rules which must be followed for successful

the

metre

per

HP-

Unit

(CPU)

is

1 equivalent load.

CPU adheres to an HP

of

HP-IB

I

V

J J J

II

DEViCE

A

ABLE

TO

CONTROL

disc drive. Cabling

IB

load. Typically

is

cable between

nearest device connected

BUS

HANDSHAKE

TRANSFER

~

>'

DEVICE

ABLE

TALK

LISTEN

Figure 2-2.

Interface

7 equivalent loads

standard

to

it

and 1 metre

OR

DATA-BYTE

CONTROL

(3

SIGNAL~INES)

fI

8

TO

AND

~

I

\

'-./

~

BUS

>'

II

DEVICE

ABLE

LISTEN

ONLY

Hewlett-Packard

Bus (HP-IB) has

is

limited to

the

Central and

the

which allows

the

CPU

and

the

of

cable

between each additional device. The maximum

is

configuration

per

HP-IB

eight devices (not including CPU)

channel

or a maximum of 15 metres

or

15 equivalent loads.

The eight transfer a byte-serial, sage transfers three Ready For ted (NDAC-L). The

Data

I/O

(DIO) lines

of commands, data,

bit-parallel

are

asynchronous, coordinated by

handshake lines:

Data

(NRFD-L),

other

are

and

manner.

Data

Valid (DAV -L),

and

five lines

reserved for

other

messages

Data

and

Not

Data

are

the

in

mes-

Not

Accep-

for bus

management.

Information sequential control (DAV-L, sequence can be has been completed. proceed as fast than

allowed by

is

transmitted

NRFD-L

as

on

the

data

of

the

and

NDAC-L). No step

initiated

three

until

handshake lines

the

Information devices can respond, the

slowest device presently

lines

under

in

the previous step transfer

but

can

no faster

ad-

GENERAL

(5

.~

C

TO

INTERFACE

MANAGEMENT

SIGNA,

1

I

~

I

r

\ J

~

Interface

I

DEVICE

BUS

LINES)

'1

II

D

ABLE

TO TALK ONLY

Bus Signal Lines

...

DI01-L

THROUGH

DATA

INPUT

...

DAV-L -DATA NRFD-L -NOT NDAC-L -NOT

IFC-L

-INTERFACE

ATN-L

-ATIENTION SRQ-L -SERViCE REN-L

-REMOTE

EOI-L -END

jOUTPUT

VALID

READY DATA

ENABLE

OR

IDENTIFY

DI08-L

LINES

ACCEPTED

CLEAR

REQUEST

dressed. This permits several devices same message byte concurrently.

Devices connected to

teners, Controllereach (A dresses on device

the A TN

the devices

of

TN -L)

at

data

or

controllers (refer to In

-Charge

the

other

line low

the

data

the

time

-L line lines. When

that

have been addressed will send

the

bus may be talkers,

(CIC) dictates

devices by setting

and

sending lines. Addresses of

system configuration. While

is

low, all devices

the A TN

receive data; all others ignore

can

Several listeners only one

talk

a

is

L

talker

address

low), all

is

other

be active simultaneously

can

be active

pu t on

the

at

data

talkers will be

unaddressed.

Interface

The face system

Remote Enable (REN tween two ming

data

The End

cate

the

In addition,

the

ATN-L

capable

Clear (IFC-L) line places

in a known

alternate

such

as

the

Or

Identify

end

of a multiple-byte

sources of device

(EOI-L) line

quiescent state.

L)

line

front

when a controller-in-charge

and

EOI-L

of

a parallel poll responds on

lines low,

assigned to it.

-

FOR

DATA

to

receive

table 2-3).

the

role

the

Attention

talk

or

listen

are

set for each

must

listen

- L line

the

is

data

a time. Whenever lines (while A

automatically

the

inter-

is

used

to

select

program-

panel

or

is

used to

transfer

the

HP-IB.

sequence. sets

each

device

the

DIO line

the

lis-

The

of

ad-

to

high,

or

lines.

but

TN

The

be-

indi-

both

-

2-11

Channel

7942

and

In

terf

7946

ace

HP-IB

TERM

TALKER

LISTENER

CONTROLLER

SYSTEM

CONTROLLER

DEFINITION

Any

device

tion

Any

over

device

formation devices LISTENERS

Any

device grammed between LISTENER(s)

the

over

can

or

to the

which

function

TALKERS.

that

manage

TALKER

in

being a TALKER

Any

device CONTROLLER absolute with

the

that

and control Interface

signal.

Table 2-3.

sends

HP-IB

informa-

HP-IB.

receives

the

HP-IB.

in-

Some

as

has

been

data

and

addition

proflow the

to

and a LISTENER.

functions

is

able

of

the

Clear

as

to

gain

HP-IB

(IFC)

Definitions

There

ing

a

time.

In a parallel can ceiving

at

the

The by

addressing TALKER LISTENERS.

active

at

any

is

called

(CIC) .

There

a

CONTROLLER

CONSIDERATIONS

can

be

only

information

poll

be

up

to

eight

information

same

time.

CONTROLLER

one

and

one

There CONTROLLER time.

can

The

the

CONTROLLER-IN-CHARGE

be

only

connected

one

over

the

system, LISTENERS

over

manages

device

or

more

can

be

on

the

active

one

to

TALKER

send-

HP-IB

there

re-

the

HP-

data

flow

as

a

devices

only

one

HP-IB

CONTROLLER

SYSTEM

the

HP-IB.

at

as at

2-10.

UP-IB

This section describes for

the

tions

that

(CIC)

and

the

terms

COMMAND --A

ted

over

operation.

byte)

are

face

channel. one byte) contained

UNIVERSAL that

causes all devices on

predetermined

2-4.

PRIMARY mand

is a channel

sage sequence.

COMMUNICATIONS

HP -

IB

commands, messages,

occur

between

the

disc drive.

used

in

this

parcel

the

channel

Channel

used

to

manage

Device

are

used to

within

the

COMMAND --A

interface

COMMAND

command

It

contains

the

formats

the

Controller-In

The

following list explains

section.

of

information

(HP-

IB)

relating

commands

operations

commands

control

text

the

of a command

the

function.

--

The

that

the

command

and

sequences

and

transac-

-Charge

transmit-

to

a specific

(usually a single

on

the

inter-

(usually

operation

channel

bus

more

than

and

message.

command

to

perform

Refer

pnmary I com-

begins

to

the

listen

table

mes-

are

or

talk

and

the

address

primary

an

II

unlisten

Table

command

or

un

2-4.

Universal

UNIVERSAL

COMMAND

ATN

[POO1CCCC]

P=Parity

CCCC=Command

SECONDARY

a

command drive

TEXT --The bytes required qualifying

sets

in

the

text

depending

action

information

up

text

of a particular

terminates

talk

command.

Command

Bit

Code

COMMAND

the

action

of

the

message.

of

the

on

the

can

be

or

the

message

Formats

UNIVERSAL

DEVICE

ATN

[POO101OO]

P=Parity

--

The

required

message

required

to

instructions

can

receive

device.

CLEAR

Bit

secondary

of

the

be 1

action.

further

{such as a

The

with

disc

to

The

n

2-12

Channel In

7942

and

terf

7946

ace

device command), to receive

or

read

status data,

or

write

data, to send

to

perform a specific

operation such as a CLEAR.

MESSAGE --A unique sequence

text

bytes which (for example, CIC

transmitted

the

communication

and

over the

link

the

disc drive) remains

of

command

channel

between

the

broken.

COMMAND 1vtESSAGE --A single message taining

device

programmable parameter, be executed by

all and

the

information

initiate

an

required

an

operation, set

or

set up

execution message.

to

an

operation

address a

EXECUTION MESSAGE --A single message taining all

an

operation previously set

the

information

required

up

by a command

to

carry

sage.

TRANSACTION - - A complete process tion carried tions

are message, and

a reporting message.

2-11.

CHANNEL

out

completed

and

some

over

the

channel. Some

with

only a

require

a command, execution,

MANAGEMENT

command/report

or

transac-

and

during

devices

un-

con-

up

to

con-

out

mes-

opera-

Disable (PPD) are

internal

controller. PPE occurs when

the

service from and

occurs whenever

CIC. PPD

the

states

of

the

disc drive requires

is

the

opposite

disc drive

is

disc drive

state

active (for

example, busy executing a command) or idle. A

the

Parallel Poll Response (PPR) from

the

will occur if EOI-L

2-13.

and

if

UNIVERSAL DEVICE CLEAR. A sal command devices on

a

interface inf

orma tion stored in

places

the

function. Universal Device Clear erases

the

disc drive

universal device clear

CIC asserts

the

disc drive

is

a channel command

HP-IB

to

perform a pre-determined

the

in

a known reset state. The

format

both

is

in

the

disc drive con troller

is

disc drive

A TN -

PPE state.

that

causes all

shown

Land

univer-

and

in

table

2-4.

2-14.

MESSAGE

Each message contains

er

to table 2 -

(reJ

- -

Primary I Command

STRUCTURE

the

following components

5).

(unidirectional from CIC to device)

- - Secondary

Command

(unidirectional from CIC to device)

The following techniques

the

manage

HP-IB: Parallel Poll

are

used by

Device Clear.

2-12.

parallel poll on EOI

vice can

PARALLEL

-L

simultaneously. Each device requiring

then

POLL. The CIC conducts a

the

HP -

IB

by asserting A

respond by asserting corresponding to its address. The CIC es

only

the

device one device requires service, device

with

first. Parallel Poll Enable (PPE)

requiring

the

highest priority (lowest address)

service.

the

CIC addresses

and

the

CIC to

and

Universal

TN -Land

the

DIO line

then

address-

If

more

Parallel Poll

ser-

than

the

- - Text (bidirectional)

II

- - Primary

Command

(unidirectional from CIC to device)

TN

-L

The CIC asserts A dary

commands to distinguish

during

formation. The disc drive decodes contained

in

both

the

primary

them

and

from

the

information

I and secondary commands to prepare for action specified text.

secon-

text

in

in-

the

2-13

Channel

7942

and

Interface

7946

PRIMARY

I

[ATN] [ONE

BYTE]

--Unidirectional *CIC

to

device

--Begins

message

*Addresses

device LISTEN

to or

TALK

*Universal

HEADER

[ATN] [ONE

--Unidirectional *CIC

--Set

further

Table 2-5.

SECONDARY

BYTE]

to

device

up

device

action

HP-IB

DEVICE

--Bidirectional

--Qualifying to

for

--Write

--Read

--Status

Message

TEXT

COMMAND

device

data

Structure

OR

instructions

to

device

to

CIC

to

CIC

DATA

TRAILER

PRIMARY

II

[ATN] [ONE

BYTE]

--Unidirectional *CIC

to

device

--Terminates

message

--Unaddresses device *Unlisten *Untalk

2-14

THEORY OF OPERATION

3-1.

The Hewlett-·Packard 7942 and 7946 Disc/Tape Drives are medium performance, random access, data storage devices designed for use with small and medium sized computer consists of a 24-megabyte disc drive and a tape drive combined in a single desktop cabinet to form an sists of combined in a similar manner.

The disc/tape consists of three separate units: a host dependent controller (HDC), the tape drive, structure, storage devices (disc drive and tape drive) are solidated in the HOC and drive dependent tasks are performed by two separate device dependent trollers (DOC's), one located and one in tions of the HOC include: host interface, direct memory access (DMA), error correction, control for DOC execution of commands, status monitoring, and diagnostic self dependent tasks performed select, sector formatting, seek control, ter/separator:1 and drive control and status.

The

over the

and with ture's IB completely independent bus with assoc'iated bus.

The assemblies located in the drive cabinet include a ly (peA), two device dependent controller disc drive meGhanism, a tape drive mechanism, and a power supply. The two power supply assembly are positioned side-by-side at mechanisms are mounted above. The located above the two drive mechanisms. The

INTRODUCTION

systems_

integrated disc/tape drive. The HP 7946

aSS-megabyte

data

Unit

the

common functions of the two mass

th,e

tape drive unit. The common

HOC communicates with

Hewlett-Packard

the

DOC's over the mass storage

data/control

contains

host dependent controller printed

the bottom of the cabinet and

an

8-bit

disc drive and a tape drive

storage functional

Unit

2;

the

disc drive,

1.

See

figure 3 -

in

-test

routines. Typical device

by

a DOC include head

Interface

interface bus (DC-IB). The

read/write

8-bit

5-bit

control/status

DOC PCA's and the

The HP 7942

Unit

the disc drive unit,

the

host computer

Bus

data

bus, and a

control/status

-circuit

the

HOC PCA

con-

structure

0;

and

3.

In this

con-

func-

format-

(HP-IB)

struc-

DC-

data

address

assemb-

PC

A's,

two drive

is

PCA's, power supply, and drive mechanisms are terconnected by a number of cable assemblies.

Circuits in face integrated circuit firmware in

array

gate

The applicable to

Typical seek control circuits, serializer / deserializer, and DMA circuitry.

The disc drive mechanism consists of a sealed head-disc module with spindle and motor, discs, read/write ing mechanism (actuator), and an tem. Also located in the disc drive mechanism are circuits for reading and writing, control, status control, and spindle speed control.

The tape drive assembly consists mechanism with motor, and a capstan drive motor. Mounted the

mechanism are a servo PCA PCA. The servo PCA contains control the

tape drive capstan drive motor and head per motor. The preamplifier circuitry and a write

The power supply assembly contained, PCA -mounted, switch supply.

Included in nostic self tions of the drive and indicate faults on a numerical display which

ing in

panel indicators driven by

a

controllers show drive and the tape drive. The drive has dedicated

maintenance tracks on which are logged

of some of the self tests. The in ternal diagnostics

permit off

drive, and power supply. This furnishes a quick and easy means of and subtest level. An additional troubleshooting

the

HOC PCA include

(IC),

ROM, RAM, a custom-designed DMA

IC,

and self

DOC PCA's contain

their

DOC circuitry includes drive select logic,

heads, a rotary voice-coil head position-

the

host dependent controller are

-test

the

rear panel of the cabinet. Also,

-line

fault

-test

controls and display.

drive-related

associated drive mechanisms.

read/write

routines which exercise key

is

visible

the

operating status

testing of the HOC, disc drive, tape

isolation

an

HP-IB

a microprocessor,

formatter

air

heads, a head

and a read/write

PCA includes read

is

comprised

-mode

through

the

device dependent

to

the

/separator,

filtration

actuator

of

a tape drive

circuitry

current

of a self-

of

the

unit, assembly,

in-

inter-

circuitry

sys-

servo

-stepper within

for

step-

driver.

dc power

diag-

func-

2-digit

an

open-

front

the

disc

results

3-1

Theory

7942 and 7946

of

Opera tion

aid

is

provided by a which links utility external

HP-IB with

Refer for a detailed description of of operation.

• Tape Drive Service Manual, Section III,

programs to service

the

to

Troubleshooting.

3-2.

The

disc drive assemblies

random access, mass storage devices

with

use formatted semblies respectively. In this section, both specified.

The and diameter is of prerecorded servo precise positioning of

The disc drive employs a control dent troller common functions (disc drive, tape drive) are consolidated in and DDC. host interface, direct memory access (DMA), correction, control for DDC execution mands, status monitoring, routines. Drive dependent tasks DDC involve necessary to read or opera tions incl ude serializa modified frequency coding/decoding, DMA handshaking, detection.

disc drive assemblies, unless otherwise

head-disc

uses two

used for each disc surface.

the

lowest disc in

controller (HDC) and a device

(DDC). See figure 3 -

drive dependent tasks

The

the

exerciser

channel

system host.

the

and

following source in this publication

DISC DRIVE

small

and

storage capacities

are

24 megabytes

module in

or

nonremovable discs. One

structure

common functions of

manipulation

CS/8 0 External

drive

internal

-trained

can

also be used to check

the

interaction

the

diagnostics

tape

Exerciser

personnel. The

of

the

drive theory

INTRODUCTION

are

medium

medium sized computers. The

of

and

"disc drive" refers to

the

disc drive

four

130-millimetre

The

the

stack

contains continuous

data

which

the

which consists

of

typical mass storage devices

write

is

read/write

peripheral

4.

In this

are

and

of

data

tion/

modulation

performance,

intended

the

disc drive

S S megabytes,

is

(S.12-inch)

read/write

bottom

used to ensure

heads.

of

a host

dependent

performed

the

diagnostic self

performed

the

on

the deserializa tion,

surface

mass storage

structure,

the

HDC include:

of

data

disc. These

(MFM)

and

drive

sealed

head

depen-

con-

HDC

by

error

com-

-test by stream

error

the

for

as-

the

en-

Associated

which contains a sealed electronic control circuits operate in

in

the

nals, position and over

tional speed, and

tions.

The

mass storage device, such as a

fitted

minimum connection of

up device.

The HDC communicates

over

and

ture's

DC-IB

a completely independent

bus

bus.

assembly via the

ST-S06

electrical

established by

ted as

The

disc drive consists printed dent and

power supply assembly A4. Disc drive ly A 1 side by side A2

and The cable assemblies.

Circui include a microprocessor,

mabIe read read/write DMA gate Device dependent

disc

IC. Disc drive assembly A 1 contains a sealed

disc module (R/W) driver

with

the DDC

and

conjunction

DDC to

the

HDC

with

the

with

Data/Control

contains

with The

Interface.

an

-circuit

controller PCA - A2, disc drive assembly

and

AS are

four

ts on

an

controller

heads, a servo head, read

IC's, a servo

interpret

maintain

desired track,

perform

is

capable

a suitable DOC. This facilitates,

of

additional electronic

the

cartridge

Hewlett-Packard

the

ODC's over

an

8-bit

associated

DDC communicates

data

and

mechanical

the

Shugart

industry-wide

assembly PCA - A

power supply assembly

at

the

bottom

mounted

assemblies

the

host de penden t con

HP-IB

-only

array

interface firmware

memory (EPROM),

memory (RAM), a custom -designed

IC,

controller

IC

and

with

spindle motor, discs,

is

a disc drive assembly

head-disc

read/write

and

generate

the

maintain

read

of

interfacing

cartridge

tape

with

Interface

the

mass storage

Interface

read/write 8-bit

6-bit

The

self

control/status

with

and

control

ST-506

standard

Corporation

standard.

of

host

dependent

of

the

horizontally above them.

are

connected

integrated

in erasable

-test

switches

PCA - A2 includes a

a phase-locked loop (PLL)

preamplifier

module

circuits. These

with

the

circuitry

control

read/write

precise disc

and

write

with

a second

tape

circuitry,

drive

as a

the

host

computer

Bus (HP-IB)

Bus (DC-IB).

data

control/status

the

disc drive

lines

Interface

for

disc drives

and

con

5,

device

A4

are

mounted

cabinet

preamplifier/write

together

troller

circuit

random

and

IC, a

and

PCA - AS

program-

read/write

and

sigheads rota-

opera-

drive,

with

the

back-

struc-

The

bus,

and

data

address

of

the

is

an

adap-

troller

depen-

AI,

assemb-

PCA's

by

(IC),

-access

display.

head-

rotary

a

3-2

Theory

7942

of

Operation

and

7946

voice-coil head positioning mechanism (actuator), and

air

filtration drive assembly A programmed channel, spindle speed control. Power supply assembly

a self

supplies de voltages

the

A typical operation of read, command HP-IB preted

roprocessor executes code

Ec) and EPROM directs

EPROM to execute commands necessary for

mand controls and

The

the

tuator its microprocessor which track, tion

track, read.

the the read/write disc cQntroller and HnC roprocessor via data a time, for errors. Errors using IC. fer via

IC.

The amount sembled, checked for errors, sent to is

and

-contained

disc drive.

is

performed

from

interface

by

the

firmware

management

completion.

the

nne.

nnc

is

disc controller IC

servo

represents

the

nDC

on

the

disc

The

MFM

disc passes

read

preamplifier/write

packed in to bytes. These bytes

RAM, previously assigned by

is

being assembled,

information

The

Hnc

of

data

nMA

complete,

gate

operation

of

the

components. Also located in disc

I

are

a microprocessor

logic

array

(PLA), a

circuits

Hnc

disc drive assembly via

given

control

data

exec

from

data

host computer. When

the

for

actuator

switch

the

in EPROM to

the

verifies

track.

rotates

-encoded

from

channel

IC.

the

array

-mode

and a power-on

the

as follows: The locate

host

computer

IC,

is

stored in RAM,

microprocessor. The

from

functions.

nnc

0 (disc drive) code

The

nnc

the

seek

argument,

in

the

in disc drive assembly A 1 via

and

PLA

with a stream

the

seek offset

the

locality

If

the

until

serial

the

read/write

to

Here

the

nMA

supplied by

firmware

the

continues

has been successfully read,

nnc

gate

it

is

are

RAM to

Ie

and

gives ending

read/write

servo

power supply

reset signal to

disc drive, locate

enters

the

executive

carry

out

The

exec code

0 EPROM

the

nnc

to

argument.

from

head

is

on

the

correct

data

driver

the

nnc

MFM

checked, one sector

coordinates

buffered

data

are

the

array

corrected

the

disc

the

host

the

HP-IB

until

the

unit

control

and the

and

Hnc

its

firmware

nC-IB

which

drive

of

informa-

the

stream

head

IC

PLL IC

is sent to HnC

IC.

in

the

controller

the

computer

interface

requested

in

RAM,

data

status

and

data

and

A4

which

and

read

HnC

inter-

mic-

(EX-

control

com-

bus

causes

the

ac-

pulses

Once

on

proper

sector

from

through

and

the

and

decoded

the

mic-

As

the

Hnc

trans-

as-

and

transfer

is

in in

is

at

to

the

exec code. The ending status

computer.

and

write

A locate cate

and

read operation previously described except

the

for set up same. However, from verify start controller drive once position.

Included in test routines disc drive hexadecimal display which opening in front nnc drive. The disc drive has dedicated tracks are testing power supply. This furnishes a means of subtest level. provided by a links programs External HP-IB drive

The first more detailed description of provided.

In

sheets of

each sheet lower numerals text, for example:

The

diagram

and

"Source" column

direction in which

and

head positioning operations

the

HP-IB

operation. This

moving

read/write

it

panel

PCA-Al

logged. The

the

with

disc drive

at

order

mnemonics used in

digital signals

from

IC serializer

is

determined

the

which

and

the

FAULT/ON

where

of

the

fault

disc drive

to

service

Exerciser

channel

the

a basic block

to

facilitate

the

functional

is

identified

right -hand

are

and

accompanying

operation

the

data

interface

is

the

RAM

and

channel

that

Hnc

firmware

exercise key functions of

indicate

rear

panel

shows

the

internal

HnC,

isolation to

An

system host.

circuitry

functional

the

printed

the

results of some

nnc,

additional

CS/80

internal

-trained can

and

the

diagram

disc recording

text

corner

in boxed characters

III.

are

defined

of

table

the

is

done to allow

the

of

LINE

diagnostics

External

also be used to check

is

block

by a large

3-1,

is

sent to

is

similar to

user

data

accepted

IC prior to

through

formatter,

as quickly

head

are

diagnostic

faults

is

visible

the

disc drive. Also, a

indicator

operating

of

permit

disc drive assembly,

quick

the

unit, assembly,

troubleshooting aid

Exerciser

diagnostics

personnel. The

interaction

discussed in this section,

level

block

diagram

references

diagram

numeral

of

the

functional

text

to

in

table 3

the

assembly

the

flows.

are

into

the

seek

the

data

the

nnc

and

the

as

possible

is

in the

on a

status of

and

format

identify

proper

l-digit

through

driven

maintenance

the

self tests

off

and

CS/

of

the

then

level. A

is

to

the

(figure

page. These

in

analog

-1.

host

lo-

The

the

RAM

and

to

disc

self-

the

an

by

the

-line and

easy

and

is

which

utility

8 0

the

disc

at

also

three

3-

5),

in

the

block

In

the

where

a

3-3

Theory

of

Operation

7942 and 7946

the

signal originates numeral block

Most of "-

L"

identifying

diagram

the

or "-H"

mnemonics listed in table 3 - 1 have

suffixes. These suffixes

where

is

listed,

the

followed by a boxed

sheet of

assembly

the

is

shown.

identify

functional

low or active high logic signals, respectively. nals

without

such suffixes are usually bus

or

signals.

active

Sig-

analog

at

the

inner

diameter

of

the

disc to

permit locations. Also, duplicating at

two locations reduces

data

due to recording medium failure. The 968

data

tracks This provides ers.

The

are

the

1 7 spare

tracks containing

used

user

hard

(ID) and

read/write

for

with

tracks

errors.

outer

diameter

testing

the

service

the

possibility

reading

and

968 addressable

are

used

for

writing

(OD)

at

these

information

of

loss

of

data.

cylind-

sparing

out

In addition, Section IV, Service

tains system cabling

diagrams for

3-3.

The two plated A 1 provide read/write

the

DISC

three

head. The

disc drive.

FORMAT

metal

and

discs

data

surfaces, each

fourth

Information,

signal

in

disc drive assembly

surface

is servo head for prerecorded servo data. discs in data

the

surfaces

55

megabyte version provide seven

and

one servo surface. See figure

III

Each

data

surface circles called tracks. See figure side

diameter test/maintenance tracks, 485 da test/maintenance

The two self testing reading tain

service information, including

fault

logs,

and

3-1.

The self

is

of

track,

divided

the

ta

disc

483

data

tracks,

into

987 concentric

3-1.

From

there

are: 1 self -

tracks, 1 7 spare

and

track.

test/maintenance

and

writing. These

tracks

are

run

a spare table directory. See figure

-test/maintenance

tracks

con-

distribution

with

one

used

with

a

The

four

the

out-

1 self -

used

for

also

con-

-time

are

logs,

located

Each

data sequentially-numbered tors. Figure 3 - 2 shows

32

data

track

sectors, each

IS organized

blocks of the

track

having

256 bytes

in

to smaller

data

called

format,

of formation. The beginning of each sector tified by a which cylinder lowed by ID field two-byte first

byte

pattern.

A 1 the

ID address

da

ta

address mark.

summary

A user available

7945

is

Sector

Track Head

7941 7945

prewritten

contains

and

the

and

the

head information. This ID field

data

field.

the

data characters in

both

address marks

This

is

mark

of

the

data

identification

physical sector address plus

The

beginning

field

is

called address marks. The

followed by

and

an

F 8

recording

tracks

capacity

in

the

provided below.

Oat a

Bytes

Per

256

8,129

7,929,856 23,789,568 55,508,992

Sectors

Pe

r

30,976

92,928

216,832

32

of

flagged by

is

a hexadecimal

an

FE

pattern

provided by

HP 7941

Tracks

Pe

r

968 2,904 6,776

based data

is

(I

D)

both

and

Heads

Pe

sec-

on

in-

iden-

field

is

fol-

the

unique

for

the

HP

r

3

7

3-4

Theory

7942

of

Operation

and

7946

INNER

8~METER

NUMBER

TRACKS

OF

1

SELF

+B-3

D~TA

SPARE

485

D~TA

1

SELF

LANDING

AAD

INNER

GUARD

TEST

BAND

+MAlNTENANCE

17

+MAINTENANCE

•

ZONE

.SELF

SECTOR

ADDRESS

0

1-5

6-10

11-15

16-18

19-20

21-22

23-31

FILE-FSJEFl2A

TEST

Figure

AND

NAiNTENANCE

OUTER

DIAN

ETER PRODUCT RUN

TIME

ERRO~

RffE

TEST

ERT

FAULT

LOG

SPARE

TABLE

SELF

TEST

LOC~TION

SELF

TEST

LOC~TION

NOT

USED

3-1.

Disc Recording

(00)

NO.

LOG

TRACK

CONTENTS:

INNE,

OI,AMETER

SERIAL RUN

TINE

ERRO~

TEST

ERT

F~ULT

LOG SPARE SELF

TEST

LOCATlON SELF

TEST

LOCATlON NOT

USED

Format

10)

NO.

LOG

~TE

LOG

T,6BLE

3-5

Theory

7942

and

of

Operation

7946

L

iD

I I I

SYNC

GAP'

24X 14X

4E

FlLE-fSJEF11A

3-4.

Host terface dependent

HDC

of

functions are dependent separation,

Host

is via and

Interface

Host

• A host

•

• A

•

HOC

dependent

between

controller

is also capable

a second mass storage device.)

required

consolidated

tasks (servo control, read, write,

data

dependent

the

Hewlett-Packard

with

the

Bus (DC-IB).

dependent

interface

Direct

data tion,

Firmware

memory

random

examination

and

DDC commands

• Self

-test

~----

DO

A1

ID

ADDRESS

MARK

PCA-AS

controller

the

for

in

generation, etc.) to

controller

DDC's via

controller

access

speed

for

diagnostic capabilities.

PCA-A5

host

computer

(DDC)

of

interfacing

the

HDC leaving

the

functions

via

the

access (DMA) capability.

memory for

matching

a microprocessor

and

monitor

Figure

provides

and

the

of

the

disc drive. (The

with

The

two

mass storage devices

the

interface

Interface

HDC's

with

Bus (HP-IB)

Data/Control

include:

HP-IB.

(RAM)

integrity,

buffer

error

between devices.

to

status.

REPEATED

3-2.

Track

an

in-

device

the

DDC

common

device

data

DDC's.

the

host

for

correc-

execute

32

TIMES.

(325

BYTES)

DATA

ADDRESS

MARK

Recording

The

firmware

•

THERE

Format

in

IS

NO

the ments. One segment tem

(EXEC EPROM) location (including RAM), tion terface comprise

and

between

firmware.

the

passing

DDC

The

control

storage devices (DDC

processor

firmware

is

shared between

and

the

executive

ing, each receiving

proximately takes care function firmware The

DDC's

0.5 millisecond.

of

its own task,

the

host

or

is

included

communicate

DC-IB. This bus contains data

bus

with

appropriate associated 6 completely with

associated strobes.

The

following description of cuitry, diagram, sheet scription

_

sheet

bit

control/status

independent

paragraphs the

as shown on

_ .

of

the

mnemonics used

host

the

Lf

GAP3 GAP4

ECC

4

BYTES

GAP 3 ON

HDC consists

is

the

executive

which

DMA

of

firmware

remaining

firmware

0

and

the

microprocessor

device has requested. Self

in

each

with

8-bit

provide a more

dependent

disc drive

Refer

3X 24X 16X

OD

4E

NOMINAL

LAST

SECTOR.

of

three

operating

controls resource

gate

array

messages

and

the

two

for

the

DDC

1).

The

the

two

sets

firmware

Each

set

by

of

performing

of

the

three

the

HDC

an

8-bit

control/status

read/write

strobes

address bus,

read/write

controller

functional

to table

in

3-1

the

text

4E

IC

informa-

host

segments

two

micro-

of

timeshar-

for

firmware

whatever

segments.

over

data

detailed

for a de-

and

seg-

sys-

al-

and

in-

mass

DDC

ap-

-test

the

and

bus

cir-

block

a

on

Circuits

figure

roprocessor, designed and

in

3-5)

DMA

display.

host

dependent include firmware

gate

controller

an

HP-IB

in

EPROM, RAM, a

array

IC,

and

interface

self

3-6

PCA - A 5

IC, a

custom-

-test

switches

(see

mic-

3-5.

The

of

HDC

INTERNAL

internal

the

following buses:

bus

architecture

BUS

ARCHITECTURE

of

the

HDC consists

•

HP-IB

• RAM

Data

Bus

• Microprocessor Address Bus

• Microprocessor

• DMA

•

A

brief

bus

is

3-6.

accessed by

gate roprocessor registers

prepare

Gate

Read/Write

description of

provided

HP-IB

DATA

the

array

IC

must

in

the

for

data computer. Buffers separate from

the

RAl\1

ing between

array

gate

3-7.

used for all the

microprocessor,

the

RAM

time

IC

RAM

DATA

data

and

multiplexed processor clock cycle to

the

RAM

and

array

IC has access

3-8.

MICROI)ROCESSOR ADDRESS BUS.

Data

Bus

Array

in

Data

Bus

the

function

the

following paragraphs.

BUS.

microprocessor

input

and

output

read

and

HP-IB

interface

transfers

Data

Bus

and the data

HP-IB

transfer

data

BUS.

transfers

the

RAM

the

HP-IB. The use of

so

that

in

the

microprocessor has access

in

the

other

to

the

RAM.

Bus

The

HP-IB

and

processes.

write

to

and

the

permit

rate

rate.

The

RAM

between

and

one

half

Microprocessor Address Bus points struction the interface DMA EPROM, are switch selects EPROM

DOC 1 occurs. directly to one

DC-IB

or

data

source. The circuits addressed by

Microprocessor Address Bus include

IC,

gate

array

and

DOC 1 EPROM.

overlaid on

when

Control/Status

RAM

(via

the

address multiplexer),

IC, EXEC EPROM, DOC 0

The

the

same address space.

the

DDC 0 EPROM

the

time

interval

The

microprocessor

or

two

DDC's via a

Address Bus to

mass storage units.

of

each

internal

Data

Bus

by

the

DMA

The

to

the

various

IC

in

order

from

the

HP-IB

and

the

of

the

to

Data

speed

the

Data

RAM

DOC's,

the

DMA

the

match-

DMA

Bus

RAM

micro-

DDC EPROM's

An

EPROM

or

the

DOC 1

for

DOC 0 or

can

buffer

and

operate

is

mic-

to

host

Bus

is and and

is

gate

The

in-

write

the

3-9.

MICROPROCESSOR roprocessor processor, and

the exists on a shared by array processor trol

sequences (algorithms) in EPROM trol/status roprocessor a bidirectional trol/Status

3-10.

DMA roprocessor DMA gate and

the

tween

3-11.

Read/Write from

the bus becomes the

Data/Control

the

HOC

3-12.

The

Data/Control communication DDC's. The data

buses

Read/Write

The

Control/Status

Data

Bus interconnects

the

EXEC EPROM,

DOC 1 EPROM. The microprocessor

separate

the

microprocessor and

IC.

The

bidirectional

Data

Bus includes

information

Data

Bus

buffer

Data

Bus.

DMA

Gate

GATE Array must

array

Data

read

IC, including

free-running

executive, DOC

READ/WRITE

Data

Bus

chosen DDC.

the

Read/Write

Interface

to

the

DDt's.

DATA/CONTROL

Interface

link

DC-IB

--

a

Control/Status

Data

Bus.

Data mands to a DDC such fer

of

information

it

can

medium, or of

the

DDC trol/Status trol/status

Address Bus associated

be used to

and

its drive mechanism. A

Data

Bus provides

DATA

bus

so

from

is

connected

and

ARRAY

Bus

or

write

timer

0,

and

DATA

is

used to pass

External

INTERFACE

between consists

Bus

that

it

to

or

that

is

can

capability.

The

Read/Write

the

data

which

and

the

DOC. Details of these DC -

their

associated select

the

following paragraphs.

Data

Bus

is

flows between

and

strobe lines

of

Theory

BUS.

the

Operation

7942

and

7946

The

Mic-

the

micro-

DOC 0 EPROM,

RAM

the

RAM

can

the

DMA

data

on

the

Micro-

preprogrammed

the

DOC's.

to

the

DC-IB

DATA

used

BUS.

when

to registers

the

DMA

con-

and

con-

The

Mic-

DDC's via

Con-

the

mic-

in

registers

used to sequence DOC 1 operations.

BUS.

data

to

the

HOC,

Data

Bus

portion

Bus (DC-IB)

linking

BUS

Bus (DC-IB)

the

HOC

of

two

Data

is

used to send

initiate

from

the

interrogate

is

and

independent

Bus

and

com-

the

trans-

recording

the

status

Con-

with

the

Con-

an

addressing

the

path

the

taken host IB

are

by all

computer

signals,

given in

be

gate

The

the

be-

The

and

the

of

the the

a

and

3-7

Theory 7942

and

of

Opera

7946

tion

3-13. trol/Status

CSB7-H

which tion

3-14.

Control/Status

to Data ture tion

3-15. Control/Status to Control/Status

3-16.

Control/Status

CSA 5 - H

Control/Status

used tached

3-17. which Da

CONTROL/STATUS

Data

comprise a

is

used

to

pass

between

the

HOC

CONTROL/STATUS

Read

pass bytes

to

the

Bus. These bytes will be

since

the

actual

will be passed

over

CONTROL/STATUS

Write

pass bytes

from

the

Data

CONTROL/STATUS

Address Bus, Bits CSAO-H

are

the

address lines associated

Data

to

access specific registers

to

the

DC

- Ill.

SELECT. Select signal

DOC

will respond to a given

ta

Bus

operation.

DOC 0 (disc drive).

3-18. Data comprise between on coming

3-19. OUT. Request

READ/WRITE

Bus, Bits

an

8-bit

the

HOC

the

bus

is

from

DATA

Data

Request

Out

DATAO-H

bus used

and

the

digital

the

recording medium.

REQUEST

signal req uest lines used Read/Write OAT

A 7

-H.

from

the

via

the

Control/Status

The

HOC

Data

"out"

to

the

req uest line.

DATA

BUS.

Bus, Bits CSBO-H

bidirectional

control

and

a given DOC.

Strobe signal

HOC

across

8-bit

and

status

READ

CSRS-L

the

Control/Status

STROBE.

of a DOC-status

recording

the

medium

Read/Write

WRITE

Strobe signal

HOC

to

CSWS-L

the

DOC across

Bus.

ADDRESS BUS.

Bus.

The

address lines

in

the

SEL-L

Control/Status

A low

-level

DATA

SEL - L selects

BUS.

through

to

pass

high

the

chosen DOC.

information

going

IN/DATA

In signal

DROUT-L

to

Bus

direction

DOC. A

Data

DRIN-L

are

transf

OAT

is

DOC

Bus

3-state

er

AO-H

defined

is

programmed

to

drive

Con-

through

data

bus

informa-

is

used

na-

informa-

Data

Bus.

STROBE.

is

used

the

through

with

the are

DOC's

at-

chooses

Read/Write

DATA7-H

-speed The

to

data data

and

REQUEST

and

Data

DMA

bytes

over

through

as being

a given

3-21.

HP-IB

The

HP-IB

talker

/listener

face

between

the

mass storage device. microprocessor put

and

read

and

IB

interface fers to separate

INTERFACE

interface

device. This IC provides

the

and

output

write

IC

and

from

the

HP-IB

host

by

the

processes.

to

the

various registers

in

order

the

data

integrated

data

The

to

host

bus.

The

HP-IB

talker/listener

da

ta

transfers,

interface

functions

handshake

IC

addressing, service request,

polling. HP-IB End Ready NDAC-L, L,

REN described

3-22.

The device functions. employs Firmware eludes the DOC kilobytes

3-23.

The switch an Three dress in fourth

HP-IB

Data

or

Identify

for

Service Request

-

L.

signals

I/O

Data

Interface

The

in

Table

connected

Bus

DIOI-L

EOI-L,

NRFD-L,

Clear

SRQ-L,

functions

3

-1.

Data

MICROPROCESSOR

microprocessor provides overall

The

host

an

internal

associated

the

EXEC EPROM,

DOC 1 EPROM.

with

The

0 EPROM provide

of

code.

HP-IB

opening

of

segment

ADDRESS SWITCH

ADDRESS

which

is accessible

on

the

segments allow

the

range

on

the

rear

of 0 through

switch

IC

circuit

channel

IC

DMA

The

microprocessor

(HP-IB)

is

accessed by

gate

array

in

prepare

for

data

computer.

bus

from

the

implements

of

the

HP-IB

protocol,

and

talker/listener

serial

and

to

the

through

Valid

DAV-L,

Not

Data

IFC-L,

Attention

and

Remote

of

these signals

control

dependent

8-bit

the

microprocessor.

microprocessor

DOC

0 EPROM,

EXEC EPROM

approximately

switch

to

panel

the

an

is

a

operator

of

the

HP-IB

7 to be set.

is

not

used.

is

the

inter-

and

the

IC

in-

must

the

HP-

trans-

Buffers

RAM

all

of

data

the

including

parallel

IC

include

DI08-L,

Not

Accepted

ATL-

Enable

are

of

all

controller

in-

and

the

44

4-segment

through

disc drive.

device

ad-

The

a

3-20.

DATA

Data

Strobe In signal DSIN - L signal lines tween

DSOUT-L

which

the

STROBE

are

accompany

HOC

and

IN/DATA

and

HOC-generated

the

transferring

the

DOC.

STROBE

Data

3-8

Strobe

DMA

of

data

OUT.

Out

strobe

be-

3-24.

The sor

with

of

the full) via

the

CHANNEL

channel

information

DMA

and

details

DC - Ill.

STATUS

status

block provides

gate

array

of

the

regarding

IC (DMA full,

units

connected

the

microproces-

the

current

DMA

to

the

status

not

HOC

3-25.

SELF-TEST

SWITCHES

3-29.

EXEC

Theory of Operation

7942 and 7946

EPROM

Two momentary contact pushbutton switches, cessible through openings in disc drive, allow the operator to

the

of

internal self

-test switch, labeled SELF TEST, initiates routines. The RESUL played on can read

TS,

the

other

causes

self

the

-test

operation of the switches and will

itiate the appropriate self

3-26.

SELF-TEST

DISPLAY

the

rear panel of initiate

diagnostic routines. One

the

switch, labeled DISPLA Y

self

-test

results to be dis-

display. The microprocessor

-test

operations.

ac-

the

operation

self

-test

in-

The Self -Test display consists of two 7 -segment LED's which are visible through openings in the rear panel of

disc drive. The display

is

control-

the

led by the microprocessor and provides a 2 -digi t

-test

hexadecimal readout of self

results, including the defective unit, field replaceable assembly (FRA), and subtest failure number. Information on how to in

Section

3-27.

interpret

IV,

DMA

the

self

-test

Service Information.

GATE

ARRAY

IC

readout

is

contained

The executive (EXEC)

EPROM contains

firmware which controls operation of

the

microprocessor and

interface

computer. This includes decoding

host commands, and setting up

the

with and

data

the

validating

the

HDC

the

host

transfer paths. The EXEC EPROM employs a 16k by 8 EPROM. All 16k

3-30.

DDC 0

is

used.

EPROM

The device dependent controller (DDC) 0 EPROM contains firmware which provides storage for govern operation of drive). The

processor Address information

Data

Bus.

the

on

the

pre programmed sequences which

the

DDC for

EPROM

is

sent

is

addressed by

Bus

via the EPROM switch

out

over the Microprocessor

The DDC 0 EPROM module

same address field

as

the DDC 1 EPROM.

permanent

unit

0 (disc

the

Micro-

is

overlaid

and

An EPROM switch selects the DDC 0 EPROM or DDC 1

EPROM when the time

interval

for

the

microprocessor to have access to DDC 0 or DDC 1

occurs. The DDC EPROM's. A total 28k of

0 EPROM employs two

the

available 32k

is

used.

The DMA (direct memory access) gate

array

IC

is

a custom-designed integrated circuit which performs the

DMA function for

troller. DMA

is

defined as the ability to perform

complete memory cycles

the

of IC controls RAM.

HDC microprocessor. The DMA gate

data

transfers between

It

also transfers self from the microprocessor to The DMA gate to or

an

the

DMA gate

to the RAM

array

output

array

completely

from

the

host dependent

without

-test

is

set up for

the

RAM. Once activated,

IC

performs reads or writes

transparent

the

intervention

the

host and

status information

the

self

-test

either

to

an

the

con-

array

display.

input

micro-

processor.

3-28.

RAM

The random access memory (RAM)

data

storage location for all

is

RAM

time multiplexed

transfers. The use of

so

that

is

a temporary

for one half of a microprocessor clock cycle the microprocessor has access to RAM and for the

array

gate

IC has access to RAM.

other

half the DMA

3-31.

DDC 1

The DDC 1 EPROM contains firmware for

EPROM

con-

trolling a second mass storage device.

3-32.

ADDRESS

The address multiplexer addresses to be multiplexed between

processor and the DMA gate

3-33.

CLOCKS AND

MULTIPLEXER

(MUX)

array

CONTROL

allows

the

IC.

LOGIC

the

RAM

micro-

The clocks and control logic block contains all of the

circuitry controlling

the

of

3-34.

host dependent controller.

ROM SWITCH

The ROM switch allows access to DDC 1 firmware

so ecuted. This permits the firmware to be larger the

linear address space of the microprocessor.

the

timing and operation

that

either code can be

the

DDC 0 or

ex-

than

3-9

Theory

7942

3-35.

The and required various buses of unidirectional row

3-36.

The transaction computer the drive asking for mation the validated. The command drive DDC message. The message firmware

DDC servo drive firmware IC

the array this action, a request firmware output RAM to

When a the buffer firmware buffers IC computer buffer the HOC computer's request for disc information.

3-37.

of

Opera tion

and

7946

BUFFERS

buffers

bidirectional

and

TYPICAL

following

host

HDC executive

and a buffer

disc drive

IC

buffer

transfers

HOC as to

returns

consist of a

communication

buffers

the

bidirectional

is

- -

the

and

the

computer

to

the

host. The

firmware

issues seek

and

read/write

firmware

an

input

firmware

for

an

input

for

the

channel,

the

HP-IB

RAM

buffer

is

given

to

the

HP-IB

starting

may

be transferred. The DMA gate

the

and

terminates

is

empty. The host

the

to

DOC

number

buffers

and

the

HDC.

are identified by a single

buffers

"DC

TRANSACTION

a description of a typical HOC

flow

of

disc drive. To

sends a

the

transfer

command

firmware

is

(DOC

is

received

and

circuitry. Also,

requests

channel

in RAM. When allowed to do

programs

transfer. In

is

made to

use of the DMA gate

which

data

status of

the

will

interface

is

full

the

process

interface,

the

buffer

from

the

host. This completes

of

unidirectional

which

isolation between

On

sheet

by dual arrows.

data

between

start

command

of

a sector

is

and

the

then

passed to

0)

in

the

and

the

read commands to its

from

to

IC.

of

the

computer

the

DMA gate

the

conjunction

the

transfer

data

from

that

will

with

the

transfer. Multiple

RAM

operation

transfer,

PCA-A2

provide the

the

_,

ar-

the

host

the

process,

to

the

disc

of

infor-

received by

command

form

disc drive

executive

OMA

executive

array

data

the

output

executive

to

the

when

interrogates

which

the

is

disc

of a

disc

array

so,

gate

with

IC

from

disc,

the

array

host

the

host

(HOC) over the OC level

status

•

Executes these ferring sequences.

• Performs all of stream disc. Functions include serialization/deserialization, MFM coding/decoding, transfer tion.

Circuits and and a phase-locked port decode logic, backup precompensation.

The description cuitry, as shown on diagram, sheet scription figure

3-38.

Communication takes place via (DC-IB). for be stored

•

A related the

in

circuitry

and

following paragraphs provide a more detailed

of

III.

"DC/DDC

The

passing

or

Control/Status

Read/Write

brief

description

to

following paragraphs.

commands to

them

necessary to read

handshaking,

the

DOC include a disc

includes controller

four

control, a clock generator,

of

the

device dependent

III

the

mnemonics used in

COMMUNICATION

between

the

DC-IB

control/status

retrieved. These are:

Data

the

operation

IB

bus,

high-level

into

ST-506

the

manipUlations of

required

error

detection, DMA

and

loop

registers

the

.

Refer

Data/Control

provides

Data

Address Bus

of

for

disc drive

to table

the

information

Bus

the

function

of

the

and

provides

the

HOC.

commands by

Interface

or

write

data

for this

write

Ie.

HOC

three

DOC,

manipulation

precompensa-

controller

Additional

and

disc

controller

functional

3-1

the

text

and

Interface

primary

and

of

each bus, as

is

provided in

trans-

control

the

on

register

and

for a

and

the

data

high-

data

the

en-

data

IC

sup-

IC

write

cir-

block

de-

on

DOC

Bus

buses

to

Device forms mass storage control drive:

• Accepts

3-10

dependent

the

following functions

mands issued by

controller (DOC) PCA -

high-level

structure

disc drive

the

host

in

the

used in

dependent

A2

peripheral

the

control

controller

per-

disc

com-

3-39. DRESS BUSES. All disc drive high

commands to/from

Bits CSBO-H

Address

Control

CONTROL/STATUS

and

the

Bus,

and

status

DOC via

through

Bits CSAO-H

status

information

Control/Status

CSB7

information

-H

DATA

and

through

ultimately

AND

-level

Control/Status

control

are

passed

Data

CSAS-H.

resides

AD-

Bus,

in

specific registers in

Control/Status

it

since

tual over

passes only address information. The

values sent or received from a register are sent

the

bidirectional bus since

Address Bus

Control/Status

data

Data

the

DDC. The

is

a unidirectional bus

Bus.

This bus

can be sent or received

over it.

To send

the

trol/status the Bus, trol/status

control/status

target

register

Address

register

is

Select signal

Write Strobe CSWS-L

placed on

To retrieve information, dressed signal Strobe CSRS-L register value

with

SEL-L

the

Control/Status

is

set low, and

is

placed on the

is

Bus,

SEL-L

pulsed.

information

addressed

the

data

the

Control/Status

is

set low,

is

the

target

Address

Control/Status

As

CSRS-L

Control/Status

to

with

to

be

pulsed.

register

is

Bus.

3-40.

data Read/Write DA T A 7 transferred, Data using DRIN-L,

When first byte Bus. begin is, ready to Request

DROUT-L, L, Read/Write handshake con determined by

READ/WRITE

to be stored

H.

'Vhen a command requires

the

Bus,

one byte

the

appropriate

DSIN-L,

writing

of

However,

until

the

disc has arrived

acc1ept

Out

line

it

clocking

the

Data

data

at

DROUT-L,

data

the

transfer

the

actual

DDC

data,

DROUT-L.

pulses

byte

Bus.

tin

ues

the

sector

or

Bus

is a time,

to

the

is

Data

out

at

This

un

DATA

retrieved

passed on

BUS.

DAT

and

Disc storage

is

passed over

AO-H

the

Read/W

clocked

DMA handshake lines

or

DSOUT-L.

disc,

the

HDC places

on

the

Read/Write

transfer

ready

the

Strobe

from

of

data

to

accept

target

sector). When DDC activates When

the

Out

line DSOUT-

the

HDC onto

HDC senses

DROUT-L/DSOUT-L

til

the

transfer

count

register

controller IC has been satisfied.

the

DDC,

the

Con-

written

and

Con-

is

Bus,

Select

pulsed,

through

data

to

in

or

does

data

length

in

the

ac-

is

to

Data

ad-

Read

the

Data

be ri te out

the

Data

not

(that

Data

the

disc

Theory

3-41.

types DDC. The receiver bidirectional

a

Read/Write DATA 7 of with unidirectional CSAO-H consists

RECEIVER/DRIVER.

of

receivers

and

data

Data

-H

between

the

two identical octal

3-state

of

outputs. The receiver used

input

of

through

an

octal

SCA5-H

buffer/line

drivers are employed

driver used

transmission

Bus DAT AO- H

DDC and

D-type

Control/Status

and

driver

of

Operation

7942

and

Two

to

provide a

path

the

HDC consist

flip-flop

Address Bus

Select line

with 3 -sta

7946

different

in

the

for

through

devices

for

SEL-L

te

outputs.

3-42.

sion CSB

place via for from

block signal transmission. A similar transceiver manage control status troller IC disc controller

3-43.

Communication between assembly A 1 takes place via This controller IC

The

TRANSCEIVERS. Bidirectional

of

Control/Data

7 -H between the DDC and

an

octal

asynchronous

the

controller IC

to

the

and

two-way

transceiver determines

disc

data

Bus

CSBO-H

the

transmitter/receiver

communication. A line

and

register decoder logic

the

direction

inf

orma tion to which passes

the

through

HDC takes

IC.

function

ST-

groups

DDC/DISC

506

--

control

DRIVE

is

provided

and

some additional support circuits.

Interface

and

Al

COMMUNICATION

the

DDC

and

the

ST-

506 Interface.

primarily

by

signals are divided

data. Signals

in

the

group include Head Select Bits HSO-L

HS8-L,

TRKO-L,

Ready Write

Seek Complete SKCMP-L,

Write

RDY-L,

Gate

Fault

WFLT-L,

Step STEP-L, Direction

WGATE-L,

and

Drive Select Bit

Index

transmis-

through

designed

of

is

used

to

disc

con-

the

disc drive

the

disc

into

two

control

through

Track

0

INDX-L,

DIR-L,

DSO-L.

Signals Write tial

in

the

Data

lines WMFM+,

MFM Read

data

Data

group

are

WMFM-

lines RMFM

differential

and

differen-

+,

RMFM

MFM

-.

data

from

the

When reading

DRIN-L

In

and

Data

used to handshake

data

disc,

Strobe In

into

DDC.

the

write

and

In both above, of are

the

Data

the

DDC to

activated by

Request lines signal

transfer

the

read operations described

a byte.

HDC to clock

the

DSIN-L

the

HDC from

Data

data

Data

Request

lines

the

readiness

Strobe lines

in

or

out.

are the

The

functions of

data

signals

Mnemonics.

the

ST-506

are

described in Table

Interface

control

3-1,

List

3-11

and

of

Theory

7942

and

of Operation

7946

3-44.

CONTROLLER

IC AND

REGISTER

DECODE LOGIC

The controller IC selection registers

of

external

provide additional control, management, functions. Inputs to trol/status CSA5-H, Control/

Control/Status

Status Write Strobe CSWS-L line SEL-L. The registers controlled by logic include one registers,

and components

and

register decode logic controls

the

disc controller IC

to

the

Address

Bus,

decode logic

Bits CSAO-H

and a number

disc controller which

Read Strobe CSRS-L,

PROM, four general purpose

two test registers. Details

are

provided in

the

following

and

are

through

and the

of

status

Con-

Select

decode

these

para-

graphs.

3-45.

UDA DESCRIPTION PROM. The HDA scription PROM only memory containing all necessary

to

is

a 5

describe

12-byte

programmable

of

the

head -disc module

the

information

de-

read

contained in disc drive assembly A 1 to the HDC. Each head-disc

32-byte specific information. mal operation factory

4-segment settings for HP

7945

3-46.

general-purpose read

-test

self

3-47.

purpose hardware drive for dicator via

3-48.

module described in

the

PROM has two

description fields contaInIng device

One field

and

the

other

use. The desired field

switch U 484 on

normal

operation

field

the

of

is

selected

is

DDC.

the

is

reserved for

selected

The

HP 7941

are noted in section V of this manual.

SELF-TEST

REGISTER. This

-only

register which contains

circuit

information.

GPC REGISTER. This circuit

write-only

register which performs

is a general-

control functions. The register provides the

front

DDC

outputs

ERRORS

panel

RED-L

FAULT/ON

and

GREEN-L.

REGISTER. This

LINE

for

nor-

with

switch

is

circuit

and

in-

IS a general-purpose read register which contains DDC transfer

3-49.

error/fault

inf

or rna tion.

PUPO REGISTER. This general-purpose an

overflow for DMA ing. The mnemonic PUPO represents der

/Protect

Over.

descriptions

read/write

data

and

DMA

circuit

data

is

register which acts as

transfer

sector

Protect

count-

Un-

3-50.

DISC

CONTROLLER

The disc controller IC

IC

is

a single-chip IC which provides most of the control signals to manage the ST-

506 Interface. To tions, command ers in

the Interface mand,

the

information

disc controller via

Bus (DC-IB).

disc controller carries by manipulating DMA control lines, disc drive begins when mand controller. and the run which controls recognizing

by loading

Information

head

number selected address lines. The disc controller by

an

internal

the

perform

disc storage

is

written

the

At

the

ST

- 506 In

as

needed. Operation of the

HDC initiates a

the

is

written

internal

registers in

such

as

to these registers

programmed logic

flow

of

data

commands

and

func-

into

regist-

Control/Status

end of

out

terf

the

command

ace

com-

and

com-

the

cylinder, sector,

array

(PLA)

through

the

formatting

the the

disc

with

is

chip,

the

data.

During a write from

the

Read/Write specific sector. However, before tion can begin, ca ted. The disc con cylinder position the

requested cylinder number.

is

performed to position

track.

After

which matches the cylinder, head, and sector,

a

disc controller reads parallel Read/Write an

MFM format, face to be command specified multiple sectors, cal sector must be searched for repeated. controller

After returns

The read operation tion' except Read/Write the

HDC. MFM -encoded read

the

disc controller over

RMFM-

a

generated by

lines together

The controller includes logic which provides capabilities corrections. This to

detect length

errors of

anywhere

operation, parallel

Data

the

cylinder

troller

information

the

disc controller finds

Data

Bus,

serializes it, converts

and

sends

written

that

Data

the

and

on the disc.

the

last sector

the

bus back

is

similar to

decoded

Bus

external

in addition,

function

up

within

data

Bus

and

written

the

write

and

sector must be 10-

consults its

and

compares

If

necessary, a seek

the

head over the desired

an

data

in from

it

to

the

ST-

506

If

the

process

is

written,

to

the

HDC.

the

write

data

is

sent out on

and

written

the

differential

with

a synchronous clock

data

into

is

entered

phase-locked loop

error

correction code (ECC)

data

can

error

support

data

provides the capability

to

five consecutive bits

a full sector.

is

read to a

opera-

internal

it

with

ID field

the the

it

into

Inter-

original

logi-

is

the

disc

opera-

the

RAM

in

into

RMFM+,

IC.

detection

error

in

3-12

The disc controller computes four ECC bytes for each sector and appends these bytes to the end of each data field during sector write operations. During sector reads, the disc controller computes

error

f our error syndrome bytes. These

then

bytes are tion

if

an

Error

detection

line in the logic

used to compute correction

error

occurs.

is

signaled when

goes

active. This

an

error

syndrome

informa-

error

control

status line

runs to the DDC errors register. Host firmware

data

error

can recognize a

by examining bit 5 of

the DDC errors register.

Error

correction supplied by the disc controller. When a arises,

the able to the HDC error

within the sector (error offset), and

ror

pattern

uses this information to correct

the

target sector.

is

performed by using information

data

error

disc con troller makes

that

tells:

a)

the

inf

orma tion a

location of the

b)

vail-

the

required for correction. HDC firmware

data

errors within

er-

The ECC function can be operated in a standard "generation" mode or in a

by the

GPC register. In

ECC bytes are generated by

data

applied to the

field during sector writes. Also, syndrome bytes are stored in subsequent reading upon detection

the

In

"long" mode, ECC

generated by the disc controller. Instead,

"long" mode,

the

"generation" mode, the the

disc controller and

the

disc controller for

as

selected

of a data

or

syndrome bytes are not

the

error.

user

can issue four bytes to be appended on a sector

during writes. In the

the

following the

user and are not used for syndrome generation.

"long" mode

The kout

of

data

the

ECC hardware and firmware;

used during normal operation of

3-51.

PHASE-LOCKED

The

data

separation function

is

implemented with a phase-locked loop (PLL)

IC IC.

The PLL separates

contained in the raw MFM-encoded read

"long" mode, the four bytes

field are passed directly back to

is

employed for diagnostic

the

disc drive.

LOOP IC

of

the

disc controller

the

clock and

it

data

chec-

is

pulses

data

not

sig-

nal. This signal, received from the read chain in

disc drive assembly A I,

RMFM-. The PLL

IC

passes synchronized data

labeled RMFM

+,

is

and a read clock to the disc controller IC where the

actual

data

separation and byte packing takes

place.

Theory of Operation

7942 and 7946

3-52.

LATCH

The latch in head and disc drive information which plied to the sary since the disc controller these signals. Outputs are Drive Select line

is

an

octal

D-type

ST-

506 Interface. This latch

flip-flop

IC

does

that

not

latches

is

necessupply

DSO-L

sup-

and Head Select signals HSO-L through HS8-L.

3-53.

DMA HANDSHAKE

The DMA control logic includes

with

to: interface Request signals Data

Strobe signals DSIN-L, DSOUT-L. Disc

is

transferred

the

via Bus

3-54.

drivers and receivers on

DATAO-H

CLOCK

the

DRIN-L,

to/from

through

GENERATOR

The clock generator supplies a

the

to

disc controller IC to synchronize write operations. The generator also provides a clock

input

to

the

phase-locked loop IC in

CONTROL

the

circuits needed

DMA operation; supply

DROUT-L; and accept

the

disc one byte

at

Read/Write

DATA 7-H.

5-MHz

clock signal

10-MHz

the

Data

data

a time

Data

data

separator circuit.

3-55.

WRITE

Because of MFM -encoded data,

PRECOMPENSATION

the

multiple frequency

the

transitions

content

written

of

on

the

the disc are not equally spaced. During readback, pulse crowding causes

transitions to move from

their

the

expected position. To compensate for timing shift

write

data

the

to

timing

DDC by

the

disc

and prevent this pulse crowding, is

adjusted prior to

Write precompensation data

lines and control logic external controller control

IC.

the

write operation.

is

provided in

The disc controller provides lines to

external precompensation circuitry.

These lines are used to select

the

proper delay depending upon the MFM sequence being written. Since pulse crowding does not occur in disc drive

1,

the

assembly A

write precompensation circuit bypassed. (Precompensation circuitry the DDC to ensure compatibility

is

included in

with

is

future

products.)

3-13

Theory

7942

3-56.

Disc drive assembly A 1 consists of a sealed

disc module

positioning mechanism (actuator), recording medium, motor, eluded in assembly module, servo,

The the

•

• Position

• Main

• Read

•

• Provide a

The outermost

ST -

eludes: receivers, microprocessor control logic, detection, drive selection,

The PCA, accepts +SV and control, head tion, power reset,

Interpretation perf mabIe logic is

cated

of controlled signal. MFM from

channel.

preamplifier/write

of

Operation

and

7946

DISC DRIVE A 1

containing a rotary

read/write

and

air

are

two PC A's

and

interface

components in disc drive assembly A 1

following functions:

Perform a power-on

Interpret

over

Report

the

electronics

SO 6 control

second PCA,

performs

ormed by a microprocessor

achieved by driving

track

the

and

the

desired track.

tain

precise disc

and

write

actuator,

PCA

read/write

the

actuator

array

-following

spindle

driver

-encoded

discs by means of a

Write

heads, a servo head, a spindle

filtration

AI,

control electronics.

generate

maintain

MFM-encoded

faults.

contamination

recording medium,

are

on

and

data

circuits,

moun

from

following functions: spindle speed

and

generation of control signals

(PLA). Positioning

motor

circuit

errors

driver

components. Also

external

which

self

control

rotation

packaged on two PCA's. The

the

assembly, to

signals

and

ted

power supply assembly

positioning,

clock generation.

the

actuator

servo system. Speed

is

performed

using a

data

are

IC's in

voice-coil head

to

the

contain

-test.

signals.

the

read/write

speed.

data.

free

environment

and

are

connected,

interface

an

index circuit.

under

is

the

track 0 detec-

and a program

360-

written

read/write

reported by

the

head-

in-

head -disc

read/write,

perform

heads

for

heads.

which

drivers

write

outermost

of

with a dedi-

by a Hz

to

read/write

the

in-

and

fault

A4

are

the

heads

control

phase-

reference

and

read data read

data

channel. heads, by enclosing these components in a sealed

disc module having a

The following paragraphs provide a more detailed description of ponents drive to table used

3-57. MUNICATION

The drive assembly A 1 via

STEP-L,

through WGATE-L. microprocessor or

The disc drive assembly A I via Complete Fault of these signals are the

Head Select lines HSO-L plied via control Write HS2-H, in

3-58.

The DDC via

3-59.

-

The

actuator,

and

functional

3-1

in

the

DISC

ST-

S06

Drive Select DSO-L, Head Select HSO-L

HS8-L,

ST-

S06

WFL

PLA. See sheet

logic which

Select

to

the

sealed head -disc module.

INPUT

ST

- S 06

are

input

OUTPUT

ST-S06

ly A 1 driver low level (true state) measured high level (false state), The Select line developed DSO-L.

are

is

output

Contamination

and

recording medium

built-in

the

disc drive assembly A 1

electronic circuits, as shown in

block diagram, sheet

for a description of

text

and

sheet

DRIVE

Interface

These signals are applied

Interface

SKCMP-L,

T-L,

input

WS,

the

BUFFERS

Interface input buffers.

control

output

capable of sinking 48 milliamperes

at

the

control

At/DDC

control signals

Direction

the

PLA, as shown in sheet

control signals

Track

and

Ready RDY -L. The

output

III

.

buffers

read

to

DRIVERS

directly to head select

outputs

and

Head/Select

preamplifier/write

control

the

microprocessor

signals

via open

with a maximum

driver. When

the

signals

from

protection

air

III.

CONTROL

input

DIR-L,

output

0 TRKO-L,

by

the

through

Chip

from

-collector

the

driver

are

the

Drive Select

is

achieved

filter.

III.

the

mnemonics

input

buffers

and

drivers

microprocessor or

HS8-L

Enable signal CE,

signals

disc drive

transistor

gated by a Drive

are

Write

to

either

output

are

majority

are

lines

driver

from

and

the

assemb-

drivers. Each

of 0.4 volt

driver

for

head-

com-

the

disc

Refer

COM-

to disc

Step

Gate

III

from

Seek

Write

apand

HS

I-H,

IC's

PLA

at

is

in its

is

input

the

its

off.

3-14

Theory of Operation

7942

and

7946

3-60.

MUNICATION

Data

and

face RMFM - from are driver. MFM Write

WMFM - from read/write

3-61.

Disc drive assembly A 1 employs a microprocessor and internal mands from the These operations include servo control, spindle speed control, ing.

The microproGessor consists of a single chip computer IC which incorporates processing memory input/output processor clock generator. (This generator also provides

1152-kHz

servo control demodulator and a

the

The programmed logic IC which augments

processor. Functions handled by status logic, write tion, and step control.

3-62.

SIGNALS

Signals generated by

purposes

Seek,

tion' Stop Motor, Inner Track, Servo Enable, Even In, Velocity PLA Complete, Write Fault,

Signals internal

DISC DRIVE

signals passed between disc drive assembly

the

DOC are passed over

data

lines. MFM Read

the

output

MICROPROCESSOR AND

a programmed logic

control lines of

spindle motor speed control circuit.)

Odd In, Pick,

-generated

to

the

data

channel via a line receiver.

operations. These devices receive

the

device dependent controller over

read/write,

unit

(CPU), 4 kilobytes

(ROlVl),

is

MICROPROCESSOR/PLA

within

input

to disc drive assembly A 1 include: Power

256 bytes of

lines, and a serial port. The

clocked by

and

576-kHz

disc drive assembly A 1 include:

Command, Speed,

signals include: Write Gate, Seek

to

the

AI/DDC

Data

read/write

DOC via a

Data

DOC are

array

the

ST-506

and

an

signals

array

the

operation of

fault

monitor,

the

microprocessor for control

Counter

microprocessor from

Reset, Normal

and

Ready.

DATA

the

ST-

signals RMFM+,

data

channel in

differential signals WMFM+, input

PLA

(PLA) to control its

Interface bus.

error/fault

an

data

memory (RAM),

external

for

360-Hz

is

a custom -designed

the

read/write

and

Seek Complete.

506

to

8-bit

of

9.1

the

signal for

the

PLA include

CONTROL

COM-

Al

Inter-

Al

line

the

Al

com-

report-

microcentral

program

micro-

26 - MHz

actuator

micro-

selec-

Regula-

circuitry

On Reset, Index,

0,

Track Gate, and

PLA include: Power On Reset, Fault, Write Gate,

Drive Select, Stop, Seek

3-63.

The clock genera and a generator has five microprocessor, 1152 kHz and 576 kHz for demodulator in

92.1 kHz for 360 Hz for

3-64.

Details of head-disc module are provided paragraphs.

3-65.

servo head are mounted on a by precision ball bearings. A bobbin coil, tween two voice-coil head positioning mechanism (actuator). This mechanism provides the driving force required to move ing. The magnetic field in magnets allows to be con trolled by current tuator provided to protect cause trol. When rotary zone taneously, landing zone to prevent possible damage to excessive shock during relocation or shipment. Drive plied by

3-66.

medium either

diameter al umin

there module,

surface used for prerecorded servo information.

Off

CLOCK

number

HEAD-DISC MODULE

ACTUATOR. The

attached

for

servo control circuit. Crash stops

the

actuator

arm

at

the

if

current

an

RECORDING MEDIUM. The recording

is

side of a

are two such discs in

with

At

Speed, Count

Track, On Peak, Direction In, Write

9.216-MHz

GENERATOR

of

the

spindle speed control circuit.

the

components contained in

See sheet

to

permanent

the

is

driven to a nondata head landing

inner

the

arm

the

disc drive

for

actuator

a plated

three

clock.

Complete,

tor

consists

count-down

outputs --9.216 MHz for

the

actuator

spindle speed checker circuit,

III.

the

rotary

magnets comprise a

the

rotary

acceleration of

the

voice -coil

voice coil

the

heads should a

servo control circuit to lose

disc drive

diameter

is

automatically locked over

is

the

actuator

lock driver circuit.

metal

130-millimetre

um

substrate. In

surfaces used

Not

Ready, Fault,

Internal

of

registers. The clock

servo control circuit,

read/write

rotary

arm,

arm

the

is

supplied by

is

powered down,

of

inadvertently

lock solenoid

magnetic coating on

the

inputs to

and

At

Speed.

a crystal oscillator

the

in

the

following

heads

arm

supported

-type

and

mounted

for

head position-

gap between

the

rotary

current.

malfunction

the

discs.

head/medium

subjected

(5.12-inch)

the

HP 7941,

sealed head -disc

for

data

sealed

voice

rotary

arm

Drive

the

con-

Simul-

is

sup-

and

the

the the

and

be-

the

ac-

are

the

one

3-15

Theory 7942

and

The

servo

surface

7945,

data

and

the

servo

face

of

Operation

7946

inf

of

the

there

are

one

surface

information

the

bottom

orma

tion

bottom

four

disc

is

recorded on

disc in

discs,

with

for servo

is

recorded

in

the

stack. In

seven surfaces for

information.

on

the

lower

stack.

lower

the

HP

Again,

sur-

jacent to head selection, four the the circuit

the

read/write

heads. Each

and

heads. The IC's

data

IC

provides write

read signal amplification for

channel

electronics

sealed head -disc module via a flexible

cable.

are

connected to

external

current,

to

printed-

3-67.

READ/WRITE

HEADS. The disc drive employs Winchester technology one

for

each

data

to

fly above

of

air

which acts as

The

flying

at

the

drive

is heads to the

discs

surface.

the

discs supported by a

height

inner

is

diameter

powered down,

the

landing zone

where

the

approximately

heads come to rest on

an

of

The

air

the

at

bearing

disc.

actuator

the

face.

Each

head consists of a gapped

ed

in a ceramic slider. wound are that windings detecting in

In a write current This and coa process orients ticle to store particles pass the direction. Erasing any on

In beneath intersect through duced

around

connected

the

common

the f erri

the

at

a common point

point

are

used for

or

producing a magnetic field

te

core.

operation,

current

aligns

ting

through

on

the

generates a flux field across

the

magnetic particles

the

surface

the

direction of

beneath

flux field

is a function

is

data

the

which

disc.

may

a read operation, as

a head,

the

into

the

gap in

flux field causes a voltage to be

the

windings This induced voltage cuitry of current

to define

the

disc. Each flux reversal, caused by a

polarity

the

change, generates a readback

There

ferrite

core

acts as a

both

reading

data

is

written

windings of

of

the

poles of each magnetized

the

head. The

of accomplished by have been previously recorded

the

data

magnetically stored flux fields

the

ferrite

wound

is

analyzed by

data

recorded on

age pulse.

There mounted

are

on

read

preamplifier/write

the

rotary

arm

of

read/write

heads

are thin

to

16

When

inner

ferrite

are and

core

two

the

and

center

and

by passing a

the

selected head.

contained

disc.

The

flux field as

direction

the

write

writing

surface

core.

Gap

around

the

actuator,

heads,

designed

cushion

the

heads.

microinches

the

disc

moves

diameter

the

of

sur-

mount-

windings

phased such

tap. These

writing

at

the

in

by

gap

the

writing

par-

the

of

current

over

passes

motion

in-

the

core.

read

cir-

the

surface

write volt-

driver

IC's ad-

3-68.

READ

Ie.

The read standard read/write four

heads, read

and

supply a

the

IC's

PREAMPLIFIER/WRITE

preamplifier/write

integrated

circuit

head control. The

from

or write to

write

fault

signal. Control signals for

are

supplied by

the

driver IC

designed for disc drive

IC

can the

head select

logic block.

is

The IC Binary Head Select signals decoded by ing

and WS. and

when

When applied across the

current

the

to

swings, generated by through

head

enabled by Chip Enable signal

the

IC to select the desired head.

writing

When

the

head

the

transition

WS

is

IC

is

the

drawn

of

the

inductive

is

controlled by Write Select signal

is

high,

the

write

low,

the

read mode

in

write

mode,

OX, DY lines

from

the

selected channel. Head voltage

the

switching

head,

detect

circuit

in

HS

I-H,

mode

is

differential

is

used to switch

write

current

of

are

monitored by a

the

IC.

proper head voltage swings indicates

short

in

either sence of swings will cause a (US)

output detector, the

PLA.

When

the selected head, amplified, ferential and

signal conditioner.

that

such is

in

the

drawn

from

detected by

3-69.

SERVO HEAD. The servo head only head heads. The

preamplifier

servo of

the

actuator.

half

of

the

write

current.

current

line. This line

which

will pass a

IC

is

in read mode,

OX, OY lines to

write

current

read mode,

the

Unsafe line

the

fault

constructed

output

is

the

detector.

similarly to

of

the

IC

mounted

head winding, or The absence of voltage

to flow

is

connected to

write

and

the

If

a

applied to

write

into

fault

data

is

output

read chain

fault

condition exists

the

current

and

the

head

is

amplified by a

on

the

DRIVER

is

select one

of

selected head,

and

control

CE-L.

HS2-H

are

Read-

is

selected,

selected.

current

source

write

current

Absence

an

open

an

of or

ab-

the Unsafe

the

fault

message to

read

from

the

on

the

dif-

amplifier

IC

when

will be

fault

will be

is

a read

read/write

rotary

arm

a

it

3-16

3-70. preamplifier amplifier designed for use

SERVO

PREAMPLIFIER

IC

is

a two-stage

as

a preamplifier for a

IC. The servo

differential

magnetic servo head. The preamplifier output, labeled put the the to

3-71.

three -phase brushless dc motor which spins discs motor are

SERVO+, SERVO-,

of

the

actuator flexible printed read

preamplifier/write

the

read/write

servo control demodulator via

-circuit

data

is

connected to

cable used to connect

driver

IC

channel.

SPINDLE MOTOR. The spindle motor

at

a speed of 3,600 rpm. Incorporated in

three

Hall-effect

sensors which are used

the

in-

signal lines

is

a

the

by the spindle speed control circuit to indicate which of

fourth start for timing purposes wi output

the

Hall-effect

of

track

buffer

three

phases should be driven. A

sensor in

the

motor provides a

llndex signal. The Index signal

thin

to

the

ST-

A 1 and

506

is

passed via

Interface

as Index

is

used

an

signal INDX-L.

3-72. self -contained recirculating air disc module. A separate

pressure equalization within module

3-73.

The is detects Speed signal true). activates its tuator The heads to move over

3-74.

The spindle motor solid decides which of should be drivlen to spin the motor in direction. The speed a phase-locked frequency regulator which pares a with This regulator circuit provides feedback in the

AIR

F][LTRATION COMPONENTS. A

through

a 0.3 micron

filter filter

without

the

introduction of contaminants.

ACTUATOR LOCK

actuator

energized

that

lock

is

controlled by a solenoid which

at

power-on

the

spindle motor

At

after

this time,

Pick line which

lock driver to energize

actuator

arm

is

now released, allowing

the

discs.

SPINDLE SPEED CONTROL

three

-state

the

motor

Hall-effect

aLre

input

sensor

to a ROM

spindle speed control circuit which

the

three

outputs from

of

the

360-Hz

signals from

signal from

the

three

speed control circuit such

is

maintained

at

filter

supplies clean

to

the

sealed

allows for

the

sealed head -disc

DRIVER

the

microprocessor

is

up to speed (At

the

microprocessor

in

turn

causes

the

lock solenoid.

outputs

commutator

motor

is

controlled by

the

clock generator

Hall-effect

that

the

3,600 rpm, ±

head-

ambient

the

from

the

circuit

the

proper

sensors.

to

drivers

speed of

3.6

rpm.

ac-

the

in a

com-

Theory of Operation

7942

and

7946

At

power-on,

turned

off, the microprocessor sets

signal false, causing

brake to activate. processor disables by deactivating allows

the speed regulation. The microprocessor monitors motor speed by measuring tween When cates rpm,

the

the that the

circuit by activating The microprocessor stops plication of speed control

3-75.

SPINDLE SPEED CHECKER

The spindle speed checker circuit monitors speed of frequency of motor

Hall-effect signal from sor monitors outputs down operation of

after

the

Power On Reset signal

the

spindle motor dynamic

At

the

same time,

the

spindle speed control

the

Normal Regulation line. This

spindle motor

to

accelerate

the

Index pulses from

time

the

interval

speed

between

is

within one

microprocessor enables

the

Normal Regulation line.

the

Stop Motor signal to

and

relay driver circuits.

the

spindle motor by comparing

the

Index pulses from

the

from

sensor

clock generator. The microproces-

the

At

the

speed checker

the

with a 92.1-kHz

Speed and

disc drive

the

Stop Motor

the

micro-

circuit

without

time

interval

the

spindle motor.

the

pulses

percent

the

of

speed control

spindle motor by

the

spindle

the

spindle

Counter

circuit

if

Not

the

Ready

and

speed

is

any

the

be-

indi-

3,600

ap-

the the

clock

shuts

is

determined to be outside of a predetermined range.

3-76. RELAY

SPINDLE MOTOR

DRIVER

BRAKE

RELAY

AND

The spindle speed control circuit includes a dynamic brake which brings

halt

rapid

when

the

microprocessor issues a Stop Motor signal. Signal Stop Motor activates driver which in

turn brake relay to connect the

winding of time, signal circuit, disables

3-77.

ACTUATOR

Actuator

positioning

the

spindle motor.

Stop Motor,

the

three-phase

SERVO CONTROL

and

the

spindle motor to a

causes

the

low-value

input

to

drive to

head

track

the

spindle motor

resistors across

At

the

speed control

the

motor.

following

relay

same

is

achieved on a closed-loop basis using a dedicated

is

servo surface. The servo information the

bottom surface

system employs a

an

on servo tracks On

amplitude difference between

written

track

is

realized

of

the

bottom disc. The servo

dual-frequency

at

two

different

for a data

head when

technique based

written

alternating

frequencies.

the

on

servo

3-17

Theory of

7942

and

Operation

7946

head

tracks. In operation, a continuously samples servo head, sums

produces a position

signal

track)

is

positioned exactly between

demodulator

the

two

frequencies

and

averages

error

is

linearly proportional to

amount

and

also indicates

the

signal

two

from

two signals,

(PES).

the

This PES

error

off

circuit

direction.

During

a transconductance power

drive

causes

point

tween

and

rotary

servo head

track

following,

current

the

where

the

arm

to

the

actuator

the

PES voltage

two servo tracks. Since

read/write

of

the

actuator,

is

translated

the

amplifier

actuator

to hold

heads

to all of

PES voltage

which supplies

voice coil. This

the

servo

is

zero --exactly

the

are

fixed

on

any

movement

the

is

input

head

servo head

the

of

read/write

heads.

PES

is

Signal

the

rotary

the

seek,

negative peaks

determine

voltage

rotary

The

arm

dual-frequency

also used

arm

is

PES voltage

which

track

location. Also,

is

used to

during

relatively insensitive to servo

defects. Also, servo head

a critical

The

factor

actuator

in

servo demodulator, mode select switch, digital-to-analog

of

Details

these circuits

during

a seek operation.

moving across

is

a series of positive

the

microprocessor counts to

the

determine

the

seek operation.

the

technique

azimuth

the

operation

control

converter

circuitry

(DAC),

are

provided in

the

discs

during

slope

of

the

velocity of

described above

surface

medium

alignment

of the system.

includes a

tachometer,

and

amplifier.

the

follow-

ing paragraphs.

3-78.

signal (read head combination nate signal

DEMODULATOR.

from

the

servo surface via

and

the

servo

preamplifier

of

the

frequencies recorded

servo tracks --700

is

amplified

and

The

kHz

then

SERVO+,

IC) consists

and

1020

separated

SERVO-

the

on

alter-

kHz. This

into frequencies by two identical mixer channels in demodulator. In one channel, mixed produce 124 kHz erator

attenuated

mixer channels. channels

with

576

kHz

from

kHz.,

In

the

other

is

mixed

with

11

52kHz

to produce 132 kHz. Higher frequencies

with

active low-pass filters

The

two

outputs

are

rectified, averaged,

the

from

the

clock

generator

channel,

the

from

and

fed to

700

the

clock

the

kHz

in

the

servo

the

and

(off

track

to

at

be-

rigid

the

As

and

PES

the

is

not

servo

of

two

the

is

to

1020

gen-

are

the

mixer

in-

put

of a

difference amplifier servo head tracks placement

is

Position

is

positioned exactly between two servo

(read/write

from track) causes PES to depending on amplitude

equal to PES level of 1 volt equals a displacement of proximately

100

The rectified

a

mixer channels are also fed to a summing amplifier amplifier

which

at

the

The demodulator also contains a tor. This frequency face to the

a

in

turn

the

3-79.

switch tuator (velocity) Opera tion signal from

3-80.

is

selected by

the

circuit

(1100

identify

detector

is

transmits

ST-

506 Interface.

MODE

is

SELECT

a solid

servo control

or of

the

SEEK

MODE. The seek mode

mode select switch to Seek line. This selects a which control tuator

together

system supplying drive

voice coil. These circuits include a velocity digital-to-analog slope selector,

and

inverter,

power amplifier.

amplifier. The

Error

head on track), PES

this position

go

either

the

direction of offset

the

amount

Signal

(read/write

output

PES.

When

is

zero.

of this

head

positive or negative,

and

with

of

the

offset. A

microinches.

and

averaged

supplies

input

senses

kHz) recorded on

track

coupled to

Track

-state

track

follow mode of operation.

switch

outputs

an

AGC voltage

of

the

demodulator.

the

presence of a

O.

The

Track 0 output

the

microprocessor

Zero signal

SWITCH. The mode select

circuit

which places

circuitry

is

con trolled by

track

the

in

either

from

the

and

zero

servo

TRKO-L

the

AGC

to

detec-

third

from

which

the

a seek

Seek

microprocessor.

of

operation

the

microprocessor when

the

seek position

number

of

it

switches

circuit

with

blocks

comprise a negative feedback servo

converter

current

(DAC), tachometer,

inverter, on

-peak

to

the

detector,

the

Dis-

off

an

ap-

two

the

sur-

on

ac-

its

ac-

a

3-81.

Velocity DAC.

dard

integrated-circuit

er

which

outputs servo system in response to command

3-82.

measurement ing

from

Tachometer.

the

slope

the

of

of crosses tracks. However, non

-linear

at

the

waveform. Therefore,

The

velocity DAC

digital-to-analog

a velocity

error

an

dc voltage

8-bit

microprocessor.

The

tachometer

the

actuator

velocity by

the PES signal as

the

PES voltage becomes

peaks of its triangle

at

this time

is a stan-

convert-

velocity

provides a

integrat-

the

actuator

-sha

the

to

the

error

ped

power

3-18

Theory

7942

of

Operation

and

7946

amplifier

differentiated

current

to provide

to

the

actuator

an

indication of

velocity.

3-83.

programmed by

Slope Selector. The slope selector circuit,

the

Even In signal from roprocessor, selects a PES slope polarity

tachometer

to

provide a negative

for

the

feedback.

3-84.

with In signal from of for

3-85.

operates switch between differentiated The to

3-86.

transconductance to

Current

a gain

the

proper polarity from

input

to

On-Peak

at

output

the

microprocessor to signal

Inverter.

of

± 1

and

programmed

the

microprocessor, selects a

the

tachometer.

Detector. The on

approximately

the

integrated

of

motor

the

on

-peak

current

The

3.

detector

Power Amplifier. The power

the

actuator

amplifier

voice coil in response to

which supplies

the

5 volts to

PES signal in

track

voltage input. The amplifier labeled VCMA, VCMB. The

the

by

3-87.

and

Servo Enable line from

Inverter.

is

programmed

The

inverter

with

microprocessor. The purpose

an

error

select

input verter

to

is

the

from

voltage

power amplifier. The

the

tachometer

PES (track follow mode),

amplifier

the

has a gain

signal Odd In from

of

the

correct

(seek mode)

as

selected by

select switch.

3-88.

follow mode

processor

addressed

plied via select switch the roprocessor programs voltage of

feedback

TRACK

-FOLLOW

of

operation

at

the

end

of

track

has been reached. Signal PES

the

track

-follow

through

MODE.

is

selected by

a seek operation

position

the

inverter

power amplifier. Signal Odd In from

the

inverter

the

proper polarity to provide a negative

signal to

the

amplifier.

voice coil

actuator

the

of

the

proper

current

with

inverter,

the

current

power

-peak

amplifier

detector

initiate

and

the

tachometer.

is

also coupled

crossings.

amplifier

current

an

output

lines

is

enabled

microprocessor.

of

the

inverter

polarity for

input

to

the

or

the

track-

The

the

micro-

when

of

the

to

the

input

the

to select a PES

is

mic-

Odd

the the

is

error

are

± 1

the

is

to

in-

signal

mode

the

is

ap-

mode

of

mic-

3-89.

detector monitors and provides

processor whenever

minus

3-90.

have Ready true disc drive in this state, basic loop, monitoring Motor Speed,

looking for Gate Select Step signal forces Seek Complete

If

a deactivating is microprocessor will microprocessor will set from The microprocessor will also set

a

which time cause actuator

the mance val between Step pulses

OFF-TRACK

an

1.5

volts.

DETECTOR.

the

amplitude

Off

Track

the

PES voltage exceeds plus

of

output

The the

PES signal

to

the

SEEK OPERATION. The disc drive must

RDY-L

and

Seek Complete

SKCMP-L

before a seek operation can begin.

the

microprocessor

Off

Track,

either

WGATE-L,

DSO-L. When a Step pulse

a Step

both

STEP-L

of which

pulse

are

gated by Drive

is

received,

SKCMP-L

Write

Gate

fault

condition will be issued,

received

the

information

the

actuator

moves

Step pulses

of

the

is

true

the

write

and

Write

the

actuator

is

are

actuator

and

Seek Complete goes false,

automatically

circuitry. When a Step pulse

Gate

in

not

true,

initiate

on

to

move. The speed

dependent on

a seek operation. The

the

direction

the

Direction

servo control

the

seek mode,

the

rate

of

DIR-L

circuit

at

which

received. Maximum

is

attained

is

less

if

the

than

time

39

off

-track

micro-

With

is

or

then

the

at

which

perfor-

inter-

micro-

or

the

in its

and

Write

the

false.

the

seek line.

at

will

the

seconds.

the

track

The microprocessor counts there

are no more Step pulses and crossing processor switches the roprocessor now for tion exists, timer. This

the

last track.

seek mode to

an

off

-track the

is

done

the

actuator

the

track

starts

a settling

condition.

microprocessor restarts

until

the

At

this

follow mode. The

If

off

crossings

the

time

the

servo control

timer

an

off

-track the

-track

condition cleared plus the settling time. Once this complished,

SKCMP-L.

line

3-91.

To

perform roprocessor enables cuit

and

out

of area. tuator processor will cause circuit

the

RESTORE

a restore to

moves

the

landing zone

Once

the

is

in

the

to settle

microprocessor sets Seek Complete

TO

TRACK 0 OPERATION.

track

0 operation,

the

actuator

the

actuator

into

microprocessor detects

outer

guard band area,

the

actuator

servo

over

the

outer

actuator

on a

control

data

guard

that

servo

data

until

actuator

micro-

from

mic-

and

looks

condi-

settling

is

ac-

the

mic-

cir-

area

and

band

the

ac-

the

micro-

control

track. The

is

3-19

Theory

of Operation

7942 and 7946

mIcroprocessor will set direction velocity, and track

0 signal now cause track

and

servo control

count

the

check for

circuit microprocessor will imum the RDY

3-92.

The and qualifies

nal from the

track

counter. When this

microprocessor will

-L

and

Seek Complete signal SKCMP-L.

READ/WRITE

read/write

control logic, a read

the

differential

the

read

sealed

head-disc which converts write

data

signal from DDC current driver

3-93.

drive for

IC's.

HEAD

SELECT AND CONTROL LOGIC

The head select hardware

HSO-L from enable one of four function

through

the

PLA. The

the

or

decode of

write

read/write

write labeled Chip Enable CEOSelect bits In

the

HS

I-H,

HP 7945, where two IC's are used to control

the

track

is

detected. The microprocessor will

servo control

the

track

is

locked onto

initiate

its maximum

activate

DATA

data

channel includes head select

chain

MFM-encoded

preamplifier/write

module,

the

TTL-level

the

read

and

control logic block performs a

ST-506

HS4-L

and

output

driver/read

heads,

function. The

L,

HS2-H; and Write Enable

out

with

crossings

circuit

0 signal.

until

to lock

After

track

and

is

accomplished

Drive Ready signal

CHANNEL

which amplifies

read

driver

and a write

channel

MFM -encoded

PCA-A2

into

preamplifier/write

Head Select signals

the

Write

signals from

preamplifier

and

CE 1-L;

Gate

activate

output

binary

the

IC,

the

lines

a slow

the

onto

the

0,

the

min-

and

sig-

IC's

in

write

signal

block

select

read

are

Head

WS.

seven heads, Chip Enable CEO-L selects one IC for controlling heads the

other

IC for controlling heads 4

Signals

HS

l-L,

HS2-H,

through

and

3,

WS

and

are

CE

l-L

through

input

selects

to

both

6.

0

Ie's.

amplifier/signal

conditioner stage

and a differen-

tial line driver.

a

3-95.

amplifier section DY tomatic gain control (AGC). A diode input able signal from read chain from operation. The AGC

Amplifier/Signal

input

is

amplified, filtered

of

the

amplifier, controlled by the Write

Conditioner. In the

of

the

block,

the

and

the

microprocessor, isolates

the

write

chain during a

circuit

compensates for signal

differential

subjected to

matrix

variations caused by normal differences

in

DX, au-

at

the

En-

the

write

head flying height, head characteristics, and recording medium. The AGC feature

which

circuit

maintains switching between heads. Following AGC, nal

is

filtered, differentiated,

crossing detector which converts the

analog signals

Circuitry

in

into

logic-level pulses.

the

signal conditioner portion

block prevents noise in

f rom prod ucing false zero crossings. This achieved by applying crossing detector to a gating tively screens

3-96.

Differential output driver from

3-97.

to

the

WRITE differential DDC

and

out

signal

the

line

is

ST-506

driver

CHAIN. The

MFM -encoded

converts the

spurious pulses caused

Line Driver. The conditioned

coupled via a

are

suitable for transmission to

the

read

of write

chain

preamplifier/write

circuitry transition generator, a write

fault

detector.

includes

an

AGC hold

AGC control when

the

sig-

and

input

to a

zero-

differential

of

the

analog

the

output

circuit

Interface. The

labeled RMFM+,

write

data

to a

the

write

input

of

the

which

by

noise.

differential

output

RMFM-.

chain receives

data

from

differential

driver section

signal

zero-

effec-

line

lines

the

signal

driver IC's. The

includes a line receiver, a

write

current

source,

and

is

a

3-94.

differential preamplifier preamplifier/write

READ

CHAIN. The read

current

DX, DY from

portion

driver

of

IC's. This signal represents magnetic transitions seen by it

flies over Whenever tion'

the The read signal and converts

the

magnetic recording medium.

the

head passes over a magnetic

preamplifier

chain

amplifies this

differential

it

to

a stream of

differential

logic-level pulses, one for every signal peak. These MFM -encoded pulses are sent decoding. The read chain

to

circuitry

3-20

chain

receives

the

head

transi-

output

differential

the

DDC for

includes

read read

as

peaks.

analog

an

3-98.

Line Receiver. The line receiver translates

the

differential

ST-506

Interface single-ended sition generator. The

MFM -encoded

WMFM+,

format

suitable for

output

write

WMFM-

input

of

the

data

lines

to

line receiver a positive-going pulse for every magnetic tion to be

3-99.

erator

the

tion

written

Transition

divides

logic level

of

current

on the disc.

Generator.

the

MFM frequency by two

of

the

output

through

The transition

determines

the

head. Each

the

transition

the

transi-

so

on

the

into

tran-

gen-

that

direc-

a

is

Theory of Operation

7942

and 7946

In MFM generates a transition on medium.

3-100.

source provides and supplies preamplifier/write source microprocessor and has two outputs, selected by Inner Track line. For tracks 0 to 511,

current

5 1 2 and above, the write

peres.

3-101.

operation, parameters of detector. microprocessor activates, via signal include driver/read write faults which can cause are listed in table 3-1 signal WFL T

Write

is

WFLT-L. Inputs to the write

current

Current

current

a write control

enabled by

output

Writ4~

is

Fault

the

microprocessor monitors certain key

the

If

an

abnormal condition

Unsafe signal

preamplifier

source and the head select logic. The

.-

L.

Source. The write

for

the

(WC)

driver

27.5 milliamperes and for tracks

operation via

IC's.

the

Write

current

Detector. During a write

the

US

IC,

WFLT-L

under

the

recording

current

read/write

signal to

The write

Gate

is

the

is

PLA, Write Fault

from

and lines from

to become active

the

description for

the

current

line from the

the

22.5

milliam-

write

detected, the

fault

detector

the

heads

read

the

write

fault

write

the

Power supply assembly A4 develops dc operating

voltages from the ac line voltage and distributes these voltages throughout the drive. The power

is

a self

poin ts a t

The

WI

to

power-on

output

host dependent

supply assembly also generates a signal.

Power supply assembly A4 switch -mode power supply mounted on a circuit assembly. Located in the assembly are all

the

of line cord connector, line fuse, line voltage selector switch, line voltages are + 5 V dc, + 1 2 V dc, and - 1 2 V power supply signal can be measured of are connected via cable assembly controller trollers PCA UO-A2 and PCA U 1-A2, disc drive assembly

The following paragraphs provide a more detailed description of Refer to figure distribution information.

ac line voltage components including

on/off

PCA-A4. See figure

not

adjustable. The power supply voltages are

PCA-A5, both device dependent

UO-A1, and tape drive assembly

switch, and line filter.

output

voltages and

attest

4-7.

the

power supply A4 circuitry.

4-

5 for detailed voltage and signal

reset

-contained printed

the

Output

dc.

The

reset

the

f ron t

voltages

con-

U1-A!.

3-102.

Disc drive assembly A 1 performs a self test tain functions include head loading and seeking to track tests, Ready are set true, allowing A 1 to respond to DOC mands via the operation of the disc drive, monitors spindle speed and either microprocessor shuts down operation via Land

3-103.

Note: Power supply assembly A4,

SELF TEST

of

key hardware functions

O.

Following successful completion

RDY-L

parameter exceeds predetermined limits, the

SKCM1P-L

and Seek Complete SKCMP-L

ST-

506 Interface. During normal

lines.

POWER SUPPLY

07942-60024, higher wattage supply assembly A4,

07940-60094, Tape Drive Service Manual. Power supply assembly A4,

07942-60024, following paragraphs.

used in

described in

is

at

power-on. These

the

off

-track

the

drive

unit

than

part

described in

of

com-

microprocessor

conditions. If

the

RDY-

A4

part

no.

is

a

power

no.

the

no.

the

cer-

the

3-104.

The ac line voltage assembly A4 through a printed (PCA) mounted -AC LINE connector. A mounted ac line of the ac line into operated by a through There lowing same inputs. A line filter following the fuse reduces level and power supply.

Also associated with VOLT AGE SELECTOR switch which selects line voltages of 115 Vac or is tion device protects if

AC INPUT CIRCUITS

is

connected

on/off

an

opening on

is

a fuse in

the

(SA,

250V) for both

of

line transients entering

the

amount

in

the

115 Vac position, a surge voltage

it

is

inadvertently connected to 230 Vac.

the

power switch. The fuse value

of switching noise leaving the

switch controls both sides

the

power supply. The switch

LINE-

the

pushbutton projecting

the

front

line side of

115-Vac

the

input

230 Vac. When

power supply from damage

to

power supply

circuit

panel of

the

ac

and

the

power supply

circuitry

assembly

PCA-

the

drive.

input

is

230-Vac

is

the

switch

protec-

is

fol-

the

a

3-21

Theory

7942

and

of

Operation

7946

3-105.

The

dc converter, converter. The the age regulated verted verter. Included thermistors current Vac

SWITCH MODE SUPPLY

switch mode supply consists basically

aback-boost

ac-dc

ac line voltage. This f il

is

supplied to

the

regulator,

converter

tered

back -boost regulator.

dc, approximately 150 Vdc,

to +

5,

+ 12,

and

-12

V dc by

in

the

ac-dc

that

limit

the

initial

to approximately 25 amperes

and

230

Vac.

and a dc-dc

rectifies

dc

operating

is

the

converter

power-on

peak

of

and

then

dc-dc

are

an

ac-

filters

volt-

The concon-

two

surge

at

115

3-106.

The switch mode supply nal for reaches 4.7

POWER

power-on

-ON

reset

RESET

and

PVAL-H.

at

least 100 milliseconds

At

power on,

5V

or higher. Signal

circuit

produces Power Valid

PVAL-H

after

goes to a high level. Signal PV low for

at

least 500 microseconds prior to going below 4.75V. Signal monitored supply nected to device dependent

at

a test

PCA-A4.

point

See figure

on

4-7.

controller

is

activated by

remains low

the

+5V

PV

AL-H

will also

PVAL-H

the

front

PVAL-H

PCA - A

the

sig-

output

then

go

the

+5V

can

be

of power

is

con-

2.

3-22

Table 3 -

1.

List of Mnemonics

Theory of Operation

7942 and 7946

MNEMONIC

ATN-L

CEO-L, CEI-L

CSAO-H CSA5-H

CSBO-H CSB7-H

thru

SIGNAL

Attention

Chip Enable, Bits

0,1

Con

trol/Sta

Address

o

thru

Control/Status Data thru

7

5

Bus,

Bits 0

tus

Bits

SOURCE

AS

-

Al

111

AS

-

AS/A2

81111

DESCRIPTION

HP

-

IB

managemen t in used to specify how bidirectional through

and which device must respond to

information. When ATN the

DIOI-H

carry

addresses or commands. When

TN

-L

A DI08-H

Enable driver IC disc drive assembly

DC -

IB registers in a selected DOC which comprise CSBO-H DOC

PCA-A2111

DC-IB bidirectional pass control and status the

HOC and a selected DOC.

put

to DOC PCA A2

W2.

Data

DI08-L

is

high,

lines

the

in

signals used to access

the

through

is

through

the

carry

read the

head -disc module of

Control/Status

CSB7-H.

terf

ace line

information

I/O

Bus

to

be

interpreted

-L

DI08-H

0101

- H

data.

preamplifier/write

AI.

Data

Output

via cable W2.

8-bit

bus used to

data

III

via cable

on

DIOI-L

the

is

low,

lines

through

the

Bus

to

between

Out-

CSRS-L

CSWS-L

trol/Sta

Con Read

Control/Status Write Strobe

tus

Strobe

AS

-

AS

-

IB

DC the trol/status through DOC-status medium information Read/Write through DATA 7 generates a trol/status DOC PCA - A 2

DC-IB signal used to pass control bytes from

Control/Status

through CSB7-H. A2111

signal used to pass bytes from

DOC to

the

HOC over

Data

CSB

7 -

H.

The bytes are of a

nature

Data

H.

SOO-nanosecond

bus read cycle.

III

the

HOC to the DOC over

Data

via cable W2.

Bus

since recording

Bus

The read strobe

via cable W

Output

CSBO-H

is

passed over

DA TAO-H

Output

Bus

CSBO-H

to DOC

Con-

con-

to

2.

3-23

Theory of Operation

7942

and 7946

Table

3-1.

List of Mnemonics (Continued)

MNEMONIC

DATAO-H thru

DATA7-H

DAV-L

DIOI-L DI08-L

DIR-L

thru

SIGNAL

Read/Write Data

Bus,

thru

7

Data

Valid

HP-IB Bus,

8

Direction

Data

Bits I

Bits 0

I/O

thru

SOURCE

AS/A2

~III

AS

m

AS

m

A2

III

DESCRIPTION

DC-IB bidirectional

read/write

pass HDC and a selected DDC or vice sa. PCA-AS

III

HPcate availability and validity of formation on through a receiving device able.

HP-IB bidirectional put data, commands, and between HDC. Transfer serial.

STDIR-L tion of Step signal active (high) DIR direction and when the from ly, "in" direction and heads move toward disc. Al

Connected between HDC

m and DDC

via cable W2.

IB

handshake line used to

DI08-L.

(I/O) bus used for

the

host computer and

S06 Interface control signal.

defines

the

read/write

STEP -L

read/write

the

center

an

active (low) DIR

Output

_ via cable W3.

8-bit

bus used to

data

between

PCA-A2

Data

I/O

Bus

DIOI-L

DAV

-L

indicates to

that

data

is a vail-

data

input/out-

the

transfer

other

is

bit parallel, byte

the

direction of

is

-L

defines

STEP-L

heads move away

of

the

disc. Converse-

the

to disc drive assembly

messages

heads when

pulsed.

-L

An

an

is

defines

read/write

center

pulsed,

of

the

ver-

indi-

in-

of

the

mo-

in-

"out"

an

the

DRIN-L/ DROUT-L

3-24

ta

Request

Da In/

Data

Request

Out

A2

III

tri

DC-IB used to Read/Write through tion HDC to programmed via Bus drive a given request line. HDC

-state

DATA

is

defined as being from

CSBO-H through CSB7-H to

PCA-AS

DMA request lines

transfer

Data

7-H.

the

DDC. A DDC

Control/Status

bytes over

Bus

The "out"

m via cable W2.

DATAO-H

direc-

the

is

Data

Output

to

Table

3-1.

List of Mnemonics (Continued)

Theory

of

7942 and 7946

Operation

MNEMONIC

DSO-L

DSIN-L/

DSOUT-L

DX,DY

EOI-L

GREEN-L

SIGNAL

Drive Select, bit

o

Data Strobe

Diff

eren

Data

End

Or

Green

In/

Out

tial

Identify

SOURCE

A2

III

AS

-

Al

III

AS

-

A2

III

DESCRIPTION

When active (low), connects

ST-506

disc drive assembly A 1 interface

cuitry.

A 1

DC-IB HDC-generated strobe lines which accomplish the transferring of data two DDC's over DATAO-H

Differential signal lines preamplifier/write

HP the used with signal A TN - L to perform a parallel polling sequence.

Dri

ve FAULT/ON to

the

Interface control lines to

Output

III

between

IB

control signal used to indicate

end of multiple byte transfers

for green LED in f ron t panel

front

to disc drive assembly

via cable W

the

through

LINE indicator.

panel via cable W

3.

the

HDC and one

Read/Write

DATA

driver IC's.

7-H.

to/from

Data

Output

4.

the

cir-

or

Bus

read

or

HSO-L, HSI-L, HS4-L,

HSI-H, HS2-H

IFC-L

INDX-L

HS8-L

Head Select, Bits

o

thru

8

Head Select, Bits

1,

2

In

terf

ace Clear

Index

A2

III

Al

III

AS

-

Al

III

ST-

506 Interface control signals.

of

0

to read

of

a track.

select-

head

is

selec-

in

the

a

as-

of

These lines provide a means ing each individual in a binary -coded fashion. When all four lines are inactive, head

Output

ted.

III

A 1

Head select bits preamp/write head select and control logic.

HP -

IB

general management line used to place known q uiescen t state.

ST-

506 Interface control line.

-L

INDX sembly A 1 once each revolution the

disc (16.67 milliseconds nominal)

to indicate

to disc drive assembly

via cable W

the

interface system

is

provided by disc drive

the

read/write

3.

input

driver IC's from

beginning

3-25

Theory

7942

and

of

Operation

7946

Table

3-1.

List of Mnemonics (Continued)

MNEMONIC

NDAC-L

NRFD-L

PES

PVAL-H

SIGNAL

Not

Data

Accep-

ted

Not

Ready

Data

Position

Signal

Power Valid

For

Error

SOURCE

AS

III

AS

III

Al

-

A4

III

DESCRIPTION

Normally,

and

the

ca tes

is

generated by a

in

the

PCA-A2

HP-IB cate devices.

HP-IB cate

ready

Bus

DIOI-H

Actuator

indicating

head

Indicates

puts Output cable

the

transition

the

start

spindle motor.

III

handshake line used

the

acceptance

handshake line used

that

all devices are,

to

accept

servo

amount

off

-track

that

are

up

to DOC

Wl.

signal

of

via cable W3.

through

displacement.

power supply

to

is

to

a low level

a track.

Hall-effect

Output

of

data

over

DI08-H.

control

and

their

PCA-A2

proper

a high level

indi-

The

signal

sensor

to DOC

to

indi-

data

by all

to

indi-

or

are

not,

Data

I/O

circuit

direction

A4

values.

III

signal

out-

via

of

RDY-L

Ready

Al

-

ST-

506

Interface

ROY

-L

becomes active (low) ing power within

speed,

recalibrated. PCA-A2

If

there

or

spindle speed control, ROY remain not

go

and

the

After

come active

During the

processor

ing

the

a speed

percent force

and

stop

cling is required to drive.

on

if: a) dc voltages

specification,

and

c)

III

via cable W2.

is a fault

inactive

low

until

head position

power on, ROY

within

operation

is

speed

of

variation

is

detected,

ROY

-L

high, lock

the

motor.

control

b)

head position

Output

in

the

(high). ROY

the

fault

is

-L

25

seconds.

of

the

continually

the

spindle motor.

of

greater

the

Power-on

restart

signal.

follow-

are

discs

are

at

is

to

DOC

dc voltages

-L

will

-L

will

is

cleared

recalibrated.

should

disc drive,

processor will

the

be-

monitor-

than

actuator,

recy-

the

disc

If

2

3-26

Table

3-1.

List

of

Mnemonics (Continued)

Theory

of

7942 and 7946

Operation

MNEMONIC

RED-L

REN-L

RMFM+, RMFM-

SEL-L

SIGNAL

Red

Remote Enable

MFM Read

Select

Data

SOURCE

A2

III

A5

m

Al

III

A5

m

DESCRIPTION

Dri

ve

for red LED in f ron t panel FAUL T to the

HP-IB control line used in tion with tween two programming data.

ST - 506 In

ferential signal which defines MFM transitions recovered by ing a prerecorded ted head. The transition of RMFM+ line going more positive than flux reversal on DDC

DC-IB DDC will respond to a given trol/status SEL-L

ION

LINE indicator.

front

panel via cable W

other

messages to select

alternate

terf

ace

the

RMFM - line represents a

peA

-A 2

signal used to select which

bus operation. When low,

selects DDC 0 (disc drive.)

data

track

the

III

sources

signal. A

track.

via cable W

with

Output

4.

conjunc-

of

a selec-

be-

device

dif-

the

read-

the

to

4.

con-

SKCMP-L

SRQ-L

STEP-L

TRKO-L

Complete

Seek

Service Request

Step

Track

0

Al

III

A5

m

A2

III

Al

III

ST-

506 Interface control signal.

SKCMP-L indicates

read/write final tion. Reading or writing should be

attempted

active (high). PCA -A 2

HP -

IB SRQ-L the

need for service and to request

interrupt

ST-

506 Interface control signal.

STEP-L causes to move defined by Direction signal DIR One Step pulse = one step = one track. Output

III

Indicates when the are positioned ermost PCA - A 2

heads have settled on

track

at

the

end

when SKCMP-L

Output

III

via cable W

general managemen t line.

is

used by a device to indicate

of

the

current

the

in

the

direction

to disc drive assembly A I

via cable

data

track).

III

W3.

at

cylinder 0 (the

via cable W

that

of

a seek

to DDC

3.

activity.

read/write

of

read/write

Output

to DDC

3.

the the

opera-

not

is

in-

an

heads

motion

L.

heads

out-

3-27

Theory

7942 and 7946

of

Operation

Table 3

-1.

List of Mnemonics (Continued)

MNEMONIC

us

VCMA, VCMB

WC

WFLT-L

SIGNAL

U nsaf e

Actuator

Coil Drive

W ri te

Write

Current

Fault

Voice

SOURCE

Al

III

lA

III

lA

III

At

III

DESCRIPTION

A read in which writing sence of write tions.

Drive Signal control circuit.

A line from sending head during a write. read

STWFL T - L warns ists in disc drive assembly A 1 which makes writing unsafe. PCA-A2 becomes acti ve for reasons.

preamplifier/write

current

is

enabled and

current

is

preamplifier/write

506 Interface control signal.

to

actuator

supplied by

the

write

current

III

to

that

via cable W3. Signal

driver line

flows whenever

there

is

an

ab-

or

data

transi-

voice coil.

actuator

current

the

Output

driver

a condition

Output

the

servo

source

read/write

to

the

IC's.

ex-

to DDC

following

WRITING:

• Open head.

• Shorted head.

• Improper write current.

•

An

off

-track

• Invalid or multiple heads are selected.

• Spindle speed

• A write

SKCMP-L

• Write gate

•

Attempting RDY

-L

• A write

drive

is

the

write protect option.

• Write

Disc drive assembly A cept fault processor.

current

further

has been detected by

condition occurs.

loss

when writing.

is

attempted

is

inactive (high).

but

to write

inactive (high). attempted

write protected

READING:

appears

commands

when

no write data.

with

when

1 will not

the

with

at

head.

after

the

disc

ac-

a write

micro-

3-28

Table

3-1.

List

of

Mnemonics (Continued)

Theory of Operation

7942 and 7946

MNEMONIC

WGATE-·L

WMFM+, WMFM-

SIGNAL

Write

MFM Data

Gate

Write

SOURCE

A2

m

A2

m

DESCRIPTION

If

the disc drive microprocessor will re -examine fault

and reactivate itself

dition clears.

ST-

506 Interface control signal. When WGA enables write the

disc. When inactive (high),

abIes

data

Output

III

via cable W

ST-506 ferential MFM signal which defines the

transitions to track. The transition line going more positive WMFM - line will cause a flux salon a track Gate

WGATE-L

disc drive assembly A

W3.

TE-L

to be read from

to disc drive assembly

Interface

is

data

to

3.

data

be

(provided

is

active).

deselected,

if

the

active (low),

be

written

it

the

signal. A

written

of

the

WMFM+

than

rever-

that

Output

I

III

via cable

the

con-

it

on

en-

disc.

Al

dif-

on a

the

Write

to

WS

Write Select

Al

III

Selects operation for the driver IC's When selected; when mode

the

WS

is

selected.

read or write mode

in

the

is

high,

WS

of

preamplifier/write

head -disc module.

the

write mode

is

low,

the

is

read

3-29/3-30

HOST

COMPUTER

DATA/CONTROL

INTERFACE

BUS

(DC-IB)

~

---------------I

HOST

DEPENDENT

CONTROLLER

I

(PCA-A5)

I H P - [ 8

....

1U1TE

..

" BU' ,

I I I

I

INTERFACE

I C

SELF

TEST

SWITCHES

&

DISPLAY

_______

~----------~--------------C-ON-TA"-O-l/~ST-A-TU-S-DA-T-A-aU-s------~,+_--+r_r~

~~~~I/

~~~~I

CONTROL/sa

TUS

ADDRESS

aus

L

_______________

J

~w~-~tSV

-

t2y

I

SUPPLY

~

tt2y

ASS

E M B L Y

POWER

ON

RESET

~~~)~tI2YP

FILE·PULL05A

IOEV

ICE

DmN

DEN

T

--l

I

CONTROLLER

I

(UNIT

1.

PCA-A2j

I

MICRO-

COMPUTER

ioEvICE------1

I

DEPENDENT

I

CONTROLLER

I

(UNIT

0,

PCA-A2j

I

~

I I

[N

I I

DIS

C

CONTROLLER

14----,.-.1

I C

CONTROL

I

___

J

FAULT/

ON

LINE

INDICATOR

DATA/CONTROL

INTERFACE

BUS

(DC-IB)

------------------------------,

I

DEPENDENT

CONTROLLER

A

51

I B I READ/WRITE

OATA

SUS

\e

/

FACE

r~-----------------------------------------------------------------~'/~--~~~

""

..

"n" .... "

'"

~L-

fit

/

$

i I

I~

I

RAM

I MICRO-

I~~

EPROM.~~O~ROM~D~_1_E~~1

PROCESSOR

rsELF

TESTli

SELF

TEST"ISELF

TEST

I

1

'

-f

,

I I 1

8

/

1

:LF

TEST

~y

DMA

GATE

I

ITCHES &

ARRAY

IISPLAY

IC

i

f--k

CONTROL/STATUS

ADDRESS

BUS

1/

DEVICE

DEPENDENT

Iffi----'

CONTROLLER

1

II

UN

IT

1.

PCA-A2)

I

MICRO-

I

CONTROL

I

COMPUTER

I

:

I

1

REAO/WRlTE

1

READ/IAITE

DA

TA

I

1

STA

TE

r

I

MACHINE

I I

~

____

.--J

~----l

TAPE

DRIVE

ASSEMBLY

I

(UNIT

1)

I

SERVO

TAP

E

I

1

(PC

A-A?)

~

DRIVE

MECHANISM

(Ai.

AB,

A9)

I

READ/

I

W RITE

I--

W RITE

I[PCA-A3)

I

HEADS

I

~----~

Theory

of

Operation

7942

and

7946

roEV

ICE ----

--I

~S~~

A~M~

------

--

----

--I

I

DEPENDENT

I I

(UNIT

0,

Ail

I

CONTROLLER

I

(UNIT

0,

PCA-A2)

I I

I

INE-R5rO,6cE

I i

~~ ~ -;E~O-=-O~;;-

~ ~ M-;L~

-

-1

1

H I I I

MFM

R/I

REA

D

H P L L 14--

__

~_--HI---

__

+--M-FM-R-I-W

_DA_TA______

R!

II

I

DATA

PRE

AMP!

1

IC

I

.m

I

II

,...-

CHD:NT:EL

i

DR

I'fIvREIRTErc

'S

I

_______________

J

--~t5V

~

+12V

I

CON:

: :

~

lEA I

·~~,J"EDR

H:::'

.m.""

I

~I

IC I I MrCRO-

Ii

I

PROCESSOR

-

&

I--

_

I

PLA

ACTUATOR

-

I

ACTUATOR

I I

(

HY

-12Y

POIER

ON

RESET

~~)~tI2YP

CONTROL

I

~

SERVO

I

::

I

CONTROL

I,

I

~

I I -

DATA

I

r-.---f----.!

I I

~"

SERVO

-",-

SERVO

HEAD

I

L.

J

DATA

SERVO

I

~~;:~LE

I

L

-~

--

----

I I

PREAMP

io----

FAULT/

ON

LINE

INDICATOR

I

SPINDLE :

IC

I

___

SPEED

I

SPINDLE

DRIVE

I I

I

CONTROL

1 I

I

L

______

--.l_

AIR

FILTRATION

COMP\JNENTS

Figure 3 -

3.

Disc/Tape Drive, Block Diagram

3-31/3-32

AC

I

INPUT

I

POWER

SUPPLY

HOST

COMPUTER

FlLEaFSMAX18A

A 4

I r

""'-"

RESET

--

••

+t2VP

L

__

~

I[)"EV

I-C-E-------

I

DEPENDENT

I

CONTROLLER

~

I

I PCA-A2 I

~S~E~~~R~E-R--------------------II

I I

IN\\-?FOA6CE

II

I

HU

DATA/CONTROL

r

I

PCA-A5

INTERFACE

r------

PLL

BUS

I

IC

I

M F M F

I

(D

C ~ I B I

~"--

__

--'

DAHl

H P - I B

READ/WRITE

DAH

BUS

B /

CDNTRDL/STATUS

DATA

BUS

I~/

,/

P

NNcNi\

~40

°gRW

E

RAM

MICRO-

~~bO~~~O~~~~EPI11J-,,-11

I

DISPLAY

IC

PROCESSOR

SELF

TEST

SELF

TEST

SELF

TEST

CONTROL

I

I 1

'-----r-----'

,

CO"

ROl

IS

TAT

~,

ADO

RE"

BUS

' :

~

/ !

..

---..-------'-I--H"'I----+I--i

____

L

_______________

J -

L_~---J

I

FAULT/

ON

LINE

INDICATOR

I

r--------,

I DEVICE I

I

DEPENDENT

I

CONTROLLER

I PCA-A2 I

--

---

-.

I

DATA!CONTROL

I

INTERFACE

BUS

I

PLL

I C

READ/MRITE

DATA

BUS

CONTROL/STATUS

DATA

BUS

AM

,/

I I I

MICRO-

~x~

EPRO~~~O~ROM

~_1_EPRO~

I

PROCESSOR

SELF

TEST

SELF

TEST

SELF

TEST

ttl'

/

CONTROL/STATUS

ADDRESS

BUS

1/

_________

J

IDC~IB)

I

DIS

C

CONTROLLER

Ie

i+--I--

__

-J

DlTI

I

I I

CONTROL

I

L

_____

J

FAULT!

ON

LINE

INDICATOR

Theory of Operation

7942

and

7946

~

-S

C-D

R-I-V-E

-A-1-

------

--

------

--

--I

I I

ST-506 I

INTERFACE

I--------------~

,

SEALED

HEAD-DISC

ASSEMBLY

I

~

I

I I I

I

I I I I

NFM

R/M

DATA

MICRO-

PROCESSOR

&

PLA

-

R

fW,

o

AT

A

CHANNEL

,

NFl!

R/M

READ

I

DAlA

PREAMP!

I,

WRITE

I

DRIVER

IC'S

,...--------,

ACTU~TOR

R/M

I

DRIVE

HEADS

DISCS

DATA

ACTUATOR

SERVO

CONTROL

SPINDLE

SPEED

CONTROL

:

~

I

:

ACTUATOR

~

I

'I

:

DA

TA

I

"

SERVO

HEAD

_,....-

DA

TA

I

I I

I

I I

S E R V 0

PREAMP

I C

SPINDLE

DRIVE

MOTOR

SPINDLE

I

I AIR

FILTRATION

I I I

L

____________

-1

______

C_O_M

P_O_N

_E

N_T

_S

___

-1..----1

Figure

3-4.

Disc Drive, Block Diagram

3-33/3-34

..

Theory of Operation

7942

and 7946

-------------------------------------------------------------------------------------------,

r

HOST

DEPENDENT

i

I

CONTROLLER

PCA-A5

I

(FRA5)

RUO/IAITE

I

DATA

8US

REAOIWRITE

DATA

BUS

DATAO-H

- OATAl-H 8

J2

35-3B

I 40-43

I

J3 010

I-l

HP-II

DATA

BUS

O!O2-l

2

')........-+-.------l

0103

-l

DIOC-l

ED 1-L DU-l

5/

NRF

O-l

NDAC-l

H P - I B

IFC-L

INTER-

10)

FA

C E

S

RQ

-L

llN-l

I C

II

0105-l

13

DI08-l

14

010

7-l

15

D108-l

16

A E

N-l

17

12.

SND

18-21

MICROPROCESSOR

DATA

BUS

-

MICROPROCESSOR

ADDRESS

BUS

DR

IM-l

OS

IN-l

DAOUT-L

o

SOU

T-l

CONTROl/STATUS

DATA

BUS

45

!IiII."!-_C_S

B_O_-

H_-

_C_SB_l_-_H

-++--7/

H=

n

CSR

S-l

13

CSWS-l

PYAL-H-~

CONTROL/STATUS

rP

'

3,5.7.

,

O.

12. I

,

19.24.

i 29, 34

, ,

,

ADDRESS

BUS

18

17

.~._~_Si~-!~

__

~~5~.H

------+-11:;

.2:;

SEL-L

'22

t5Y

..

J~>

r

I

-----------------------------------

______________________________________________________________

J

r--------------------------------------------------------1

I I

I~~

I

~~

(J:

WI

P I

112YP

4,8.8/

SWITCH-

t5Y

5,7.9"

3A

~

ODE

t

12Y

13

250 Y

NONTUE

SUPPLY

-

12Y

DEll

Y

15 10

12

POWER

SUPPLY

ASSEMBLY

A4

( F R A 4 )

5

BIPI

j

I

..J

FlLE=FSJEF01B

NI

FAN

B I

112YP

~

G N D

12P I

/

'\. /

5.

:

/

WIP2

/ :

DA

H/CONTROL

INTERFACE

BUS

(OC-IB)

12

DC-II

I

II

DC

POIER

1

1A

Figure

3-5.

Disc Drive, Functional

Block Diagram, (Sheet 1 of

3)

3-35/3-36

DITA/CONTROl INTERfACE

BUS

(DC-IBI

[D---,

12

I

II

DC

PDIER

fIlE

of

S

lAX

161

12P2

1 1

I I I

1

I

!

I

20

I

1

I I

i

I I

1 1

"

i I

I

~------------------------------------------~

, DEVICE

DEPENDENT

\

CONTROLLER

PCA-A2 (FRA2)

101HZ

'\

~

CLOCK

1

151HZ

GEN

r-

J2

~----~

J4

CSRS-l

/

13

"

I

/

I

eSIS-l

14

"

1

I

CDNTROl/STITUS

1

IDDRESS

BUS

SEl-l

I

-

HDA

SWITCH

_ DESCRIPTION

U4B4

PROM

I

CSBO-H

-

25-29

/ 1 CSB1-H

L

..

.....

TRANS-

...

"

I.

;;-aJ

1-

~

CEIVER

...

---

CDNT

ROll

STA

lUS

1 1

0111

8US

(

1

SND

I

'!,

CONTROLLER

1 C

&

REGISTER

DECODE

LOG

I C

10-12

,.

PHASE

LOCKED

LOOP

RUI'

Rlfl<

"

1/

11

RIFI-

I C

DIS C

CONTROLLER

Ie

SKCMP-l

t--

TRKO-L

t--

WFll-l

I---

I NOX-l

W RITE

I

RRIFI-

I"

1/

!If

1-

I

r

.....

:~

(

I

2.4.P

~1~:h~h~1

1

~

19.20

PRE-

COMPENSATION

~

J3

H59-l

"

1/

I

HSI-l

"

1/

HS1-l

I,

1/

I

Ii

14

16

5T-506

INlERfACE

"I3P2

/ 1

I

"

1

I

1

I

~

"

13PI

1

" 1

I

1

I

IS

I

Theory

of

Operation

7942

and

7946

13

3

0111

IS

4

CONTROL

I

15.

19.2

4.

I

DOC

'---I

PUPO

ERRORS

1-

REGISTER REGISTER

I---

H50

- L

I'

I

I I

1 1

I

1 1 1

"

1

I I

1

I I I

1 1

I

1 1 1 1

IIP3

I

19.34,

S9,

H,

0,50

01110

-H

-

lOOP

liCK

SElEC T

~

J

~

R~ER

..

I

..

---.

35-38

/DllIl-H

lL.....

j

....................

..

40

-

43

45

" 9 r

....

-

I •

___

,,~DRIVER

~

1

I~

1 DI5C

1 1 1 1

DAIN-l

REIO/IRIlf DIH

8U5

/ I

,

1

OHA

~-r-----------+l

HAN

0-

/

1

DSIN-l

, 1

SHAKE

(,-...L---_-------I

CON

T R 0 L

1

OROUT-l

/ 1

"

1

/

1

DSDUl-l

"

JI

0-.

51

~'11Y

I

(: • PlAl-H

POIEA

DN

RESET,

All

CIRCUITS,

I

GND

I'S~

L

______________

_

1

..

,.

LA

lC

H

~

RDI-l

I---

SlEP-L

r----

DIA-l

r----

Hllf-

L

r----

H51-l

---

HS4-l

-----

H51-l

---

HSO-l

-----

D50-l

--

I

1/

5K

CMP-ll,

1

I

1

~

I

1

10

12

1/

I

TRKO-ll"-

(

Wf

LT-l

.s..

1/

I

/

I

20

1

INDl-~"

1/

"-

I

/

22

RD I -l

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1/

1

5lfP-l

I

"

,

I

/

I

14

1/

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1

26

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I"

1/

I

/ I

34

DIA-L k

1/

I

1

HI

TE-l,,,

? I

I

SND

I

r::DD

I

PINS, lHAU

3

RE

D-l

J5

-"

GREEN-l

I,

1/

I

'51

-l-l;?

8~",,,

__

J

lIUlT/DN-ll

ME]

II

De

POIER

1B

Figure 3 -

5.

Disc Drive,

Functional

Block Diagram, (Sheet 2

of

3)

3-37/3-38

FROM

18

I

""

S T-5 0 6

INTERFACE

H2

H2P2

Theory

of

Operation

7942

and

7946

~--------------------------------------------------------------------------------,

I

DISC

DRIVE

ASSEMBLY

A1

:

I I

L

J1

RMFMI

ACTUATOR

SERVO

CONTROL

IJ

18

'.L:

RMFM-

nSmS

DATA

'TRICK

0

'.L:

UFN-

POMER

ON

RESET

SEEK

SERYO'

14

'.L:

UFM'

INDEX

ODD

IN

SERYO-

13

"

IT

SPEED

PICK

ACTUATOR

~

DE~OD-

CONTROL

WRITE

CHAIN

576

KHZ

CLOCK

..

ULATOR

READ

CHAIN

I 3

I-----..,...-..,+--~-<.

1.4.6.~

'----++--"'---<11.

I

O. I I.

" I

II~i~510

V

COUNT

NOT

REIDY

COUNTER

RESET

HAl

IE

GI

TE

1

W3P2

L 4

CON

T R 0 L

I'----+-+--+_-<

VI

DC

POHR

VIP~

10 20

18

t4

16 14

11

12

ST-506

CONTROL

51

GN

IlS

f I

UL

T

RICKO

Off

TRICK

ON

PEAK

/JI

DIR-L '

__ -..

I DIRECTION

IN

M 1 C R

0-

~)---':

---v

G-I-T

-E

--L----+I

I N

PUT

I--V-R-l-TE-G-AT-E--+-------~

PRO

C E S S 0 R

~,,----7-----------.j

BUFFERS

OR

I IE S E l

EC

T

•

/

TRKO-L

OUTPUT

~(--'-i

---I

"_O_X

-_l

___

---i

~R

I

VE

R S

/:

HS8-L

)

: HS4-L

..

):

HS1-L INPUT

f-)------H

s-o

--L

---.j

B U F

FER

S

(

GHO

~

ILL 000 P [NS.

I T

HRU

33

WG

ITE-L

-

050-L

IN

PUT

~T-

__

s

T_E_P

-_L

__

~

B U F

FER

S

DRIVE

SELECT

•

SK C MP-L

;:

VflT-l

OUTPUT

~-------I

DR

I V E R S

):

ADI-L

..

J3

TRICK

0

INDEX

HEAD

SEL

ECT

8IT S

PDiE R

ON

RE

SET

FIULT

VAITE

GATE

DRIVE

SElECT

STEP

SEEK

COMPLETE

HRllE

FIULT

AEADY

P L A

NORMIL

REGULATION

S

TOP

MOT

DR

[NN

ER

TRICK

SERYO

ENIBLE

E

lEN

IN

SEEK

I

H

ODE SELECT SW

IT

C H

000

IN

INVERTER

SEEK

~

S

LOP

E

It-

__

---.tr----'---,

EVEN

IN

-'

SERY

0

ENABLE

MOTOR CURRENT

~-------------+~ISELECTOR

I

TACHO-

HCURRENT

l 000

[N

VEL

DC

IT

1

COMM

AND

8

IVELOCITY

I YElOCITY

METER

r

~

________________

~

INVERTER

I

DAC

I

EAAOA

VELOCITY

COMMAND

8

AT

SP E EO

SEEk

COMPlETE

WAITE

GATE

,9

ES

ON

I

PEAK

o

ET

I

'------'

PES

Off

T

RACK DE

T

I I

ON

PEAK

Off

TRACK

SEEK

CDMPL

EIE

HILL

SENSORS-

1311

3-PHISE

OAIVE

14-

___

5

_P

E_E_O

__

---'1'--_"_0

R_M_I_L

_R_E_G

U_L_A_T

I_O_N--I S PIN D L E

I

'5Y

-

POWER

'12Y

-

ON

-lOY _

RESET

STOP

MOTOA

S

PEED

350

HZ

CLOCK

_

CONTROL

'121

_

L-

____

--J

SPINDLE

SPEED

CONTROL

5 T

OP

MOT

0 R

I I

SPINDLE

MOTOR BRA

K E

R E

LAY

R E

LA

Y

DRIVER

HAlL

SENSOR-

INDEI

POMER

ON

AESET

~--------~~--------------~SPINDLE

92.1

KHZ

CLOCK

-

SPEED

I'--

__

C_O_U_H

T_E_R_R_E_S_E1

__

~

C H E C K E R

IT

SP

E E 0

COUN T NOT

REID

1

r--W_M_F

_M

'---t~J

LIN

E

,--W_MF_N_-

--+!]

R E C E I V E R

I

READ/WRITE

D A T A

CHANNEL

HRITE

GATE

I

NNE

A T A I

CK

POWEA

ON

RESET

flU

LT

HEAD

SE L ECT

W RITE

CURRENT

SOURCE

W RITE

fA

U L T

DETECTOR

i

BITS

HEAD

HSO-L

THAU

HS31

S E L E C T

t

r-_H_A

[_T_E_G_I_T_E

_~

C D N T R 0 L

LOG

I C

YCMA

YCHS

SERYO'

TRANSITIONj

GEN

OX

DY

NA

lIE

GITE

UPLlFJER!

SIGNAL

CONDITIONER

DIFF

RMFM'

LINE

~.

D RIVE R

r---------

ic--------------

i

I

SEALED

HEAD-DISC

ASSEMBLY

I

J

ox

:

01

I

we

I

us

READ

PREAMP/

W RITE

DRIVER

I C • S

m-L

'"

L [ 1

H S I -

H'N SH S 1-

H.

I I

r-------1----~

I

A I W

HEADS

I

!

t

====:t==~~8~=====lFF====~D~IS~C~

ACTUATOR

5

i

VO

ICE

COIL

4

SERYO

HEAD

SERVO

0 SPINDLE

r-

______

s_EA_,_o-

______

...J.I_---I

PRE

AMP

~

MOT

0 A

~~

9 216

MHZ

3-PHASE

,-----,

~,

15Y B I

Ie

~

II

L..!.....-,

'12V

.

NORMAl

RE6ULATION

I DRIIE J HAlL-EFFECT I

~

-

1152

KHZ

3-PHASE

DRIVE

2.3

~

CLOCK

STOP

MOTOA

ACTUATOR

~--~~-------~--~~~---------~~-----~

SENSORS-1311

"

.!,

GEN

91.1

KHZ

LOCK

I I

AND

INOEl

I

I 576

KHZ

PICK

L '

ACTUITOR

~m;;;;;mm(~

....

~ I

II

~

DRIVER

\.

LOCK

SOLENOID

-y~IR

fIlTRIT~-.J

l

__________________________________________________

~~

__________

~~~---------------------------------------~~~~-~~~_~~

_____

J

FILE=FSIEFB7D

1C

Figure

3-5.

Disc Drive,

Functional

Block Diagram, (Sheet 3

of

3)

3-39/3-40

SERVICE INFORMA TION

4-1.

INTF~ODUCTION

WARNING

The

disc/tape

tain

operator

prevent

service activities

personnel.

electrical shock,

drive does

serviceable parts. To

to

not

con-

refer

all

service-trained

WARNING

All products which utilize head

deaner Material Follow when

• The field replaceable assemblies

all

Ulsing

(FRA's) in

static; sensitive devices. Take propriate precautions when removing drive. and wrist strap components are contained in

anti

-'static work station, 93001-0749.) Immediately removal, store

static, conductive plastic bags.

are

Safety

I

Use

Data

applicable

the

tape

CAUTION

the

drive are

the

FRA's f rom

of

an

is

the

shipped with a

Sheet

precautions

head cleaner.

I

anti

-static

required. (These

FRA's in

tape

(MSDS).

electro-

ap-

the

pad

part

no.

after

anti-

Do not cycle the -LINE switch on

• off

and

• Do not connect or disconnect

HP-IB cable(s) from w hen da

This section contains information useful for troubleshooting includes field replaceable assembly (FRA) locations, parts location details, and cabling connections. This information replaces similar information in the

Tape Drive Service Manual. Following isola-

tion of trouble to

drive by the

reference should

section or service manual for applicable

troubleshooting information.

the

for section. If component from

removal and replacement information.

4-2.

The following tools and materials are required to service the disc drive:

• Torx* T 10 Driver

• Torx*

• Torx* T25 Driver

drive power supply are also provided in this

SERVICE

TIS

unnecessarily.

the

system

ta

on

the

HP -

lB.

the

drive. Information provided

either internal

then

it

is

necessary to remove

the

be made to

drive, refer to section V for

TOOLS

Driver

the

is

transferring

disc drive

self

-test the

Output

the

drive

or

the tape

diagnostics,

appropriate

specifications

an

FRA

or

• The drive be handled with care. Also,

drive kilograms/34.8 pounds) size would indicate.

• Do not

off

or ferring Packard Interface

*TORX

is

a registered

is

delicate and should

is

turn

when the system

data

hea vier ( 1

the

-LINE

on

the

Bus

trademark

than

switch on

is

trans-

Hewlett-

(HP-IB).

of

the

•

Nut

Driver,

the

5.8 its

Camcar Division of Textron, Inc.

• Pozi Driver,

• Antistatic Work Station,

9/32

No.1

11

part

no.

9300-0794

4-1

Service

7942

4-

The (FRA's) identified by shown in figure

removal tion formation.

Note:

Inf

orma

tion

and

7946

3.

FRA

locations of

VI

for

The

within U 1 in figure refer Manual, Section Parts.

• U

• U 1-FRA

LOCA

4-4.

and

replacement

FRA

following FRA's

FRA 1 are

to

I-FRA3

the

iden

tape

4-4.

the

7 (servo assembly)

TIONS

field replaceable assemblies

the

self

-test

diagnostics

Refer

tif

Tape Drive Service

(read/write

to section V

instructions

ica tion

drive assembly

not

For

VI,

and

contained

shown in

their

location,

Replaceable

assembly)

for

and

to

ordering

detail

are

FRA

sec-

in-

4-6.

Details of ac

tion are shown in figure

4-7.

In

applied to its destination in one of two states:

tive or inactive. The signal

age level (high or low) makes

which ly identified by a signal mnemonic. Refer to table 3-1. logic signal mnemonic

signal

mnemonics indica te analog,

POWER DISTRIBUTION

input

wiring

SIGNAL

the

disc drive logic circuits, a digital signal

the

signal was designed. This action

A mnemonic

with

an

without

NOTATION

with

an

active high voltage level. Signal

an

data

and

dc power

3-4

and

in figure

is

active when its

the

action occur for

an

"-L" suffix indicates a

active low voltage level. A

"-H"

suffix indicates a logic

"-L"

or

"-H"

suffix usually

bus, or

control

bus signals.

distribu-

4-11.

ac-

volt-

is

usual-

is

• U

I-FRA8

•

UI-FRA9

tachometer)

4-4.

An

is for as detailed in figure

Manual, ly

from of

nections to power supply assembly

figure

Also, extra

nected in parallel

ments for described in

4-5.

Cable connections between drive signals via these cables The mnemonics appearing in figure defined in table

CABLE

overall cabling

provided

the

WI.

power supply assembly

the

DC-IB

connector, allowing

in

cable assemblies shown in figure

with

the

Details of how cable

drive

are

4-

5.

cable assembly W2 in

the

SIGNAL DISTRIBUTION

are

shown in figure 4 - 11. The

(head stepper motor)

(capstan motor

CONNECTIONS

diagram

figure

4-11

exception

shown in figure

to

both

connectors on W2

Tape Drive Service Manual.

3-1.

of

the

disc/tape

4-11.

The pin assignments

and

Tape

Drive

of

power cable

WI

supplies voltages

A4

to

the

4-

5.

A4

the

DC-IB

is

signals to be

DDC's. The pin assign-

the

FRA's in

distribution

shown

in

and

drive

4-11

Service

assemb-

components

Cable

con-

are

shown in

drive has

con-

remain

the

disc

figure

4-12.

4-12

are

an

as

of

are

4-8.

Block diagram of are figures the diagram large bold of table references, for example: figure 3 - 5

troller

FRA2

Each of these diagrams in section III panied by a

4-9.

A

supply assembly

purposes.

shown in figure 4

the

be noted removal drive.

Note: Power supply assembly A4,

BLOCK DIAGRAM

the

disc/tape

provided

three

the

page. These numerals

FRA5

III,

in

section III of this manual.

3-3

and

3-4.) To

sheets of disc drive

(figure 3-5)

numeral

are

m,

and

circuit

each sheet

in

the

diagrams for host dependent

device dependent controller

disc drive assembly

description.

POWER SUPPLY

number

voltages

of test points

A4

The

locations of these test points

-7.

monitored

that

access

of

the

front

Refer

to

section V for removal details.

07942-60024,

higher

wattage

for

Also provided

to

used in

drive

facilitate

functional

is

identified by a

lower

right-hand

are

boxed in

m.

A4

are

provided in power

troubleshooting

at

the

test points.

the

test points requires

panel assembly

part

the

drive

unit

than

and

are

power

disc drive

(See

references to

block

corner

text

and

Included

FRA

is

details of

It

from

no.

is

a

con-

1

III·

accom-

and

should

in

test

are

the the

4-2

Service Information

7942 and 7946

supply assembly A4,

07940-60094, Tape Drive Service Manual. test point information given in figure ply assembly A4,

07942-60024,

4-1

o.

Host dependent controller PCA - A 5 requires one

executive (EXEC) EPROM, two disc EPROM's, and

two tape used in

be

must pins

at

locations of

4-11.

The drive can execute self which are programmed into

host dependent controller and both device den t con trolle:rs. When

these routines are automatically initiated to form a series of subtests which first verifies operation

then

the completion of the host dependent controller tion of portions are

form many hardware checks first by microdiagnos-

tics and as

seeks, reads, and writes.

4-7

HC~C

EPROM's to

the

in place on the two

W3 on PCA-AS.

PCA-AS

drive. Also, a circuit board jumper

the

EPROM's and

SELF

of

the

disc and tape drives. Upon successful

the

sellf

test,

run

simultaneously. The subtests

then

by higher level macrodiagnostics such

described in

for servicing power

in the drive.

be

in

See

TEST

-test

the

host dependent controller, and

the

disc drive and tape drive

part

place when PCA-AS

IIDISK

figure

W3.

diagnostic routines

the

drive

no.

the

Use

the

sup-

no.

AND TAPE

4-8

for the

firmware of

depen-

is

powered on,

per-

por-

per-

is

the

4-12.

The disc/tape drive self

following:

Tape drive Tape drive Disc drive

indicator

DISPLAY RESULTS switch

2-digit

SELF TEST switch

See figure

II

regarding

provided in information regarding self

-test

manuals for

4-13.

The tape drive FAULT indicator

which illuminates when a

tape drive or

Drive Service Manual,

for a complete list of

luminate

Note: The tape drive

SELF-TEST

FAULT indicator BUSY

indicator

FAULT/ON

self-test

the

results,

TAPE

the

may be illuminated when

2-digit is passed self test. This condition cates during the tape load sequence.

display

4-1

and figure 4-2.

use

of

the

following paragraphs. For detailed

refer

the

disc drive and the tape drive.

DRIVE

the

tape cartridge.

FAULT indicator.

rear

indicating

that

a drive

CONTROLS

-test

controls consist

LINE

these controls and indicators

the

interpretation

to

the

individual service

FAULT

Section

the

panel self

tha t the

INDICATOR

is

a red display

fault

is

detected in

Refer

III,

Troubleshooting,

conditions

FAULT indicator

-test

display

dri

ve has

indi-

fault

has occurred

of

the

(f ron t panel) (f ron t panel)

(f ron t panel)

(rear panel) (rear panel)

(rear panel)

Information

of

to

the

Tape

that

will

the

is

the

il-

Go/no-go cated by the dicators and are indicated by indicator. failures are presented on the self the

rear

-test

self command. The itiated the

drive or by

itiate Diagnostic command. Details of

tic tests are provided in the individual service

manuals for the disc drive and

test results for the tape drive are

front

panel FAULT and

go/no-go

See

figure

panel. The host can determine details of

failures using

internal

at

any time by controls on

test results for

the

front

panel

4-1.

the

CS/80

diagnostics can also be

the

host computer using

indi-

BUSY

the

FAULT/ON

Details of subtest

-test

display on

Request Status

the

rear

the

tape drive.

in-

disc drive

LINE

in-

panel of

the

In-

diagnos-

4-14.

TAPE

The tape drive green color during self test or host ini nostics' when loading and unloading a tape cartridge, and when engaged in reading, writing, and searching. The tape drive self test takes

7 seconds to complete without a tape cartridge stalled, approximately 1 cartridge installed, and approximately 2 minutes with a

DRIVE

600-foot

BUSY INDICATOR

BUSY

indicator illuminates with a

minute

cartridge installed.

with

tia

ted

diag-

about

in-

a 1 SO-foot

4-3

Service

7942

4-15.

The

red/

status

plied LINE (green) portions of for ing. Next, time

self

seconds to complete. test, disc drive fails self test, solid red that test routines

Inf

orma

tion

and

7946

DISC

DRIVE

DICATOR

disc drive

FAULT/ON

LINE

green display which signals the

of

the

disc drive. When line voltage

to

the

disc drive,

1 second to

that

-test

routines. Self test takes between 6

the

display will change to a solid green.

a self

verify

the

green portion will flash

the

disc drive

with

a flashing green display

-test

failure

are

the

FAULT

the

display will

that

the

display

is

executing its

If

the

disc drive passes self

the

display will change to a

has occurred,

still accomplishing some

indicator

(red)

but

IIhousekeepingll tasks. When these tasks plete'

the

green

indicator

ing

that

the

drive mands such as diagnostics. flash again

when

the

will extinguish,

is

ready to accept host

The

green

indicator

disc tape drive respond to these commands. A solid red display indicates

(unit

2)

has failed self test.

that

the

host dependent

IN-

operating

is

and

illuminate

is

function-

during

internal

and

If

indicating

the

are

com-

indicat-

com-

attempts

and

green

controller

is

ap-

ON

the

12

the

self-

will

to

8.8.

readout display are functioning. The display will blank

until

-test

a

self the

display will immediately

displayed)

to indicate

self test

that

is

completed. In

command issued by

and

remain

blank

all segments of

the

system to

go

blank

until

(8.8

self test

the

then

go

case of a

unit

0,

is

not

is

com-

pleted.

the

When f rom display ready to start. When

SELF TEST switch

the

host

is

requested.

is

blanked to indicate

the test commands are issued to first

tests

is

one

that

causes pear. The display completed.

If

is

release

then

is

not denied) display will appear. This message will tinue

to be displayed

is

released,

which

pass/fail

until

time

result.

the

When self test has been completed on the

drive (host dependent controller, disc drive, tape drive, a

P .X. (pass)

X.

is

the

drive HP -

and

power supply),

or

an

IB

F .X. (fail) result. The

device address.

is

pressed, release

If

release

switch

the

blanked

granted,

the

is

gran

that

the

is

released,

drive. One of

8.8.

display

until

an r .d.

SELF TEST switch

display will show

the

display will show

ted,

self test

self-

to

ap-

self test

(release

con-

units

numeral

the

is

the

is

the

of

After

a successful self test, a solid green display

dica tes

green display indicates

4-16.

The SELF TEST switch pushbutton nal self

recessed behind

by

The

the nostic command. Both to tain not

current

4-17.

The self

7 results routines. Whenever self test operation voltage

that

the

SELF

TEST

disc drive

SWITCH

that

is

idle

the

disc drive

and

is a momentary

switch which initiates

-test

diagnostic routines. The switch

the

rear

panel and

the

tip

of a ball point pen or similar object.

self

-test

routines

same as those

initiated

of

the

power-on

self

-test

host dependent controller

by a host-issued

these routines

routines except

the

can

by the switch

(unit

executed as these subtests would destroy

run

-time

environment.

SELF-TEST

-segment of

is

-test hexadecimal display which reports the

of

applied,

DISPLAY

.display consists of a 2

internal

the

SELF TEST switch

self

the

display will

-test is

initiated,

and

a flashing

is

drive

be

activated

are

that

2)

subtests

diagnostic

either

or

when

first

active.

contact

inter-

diag-

similar

cer-

-digit

show

in-

is

are

are the

the

by

line

an

Note:

decimal points in

are

tied directly to

dent

controller

the

signal

presence of this voltage.

+5

the

host

Vdc supply and

The

The decimal points should illuminated self test the

drive.

4-18.

DISPLAY RESULTS SWITCH

at

all times during both

and

normal operation of

The DISPLAY RESULTS switch contact results to be displayed on switch TEST switch. When switch The switch must release the released. pressed, the is

pushbutton

is

operated in a similar

is

pressed, a request

is

granted

display will

If

an r .d.

switch

is

restored to

switch which causes self test

the

self

manner

the

DISPLA Y RESULTS

for

release

be

release

pressed or denied. go

blank

is

denied

and

If

until

when

message will be displayed. When

released,

the

display.

depen-

remain

is a momentary

-test

display.

to

the

SELF

is

generated.

held down

release

the

pass/fail

is

granted

switch

until

result

The

is is

4-4

Service

7942

Inf

orma

and

tion

7946

Note: In

Following rele:ase, pressing

times will display one test information. The normal sequence play However, failure here will be reported first, any

Note: A

The

in

be, (FRA) failed,

indicated by the display U.x., where

identifies

A.x.,

test failed number.

multiple failing FRA's. Multiple FRA's are listed in

descending order unit the

of

unit

troller (unit

(unit

the

event

of

a self

-test

the

drive will have requested release to update the the

drive

is

not

this update operation

some time to complete.

the

period)

switch will be inactive. This means

that switch may have longer or tion has been completed.

the

other

self

fail ure. When it monitoring

switch. The only

drive tion test results. The drive will respond to host computer. The red FAULT/ON be illuminated from by powering down the drive.

information

order,

where

has no failures

unit

1)

the DISPLA Y RESUL

than

pressed

test results for units

since

results reporting.

unit

2 (host dependent controller)

-test

will

can

is

to

the loop can only be achieved

unit

and

the

unit. The failing FRA

numeral

is

indicated by a

It

is

numher.

and

FRA numbers. Host dependent

2),

subtest numbers, together

DISPLAY RESUL

normal

after

of

unit

2 (the HDC)

failure

unit

enter

into

the

DISPLAY RESULTS

perform

toggle

any

commands

LINE indicators will

at

displayed for each failed

failed, field replaceable assembly

subtest failed.

x.

possible for a failing

of

most probable failure.

to

Refer

disc drive (unit

error

operating correctly,

may

During

to

be pressed for a

period

the

update

the

two specific sequences

is

a special type

2 fails self test,

an

function

under

out

the

this time. Exit

identifies

report,

to

figure 4-2 for a listing

of

switch a

0,

1,

and

is

and

infinite

that

this

unit 2 self-

from

and

The

the

2-digit

it

will display only

0), with a brief

failure,

logs.

If

take

this

TS

time

opera-

number

is

to

dis-

2 in order.

tested first, a

will

inhibit

of

loop

the

condi-

not

the

green

unit

failing

is

FRA. A

unit

and

unit

numeral

indicated by

sub-

hexadecimal

to have

con-

tape drive

of of

will

x.

If

de-

is

scription service manuals.

Note: The sequence mode described above

4-19.

The disc drive routines circuits. The self at check overall operation of the disc drive. The disc drive must pass all host dependent controller (unit

2)

subtests to come on line. In dependent controller (DDC) subtest failure, drive run drive assembly A 1 continually operations faults Details in for a summary

4-20.

The disc drive routines which dependent controller controller servo system firmware. When drive automatically subtests which verify operation The subtests by microdiagnostics macrodiagnostics such

a

Go/no-go FAULT/ON the presented on The host using internal

of

the

sub tests,

is

distinct When sequencing test results, the

results must be displayed

the

DISPLAY RESULTS switch before on the the or

the

-line

(return

last result has been displayed,

display will

F

.x.

(fail).

INTERNAL

internal

and

run

-test

power-on,

is

time

are

the

following paragraphs.

consist

allowed to come on line.

error

and

of

the

disc drive.

logged

of

these two diagnostic tools

of

the

SELF

can

are

is

powered on, these routines

initiated

perform

test results are indicated by

LINE indicator on

disc drive

the

and

the

self

can

determine

CS/80

diagnostics

are

from

the

device will go back

from release).

return

DIAGNOSTICS

diagnostics include self

time

error

routines, normally

of

a series

fault

reporting circuits in disc

in

the

diagnostics.

TEST

execute self

programmed

and

to

many and

as

seeks, reads,

details of subtest failures

-test

display

details of self

Request Status command.

can

also be

listed

in

pass/fail

to P

.x.

and

fault

of

subtests which

the

event

After

monitor

Run

-time

disc drive

Refer

-test into

device

perform

of

the

hardware

then

by

the

on

the

initiated

the

respective

mode.

all

of

with

After

(pass)

reporting

activated

of

a device

the

power-on,

certain

errors

error

are

provided

to

table 4-5

diagnostic

the

dependent

the

a series

disc drive.

checks first

higher

and

writes.

front

panel

rear

-test

failures

at

-test

disc

and

logs.

host

disc

are

of

level

the

of

are

panel.

The

any

4-5

Service

7942

time

or

Information

and

7946

by controls on

by

the

host

the

rear

computer

panel

using

of

the

disc drive

the

Initiate

Diagnostic command. Details of the diagnostic

the

tests are provided in

4-21.

SELF-TEST

The subtests

into

six

the

tests

are

performed, paragraphs. listing of

detected by

The

first group

4-1)

checks

run

functional

in

each group, listed

Refer

the

subtests

the

tests.

of

the

subtests include a short checkout

microprocessor, a checksum of

EPROM

write/read

of

the timer IC.

A full set test initiated host,

limited

the

and

DMA gate

circuitry,

is

initiated

by

then

only the

RAM test

existing

the

test

of

and

of

these sub tests

at

either

run

-time

described above check

and

circuits,

interfaces resident

The second group

4-

2)

table

checks functions independent of disc drive assembly These subtests include tests

IC's and circuits, a checksum

PROM,

and

the

following paragraphs.

SUBTESTS

during self test can be divided

groups. A general description

in

the

order

that

is

provided in

to tables

and

subtests (01

operation

the

of

the

following

4-1

and 4-2 for a

failure conditions

through

the

both

07, table

HDC. The

of

the

of

they

HDC

EXEC

DDC EPROM, exhaustive

all of the RAM, a loopback test

array

IC,

a test of

a verification

the

HP-

IB

interface

is

run

only

when

of

the

self

power-on. When self test

the

SELF TEST switch

timer

test,

the

are

performed. This

DMA test,

is

to

protect

or

and

the

environment. The subtests

the

of

the

operation

in

subtests

(OAH

operation of disc drive

the

through

of

HDC.

the

IC's,

12H,

AI.

of

the

DDC resident

of

the

device specific

sensing

of

the

proper 12 volt

is

power.

The

third

group

4-

table

2) assembly A 1 to disc drive performed and

monitored for proper completion, direction,

and

pulse count.

The

fourth

table

4-

and

2) drive assembly A 1 servo mechanism, function, command

as

verifies

of

subtests (13H

checks

is

the

operation of disc drive

the

extent

selected, a restore

of

through

servo activity. The

command

a few seek commands

group

performs

of

subtests

further

(lDH

checks

through

and

far

as position sensing. A scan ID

that

the

sector headers

of

are

the

1 CH,

issued

2SH,

disc

read

can

is

be

read. A more exhaustive sequence of seeks executed, both verifying

as

well

The table 4-2) and outer

monitoring the speed performance.

fifth

group of subtests (26H

checks seek, read,

two sectors,

diameter

at

(OD).

the

subsequent location as

through

and

write,

inner

diameter

Reads

and

writes

(ID)

is

both

and

are

then

SEH,

one

the

also

performed on every surface.

of

The sixth group

4-

2)

checks

circuitry.

Circuit scan ID command, aborted, un

correctable errors.

and

tests (SFH

out

the

error

tests include: ID not found on a

underrun

both ECC correctable

Note: An additional test

successful initialize

through

and

fault

6SH, table

detection

condition, a command

and

is

run

after

a

and

read

(subtest 26). This test uses subtests

66H attempts factory-recorded from

product

through 6 SH.

to read

the

disc

and

number

The test

the

product

match

number

it

with

the

resident in the HDA description PROM located in the

DDC.

a

4-22.

SELF-TEST

There are

-test

self

means

three

results to

of

the indicator. The second way display on means of

the

the following paragraphs provide details three

methods

4-23. and

FAULT/ON

green LED's which comprise

FAULT/ON

of

status

momentary

the

solid red flashing green display occurs when the disc drive powered on

display remains a solid red

that

the host dependent controller (unit f ailed self test. display indicates

and

is

test indica tes When a self

ready for operation. A solid red display

tha

t the disc drive has failed self test.

-test

ERROR

ways which

the

front

rear

CS/80

Request Status command. The

are

used to

LINE

panel. The

REPORTING

the

disc drive reports

user. The first way

panel

FAULT/ON

is

via

third

report

self

INDICATOR.

LINE indicator signal

disc drive. See figure

and

green display and

and

self test

At

the

that

failure

the

is

executing.

and

green, this means

end

of

self test, a solid green

disc drive has passed self

is

indica ted, the 2

the

of

-test

the

is

LINE

self

-test

way

is

how these

results.

The

front

panel

operating

4-1.

then

If

2)

-digi

by

red

A

a

is

the

has

t

4-6

Service

Inf

7942 and 7946

orma tion

hexadecimal self

-test

display should be consulted

to determine the source of the failure.

4-24.

2-digit 4-2)

SELF-TEST

hexadecimal self-test display

DISPLAY. The

rear

(see

will normally show a pass (P.X.) or fail

panel

figure

(F.x.)

indication, with X. denoting HP-IB address 0 through is all of the results for time, displayed. assigned, and

7.

When

used to toggle

until

all of the information has been

Unit 0

the

SELF TEST RESULTS switch

out

results,

unit

is

the disc drive,

unit

2

is

0,

the

display will show

1,

and

2,

one

unit 1 is

the

host dependent

unit

at

not

a

controller.

Note: The

"Unit

2"

terminology for

the host dependent controller applies only to

disc drive self

-test

the

display. The host operating system

as

addresses the controller The "Unit

2"

designation for

host dependent controller

the

self

because

-test

unit 1 S.

the

is

used

display does not have enough digits to present a U

15

readout.

(Refer tables

4-2.

to 4-1,

)

(Refer tables

4-2.

to 4-1,

)

The following are examples of typical display readout sequences:

• SELF TEST PASS

DISPLAY MESSAGE

P

.3.

Indicates

that

unit

0 (disc drive) and

unit (host dependent controller) have passed self test. The

•

SELF-TEST

HP-IB address

FAILURE

is

set to 3 .

- UNIT 0

(DISC

DRIVE)

DISPLAY

F.

3.

Indicates

(disc drive) or controller). The Press and release

that

MESSAGE

self test has failed on uni t 0

unit

HP-IB address

2 (host dependent

is

the

DISPLAY RESULTS

set to

3.

switch.

2

Depending on the subtest failed,

than

indicate more

one failed FRA. In

the

display may

the

case of

multiple FRA failures, the assemblies will be reported in order of most probable failure. Details of

the subtest failed follows the FRA failure

is

information. The following

2-digit

U.

A.

P. = Self

F.

0.-6.

readout display.

FIRST DIGIT

Unit

=

number

designator

Field Replaceable

Ass'y

designator

Self

number

test

=

Failing self-test

subtl~st

numb digit.

I~

r,

pass

fail

hi

Unit

(See

Field Replaceable Ass'y

(See

HP-IB

O.-F.

g h

a summary

SECOND

number

figure

number

figure

address

Failing self-test subtest number, low

digit.

DIGIT

(0-2)

4-1)

(1-6)

4-1)

of

(0-7)

(0

-7)

the

U.O.

Indicates

that

unit

0 (disc drive)

report its results upon subsequent operation of

the

DISPLAY RESULTS switch. has passed self test and has no results to report, will change that

unit

2 [host dependent controller] will be

next operation

the

display to U.2. to indicate

of

then

the

displaying its results next.) Press and release DISPLA Y RESULTS switch.

A.4. Indicates

A4)

A.2. Indicates

controller

probable cause

that

FRA4

is

the most probable cause

that

PCA-A2)

(power supply assembly

FRA2 (device dependent

is

of

the failure. Push

of

the

second most

release DISPLAY RESULTS switch.

1.1. Indicates

defined in table 4-2 (bit 0 of DDC self Press

U.2. Indicates

that

subtest

11

has failed. This

as

"12V

-test

register) not set".

threshold

and release DISPLAY RESULTS switch.

that

unit

2 (host dependent controller), will display its results next. and release DISPLAY RESULTS switch.

F.3. Indicates

that

unit

2 has no results to report

is

ready to

(If

the

unit

switch

failure.

and

bit

Press

0

is

4-7

Service

7942

•

Inf

and

7946

and

the

SELF-TEST

DEPENDENT

orma

tion

self

-test

FAILURE

CONTROLLER

readout

cycle

-

UNIT

is

complete.

2 (HOST

S

= FRAS (HDC

6 = Connectors

• P2 - Identifies

the

PCA-AS)

DISPLAY

F.3. Indicates

(disc drive) or controller). The Press

and

that

release

MESSAGE

self test has failed on

unit

2 (host

HP-IB

address

the

DISPLA Y RESULTS

switch.

U.2. Indicates

that

unit

2 (host controller) has failed self test. Press release DISPLAY RESULTS switch.

A.S. Indicates

controller the

failure. Push

RESULTS

0.3.

Indicates defined kilobytes of RAM

that

PCA-AS)

switch.

that

in

table

FRAS (host

is

the

and

release DISPLAY

subtest 03 has failed. This

4-1

as

ll

failed

• Press

DISPLA Y RESULTS switch.

F.3. Indicates

that

self

-test

complete.

4-25.

Diagnostic drive of A Request Status issued to get back QST AT of executed, a defined in

Manual,

executed

24) will be set referred bytes When specific self

•

REQUEST

command

and

an

1,

this means

1.

When

20-byte

the

part

and

it

to

as

returned

bit

24

is

-test

PI

- Identifies .the most suspect FRA:

1 =

FRA

2 =

FRA2

4 =

FRA4

STATUS.

(DIAG)

is

execution message

that

a self

-test

command

CS/80

the

field

Instruction

(REQST A

reason

Request Status

is

returned. This field

no. S 9 S S - 3442. When self test

fails,

the

Diagnostic Result Bit (bit

in

the

Fault

Error

the

from

set,

Error

PI,

Fault

the

Request Status command.

P2, P3, P7,

results, as detailed below:

1 (disc drive assembly A 1)

(DDC

PCA-A2)

(power supply assembly A4)

error

unit

dependent

is

set to

dependent

probable cause

IITest

readout

issued

returns

If

of

last 1 S

and

release

cycle IS

an

Initiate

to

the

a QSTAT

has occurred.

T)

should be

for

the

Set

Programming

Field (sometimes

Field)

and

of

P8

the

contain

3.

and

of

is

disc

is is

is

20

Same code as

0

• P 3 - Failed disc drive (unit Refer

to table 4-2.

• P7 - Failed disc drive

4-

3,

table

Disc Drive

• P8 - Details of failed disc drive

Note:

See figure

The

information from dri

ve, depending on

In

order

source for a

necessary to note

in

P 3 (failed self P7 (disc drive point in figure number P7 intersect identified of these codes, information iden

4-3,

P8 Signal Source.

detailed

given in P8

various sources in

to

identify

particular

the

-test

error

4-2 where

(vertical column)

number

(horizontal column)

is

the

by a

letter

together

supplied by

tif

ied sources,

PI

0)

self

-test

error

condition.

Error

Condition List.

error

condition

is

obtained

the

test error.

the

reporting

fault,

numbers

given

subtest) and

condition). The

the

and

reporting

source,

code. A listing

with

is

provided

subtest.

Refer

condition.

disc

it

is

P 3

the

the the

to

below.

DE -

Data

Error

Byte

Recoverable

0

LSB

Marginal

1

2

3

MSB

4

Note: More

example, if one location received

uncorrectable

Marginal Uncorrectable Uncorrectable

than

one bit may be set. For

(ECC)

error

on

and

write

an

other locations all had recoverable errors, the

data

error

byte will be set to

09H.

E - Disc

Controller

IC

Error

Register

4-8

Service

Inf

7942 and 7946

orma tion

Data

0

LSB

Track 0 error

1

Aborted

2

ready

Unused

3

=

4

10

not

Unused

5

CRC e rro

6

=

Bad

MSB

7

FC -

Fault

Code List

Refer to table

N - Number of seeks

Specifies

the

block

4-4,

number

address

or

found

Fault

mark not

command -Drive

write

r

fault

found

Code List.

of

seeks performed before

not

fail ure occurred.

S - Disc Controller

LSB

0

=

1 2

=

3

4

=

5

=

6

= =.

7

MSB

Z - All zero's. This

IC Status Register

Error Command Unused DRQ Seek

Write

Drive Busy

bit.

in

(data

complete

fault ready

is

a valid subtest

progress.

request)

(normally

set)

number/error

condition pairing. However, no additional

is

information

given in P8.

"Unit fault". Using P3 and P7 to identify

signal source shows "FC"

that

table

indicates 4-4

lists AEH

ve

is

dri

4-27.

on

the

RUN

4-4

as

"Verify position operation reveals

wrong head"

TIME ERROR AND

as

should

as

the source. This

be

consulted. Table

the fa ul t.

the

P8

F AUL T REPORTING

The

return

of a nonself

that

a full status should be requested. A Request

Status command should thus be issued to get back

the

reason for

hardware

occurred,

be set in

the

of

command. P7 will contain the disc drive

and in information.

•

P7

• P8 -

of a QSTAT of 1 following

-test

command to the disc drive implies

the

QSTAT of

fault

or

data

error

the

Diagnostic Result Bit (bit 24) will

the

Error

Fault

Field (Fault

20 bytes

certain

- Disc

If

controller paragraph

If

P7 controller paragraph

fault

P7

is

returned

from the Request Status

cases, P 8 contains additional

code. Refer to table

is

in

the

range of

IC

error

4-25

for details.

in

the

range

Ie

status register

4-25

for details.

the

1.

Assuming

of some kind has

Error

4-4.

50-6F,

register

of

70-

(E).

8F, P 8 (S).

issuance

that

Field)

fault

code

P8

is

disc

Refer to

is

disc

Refer to

not

a

4-26.

REQUEST STATUS EXAMPLE. The following example shows how to P3, P7,

and P8

command following a self

Pl= P2= P3=

returned

1

2 26H

for a Request Status

-test

failure.

P7 = 3DH P8 = AEH

P I and P2 indicate FRA 1

(disc:

drive assembly A suspect FRA indicates This

that

is

defined in table

to read one sector

the

seek or error

read failed

condition

that

the most suspect FRA

I)

is

FRA2 (DOC PCA-A2). P3

the failed self

at

the

".

is

3DH, defined

-test

4-2

as "While

outer

diameter,

P7 indicates

interpret

PI,

P2,

is

and the next most

subtest

is

26H.

attempting

that

in

table 4-3

either

the

disc

as

4-28.

The

which links

service-trained person. The

Exerciser

describes how devices and includes specific

EXTERNAL EXERCISER

CS/80

external exerciser

the

disc drive internal diagnostics to a

Reference Manual,

the

exerciser interfaces to

is

CS/80

part

information

an

interpreter

no.

5955-3462,

External

CS/80

for

the HP 794X Disc Drives. The following paragraphs briefly describe

functions

of

the

external

the

exerciser commands.

4-29.

AMIGO

The

AMCLEAR command clears

channel which

CLEAR

is

currently

(AMCLEAR)

the

addressed.

device on the

4-9

Service 7942 and 7946

4-30.

The CANCEL command causes graceful termination them

4-31.

The write

Information

CANCEL TRANSACTION (CANCEL)

of most

in

the

reporting phase.

TEST

HP-IB

CHANNEL

loopback test over

CS/80

CHANNEL

command

the

transactions, leaving

(CHANNEL)

initiates

HP-IB

a read

channel.

and

2 DMA Test. Performs

power-on.

3

Timer

power-on.

If

the value range correspond to

Test. Performs

command

is

the

is

directed to

also 0

following tests:

through

the

DMA test

the

timer

test

unit

0,

3.

These values

the

run

valid

at

4-32. (CICLEAR)

The connected to

4-33.

The data log.

4-34.

The within the

4-35. (DIAG)

The which reside in firmware. parameter an diagnostic test number. This directed to

If

value range parameter to

o =

CHANNEL

CICLEAR command will

the

CLEAR

error

DESCRIBE

DESCRIBE command allows

the

HP 85.

PERFORM

DIAG

integer

the

command

the

following tests:

Full

following

LOGS (CLEAR LOGS)

LOGS command- clears

log,

the

currently

command

The

bytes.

loop count. The

unit

15

for

is 0 through

Run

three

INDEPENDENT

channel.

error

rate

SELECTED

addressed

INTERNAL

invokes diagnostic routines

the

internal

DIAG

The

(HOC) or

is

directed the

Time Self Test.

HOC tests as well as

command

first two

diagnostic test

3.

These values correspond

o self test.

clear

any

test log,

UNIT

unit

DIAGNOSTICS

device

of

these bytes

third

command

unit

0 (disc drive).

to

unit

Performs

CLEAR

command

the

run

-time

and

the

fault

(DESCRIBE)

information

to be sent to

controller

has

three

are

byte

is

a

may

be

IS,

the

valid

number

the

unit

o =

Unit

include power-on

Random

performed

=

Full

2

from (ID)

3 =

one-track again.

4-36.

OUTPUT

LOG)

The

ER T LOG

rate

test log

errors

read or

write-then errors using

4-37.

The exerciser

4-38.

The fault have a

are

the

EXIT

OUTPUT

FAULT

log,

occurred

CLEAR

0 DOC

Stroke Seek Test. A

outer

are

Incremental

CLEAR

program

an

LOGS

power-on

the

HOC self test; however,

DOC self test

Seek Test. A

per loop.

diameter

performed

seeks

ERROR

command

which

-read

accumulated

PROGRAM

command

FAULT

LOG

accumulation

on

command

per loop.

Seek. Performs successive

from

contains

were found

error

LOGS command.

causes

to exit.

command

the

disc drive since

self test. This does

is

performed.

total

of

256 seeks

total

of

(00)

to

inner

00

to

10

RATE

allows access

rate

until

(EXIT)

LOG

TEST

an

accumulation during a read-only

test.

Error

the

log

the

CS/80

(FAULT

allows access to

of

the

faults

the

was issued.

the

entire

256 seeks

diameter

and

LOG

(ERT

to

the

error

of

rate

is

cleared

external

LOG)

which

last time

not

are

back

all

test

the

= HOC

4-10

RAM test on allocated

system

is

Test. Performs

an

empty

to

the

units

not

tested.

lk

and/or

the

data

two

pass RAM buffer. the

operating

RAM

4-39.

OUTP'OT

HELP

INFORMATION (HELP)

4-45.

SPARE (SPARE)

Service

7942

Information

and

7946

The HELP command prints all of names.

4-40.

INITIALIZE

The INIT MEDIA

routine on has a valid value of correspond to

B

= Initializes

P = Initializes the logic region

= Initializes

I

4-41.

The PRESET command ca uses all recen t

information disc maintenance tracks.

4-42.

the

tracks, sector headers, and logs

dealloca ted. Factory spares unchanged.

the tracks, The spare table (factory and field spares) written

and

back onto

UPDATE DEVICE LOGS (PRESET)

in controller RAM to be logged on

REQUEST STATUS (REQSTAT)

MEDIA (INIT MEDIA)

utility

disc drive. The INIT MEDIA

the

following;

the

entire

maintenance tracks are cleared.

performs

B,

P,

and

logic region. Spare table, spare

drive. Logical tracks, spare

the

maintenance tracks.

the

an

initialization

I.

These values

are

left

and

field spares are

and

command

utility

intact.

logs are

is

the

The SPARE an address which

4-46.

OUTPUT

SP

The information in

4-47.

OUTPUT DEVICE

The

TABLES command accesses internally the

operational status of

4-48.

PERFORM

The

SERVO test checks system. An exha usti ve sequence of seeks verifying monitoring sequence of seeks

4-49.

SET UNIT NUMBER (UNIT)

The UNIT number

is

drive

4-50.

PERFORM

RATE

utility

ARE TABLE command accesses

within

the

utility

to be addressed

unit

O.

TEST (WTR

physically relocates a

is

reserved for sparing.

SPARE

the

subsequent location as well as

speed performance. The

is

allows

TABLE

spare table.

TABLE

device

the

SERVO TEST (SERVO)

the

repeated six times.

the

within

WRITE-THEN-READ

ERT)

(SPARE TABLE)

(TABLES)

the

tables stored

in

order to determine

device.

operation

user

to

select

the

device.

of

the

is

executed

track

to

the

servo

entire

the

unit

The

disc

ERROR

The REQSTAT the

device to

4-43.

TEST (RO

The RO ERT command allows a sequential or random read to read errors.

4-44.

The log which contains errors which were found during Run-time

log

PERFORM

OUTPUT RUN LOG (RUN LOG)

RUN

is

cleared using

utility

the

ER

T)

LOG command allows access to

data

sends a status message from

exerciser.

READ-ONLY

take

place in order to locate any

an

accumulation of all read

errors are accumulated

the

CLEAR LOGS command.

ERROR

run

RATE

the

until

run

time.

the

The WTR ER T command writes a predefined pattern all

4-51.

When troubleshooting to do intermittent. same self self test the may

In identify certainty. In listed the self

over a specified

data

which was written.

area

of

the

disc,

TROUBLESHOOTING

the

disc drive,

is

to determine

A repeatable

-test

fail result

is

performed.

other

hand, occurs

not

always cause a self

the

case of a repeatable fault, self test will

the

failing

the

as

the

possible cause of

FRA's, one

-test

display.

at

event

a time,

if

the

fault

to

be presented each

An

intermittent

at

random intervals,

-test

FRA

that

in

with

more

the

is repeatable

usually causes

failure.

a 95 percent

that

one FRA

the

failure, replace

order given

then

first

fault, on

data

reads

thing

the

time

and

in

the

or

is

4-11

Service

7942

Information

and

7946

Note: Cable faults (an open cable

conductor, loose cable connector, etc.) may present a multiple

FRA failure message. The FRA's listed will be the

defective cable. All cabling

should

therefore

replacing

Note: Cables W 1

long to allow

assembly

circuit

adjacent cabinet. This allows a FRA

1 to be connected

Attempt

running

circuit from

self test following

without

the

cabinet.

to isolate

FRA's

any

and

AI)

the

at

either

be checked before

FRA's.

W 3

are

sufficiently

FRA

1 (disc drive

to be connected

to

the

disc drive

substitute

into

removing

fault

to a specific

the

replacement

end of

into

the

FRA

the

FRA.

1

FRA

of

by

each

4-52.

DISC DRIVE

MAINTENANCE

No regularly scheduled preventive required for

4-53.

the

disc drive.

TAPE

DRIVE

maintenance

MAINTENANCE

The tape head requires cleaning intervals. The head must be cleaned each week after

using a new tape Also, head cleaning three

to five back

the

of important data instructions Manual, Section

600-foot

errors

that

the

are

encountered. Tape head cleaning

are

I,

cartridge

is

recommended

-up

operations requiring

tape cartridge. Above all,

tape head be cleaned

given in

General

the

Tape Drive Service

Information.

for

at

the

first time.

after

any

regular

the

IS

and

every

use

it

is

time

t::::::I

I

FILE=PAILL01A

Figure

~

4-1.

L---

----

....

'"

VON

F

'-

\.

I

RED

GREEN

Front

Panel

BUSY INDICATOR

FAULT INDICATOR

FA

ULTI

LINE

IN

DICATOR

Self-Test

GREEN

-(iN

RED

-ON

RED

ON

OFF

ON

Display

GREEN

ON

FLASHING

ON

FLASHI

NG

OFF

'-4ESSAGE

EXECUTING SELF

TEST

TAPE

DRIVE

TAPE

DRIVE

TAPE

CARTRIDGE

FAILED

SELF

IN

DICATOR

1

SECOND

SELF

TEST

(U2l

FAILED

EXECUTING SELF

TEST

DISC

DRIVE

DISC

DRIVE

SELF

TEST

DISC

DRIVE

DISC

DRIVE

SELF

TEST,TEST

ROUTIN

ES

DISC

DRIVE

SELF

TEST;READY

FOR

DIAGNOSTICS

TAPE

OR

ACTIVE

OR

TEST

FOR

AFTER

OR

CONTROLLER

SELF DISC

DRIVE

OR

ACTIVE PASSED

OR

ACTIVE

FAILED

STI

LL

ACTIVE

FAILED

DRIVE

INITIATING TEST

4-12

Service

7942

Inf

orma

and

tion

7946

DISPLAY RESULTS SWI

TCH

DISPLAY

8.8 P. -

F

.•

r.d.

U.2.

U.O. U.1.

SELF TEST

SWI

TCH

c.D

MESSAGE

DISPLAY SELF SELF RELEASE

HOST

CONTROLLER

DISC

TAPE

TEST

PASS

TEST

FAIL

DENIED

DEPENDENT

DRIVE DRIVE

GO/NO-GO

--HP-IB

]

UNIT

]

TEST

ADDRESS

FAILED

RESULT

A.1.

DISC

DRIVE

A.2.

DEVICE

CONTROLLER

A .

4.

POWER

A.5.

HOST

CONTROLLER

A.6.CONNECTORS

0.0.

6.8

8.S

S794:2A01

DEPENDENT

SUPPLY

DEPENDENT

DISC

DRIVE

SUBTEST

TABLE

SEE AND

4-3

ASSE~BLY

SELF-TEST

FA I LED

4-1,4-2

FOR

CONDITIONS

DISC FRA

DRIVE

FAILED

A.O.

A.1.

A.2.

A.3. A.4.

A.5. A.7.

A.S. A.9.

0.0.

.

8.8.

NOT

DISCERNABLE.

ASSEMBLY

IT

TESTED

DRIVE (INCLUDES

MOTOR

STEPPER

DEVICE

CONTROLLER READ/WRITE

DIRTY

HOST

CONTROLLER

SERVO HEAD

CAPSTAN

(INCLUDES TAPE

SELF-TEST

SUBTEST

REFER SERVICE

PART

FOR

FAILED

AS

UECHANIS~

CAPSTAN

AND

HEAD

MOTOR

DEPENDENT

HEAD

DEPENDENT

ASSEMBLY

STEPPER

MOTOR

TACHOMETER)

DRIVE

FAILED

TO

TAPE

MANUAL

NO.

09144-90030

DETAILS

AN

AND

GOOD

ASSEMBLY

MOTOR

DR I VE

TAPE FRA

DRIVE

FAILED

Figure 4-2.

Rear

Panel Self

-Test

Display

4-13

Service

7942

and

Information

7946

Table

4-1.

Host

Dependent

Controller

(Unit

2)

Self

-Test

Subtest

List

READOUT (HEX)

88

01

02

03

04

05

06

07

GROUP

Microprocessor failed.

Test

Checksum

Test

DMA

HDC

HP-IB

Configuration

1

of

the

of

last 15

machine

timer

interface

first 1 kilobyte

of

EXEC

circuitry

EPROM

kilobyte

test

failed.

test

failure -cannot

of

not

within

failed.

of

RAM

failed.

RAM

find a valid

SUBTEST

failed.

specification.

unit

O.

4-14

Table

4-

2.

Disc Drive (Unit

0)

Self

-Test

Subtest List

Service

7942

Inf

orma

and

tion

7946

READOUT

(HEX)

OA

OB

OC

OD

OE

OF

10

11

12

GROUP

pUPa

Value

DMA

Write

register).

Write

register).

Device specific

12 volt threshold

Value

2

register

read

loopback test failed

to

to 23 head select line did

read

written

from

3

2

head select line did

PROM read

from

pUPa

bit

(bit 0

a disc

and

was

OFH

register was

transfer

into

of

DDC

controller

SUBTEST

when

read

back.

not

value

written.

into

DMA RAM.

out

of

DMA RAM.

not

set

head

bit

3 (bit 1 of

not

clear head

RAM - subsequent checksum failed.

self

-test

IC register

bit

register)

not

value

3 (bit 1 of

not

written.

DDC

set.

self

-test

self-test

13

14

15

16

17

18

19

lA

IB

lC

GROUP

Timeout

Restore

Seek completed, seek complete

but

Seek status

Seek

Seek completed,

Seek completed, not

Seek completed,

3

occurred

Command

is

set

in

command

or

the

command

indicate

after

drive selected while

issued

and

bit 3 of

self

it.

DDC self

completed, Seek complete

-test

register.

failed, disc

but

pulse

the

direction

controller

count

direction

failed.

bit

-test

was

bit

waiting

is

not

set

in

register.

not

IC status register indicates reason.

IC

error

register indicates reason.

not

I,

as expected.

not

15

as expected.

(bit 2

of

did

not

indicate

set

the

in

for

drive

disc

controller

either

DDC self

out.

ready

disc

-test

controller

status.

IC status,

IC

register) did

4-15

Service

7942

and

Inf

orma

7946

tion

Table 4-2.

Disc

Drive

(Unit

0)

Self

-Test

Subtest List (Continued)

READOUT

(HEX)

10

IE

IF

20

21

22

23

24

25

SUBTEST

GROUP 4

Scan ID failed due to

Scan ID failed, reason indicated

Scan ID failed, reason indicated in disc

A seek failed in

A seek failed in status.

A seek failed

A Scan

not

Was

in

10

failed in

10

in

the

able to complete all

time.

data

error.

in

disc

the

seek test, command did not complete.

the

seek test, command completed -

the

seek test, command completed in failure.

the

seek test.

seek test indicates

the

that

seeks in

controller

the

drive

the

IC status register.

IC

error

register.

but

no seek complete

is

on

the

wrong track.

seek test

within

the

allotted

26

27

28

29

2A

2B

2C

20

GROUPS

While the

While or

While failed, or

While of

While read failed,

After unique or

While of

While read

attempting

read failed.

attempting a write

the

write

attempting a write

the

attempting a write

the

wri

attempting a write

a successful

pattern

data

different

attempting a write

the

wri

attempting a write

failed,

te

or

te

or

to read one sector

failed.

data

read

did

failed.

the

data

read did

write

for

each surface), test produced a seek failure, a read failure,

from

that

failed.

the

data

read did

at

the

outer

diameter,

then

read of one sector

then

read of one sector

not

match

then

read of one sector on surface

and

then

that

written.

read of one sector

not

match

that

read of one sector on every surface (with a

at

written.

the

on

either

00,

either

00,

either

0,

either

surface

written.

then

read of one sector on surface

and

then

read of one sector

not

match

that

written.

on

1,

either

surface

the

0,

either

1,

either

seek or

the

seek

the

read

the

seek

the

seek

the

4-16

Table 4-2.

Disc Drive (Unit

0)

Self -Test Subtest List (Continued)

Service

Information

7942 and 7946

READOUT

(HEX)

2E

2F

30

31

32

33

34

After unique or

While or

While

a successful write

data

pattern

different

for each surface), test produced a seek failure, a read failure,

attempting

the

write failed.

attempting

read failed, or the

After unique or

While or

While read failed, or

After

unique

or

a successful write

data

pattern diff

for each surface), test produced a seek failure, a read failure,

eren t from

attempting

the

wri te failed.

attempting

the

a successful write

data

pattern different

for each surface), test produced a seek failure, a read failure,

then

from

that

a write

then

a write and

data

read did

then

that

a write

then

a write and

data

read did not

then

from

that

SUBTEST

read of one sector on every surface (with a

written.

read of one sector on surface

then

read of one sector on surface

not

match

that

written.

2,

either

2,

either

read of one sector on every surface (with a

written.

read of one sector on surface

then

read of one sector on surface

match

that

written.

3,

either

3,

either

read of one sector on every surface (with a

written.

the

seek

the

seek

the

35

36

37

38

39

3A

3B

3C

While

or

While

attempting

the

wri te failed.

attempting

read failed, or

After unique or

While

or

While read failed,

After unique or

While or

While

a successful write

pattern

data

different

attempting

the

wri te failed.

attempting

or

a successful write

pattern

data

different

attempting

the

wri te failed.

attempting

read failed, or

a write

a write and

the

data

then

read of one sector on surface

then

read did not

then

read of one sector on every surface (with a

read

match

of

one sector on surface

that

written.

4,

either

4,

either

the

seek

for each surface), test produced a seek failure, a read failure,

from

that

written.

a write

a write and

the

data

then

read did

then

read

of

one sector on surface

then

read of one sector on surface

not

match

that

written.

5,

either

5,

either

the

seek

read of one sector on every surface (with a

for each surface), test produced a seek failure, a read failure,

from

that

written.

a write

a write and

the

data

then

read did

read of one sector on surface

then

read of one sector on surface

not

match

that

written.

6,

either

6,

either

the

seek

the

4-17

Service

7942

and

Inf

or

rna

7946

tion

Table 4-2.

Disc

Drive

(Unit

0)

Self

-Test

Subtest List (Continued)

READOUT

(HEX)

3D

thru

3E

56

57

55

58

59

SA

5B

After unique or

Reserved

While failed.

While or

While failed,

While seek

While the

While failed,

a successful

pattern

data

different

attempting

attempting a write

the

write

attempting a write

or

attempting

or

the

attempting a write

wri

te failed.

attempting a write or

for

the

read

the

for

from

future

failed.

data

failed.

data

write each

use.

to

read

to

read

SUBTEST

then

read

of

one sector on

surface), test produced a seek failure, a read failure,

that

written.

two

did

read

did

sectors

then

read

then

read

not

match

one sector

then

read

then

not

match

read

at

the

of

two

of

two

that

at

the

of

one sector

of

one sector

that

OD,

sectors

written.

inner

written.

either

at

the

at

the

diameter

at

the

at

the

every

the

OD,

ID,

surface

seek

either

(lD),

either

or

the

either

the

(with a

read

seek

read

seek

read

the

or

5C

5D

5E

SF

60

61

62

63

64

While failed.

While or

While failed,

attempting

attempting a write

the

write

failed.

attempting a write

or

the

data

GROUP 6

A

read

command

found

A

condition was

The aborted

ECC

error

was

read

was

performed

not

drive was deselected

status

correctable

uncorrectable

to

read

was issued

not

detected.

was

not

test,

read

two

then

did

not

detected.

with

and

detected.

write

full

read

operation

write

sectors

read

of

read

of

match

for a non

the

a seek

full

that

DMA

command

operation

failed

operation

at

the

two

sectors

two

sectors

written.

-existent

disabled.

failed.

or

the

failed.

ID,

either.

sector.

issued.

data

the

seek

at

the

ID,

either

at

the

ID,

either

The

expected ID

The

expected

The

expected

was miscorrected.

or

the

overrun

command

read

seek

read

not

in

4-18

Table 4-2.

Disc Drive (Unit

0)

Self -Test Subtest List (Continued)

Service

7942

Inf

orma tion

and 7946

READOUT

(HEX)

65

66

67

68

SUBTEST

ECC uncorrectable test, read operation failed or value read indicated correction was attempted.

Product number, cannot

be

read.

Product number, value read was unitialized.

Product number, wrong number.

that

4-19

Service

7942

and

Information

7946

Table 4-3.

Disc

Drive

Error

Condition

List

READOUT

30

31

32

33

34

35

36

37

38

39

3A

(HEX)

Miscompare.

Failed.

Passed second scan ID

Data

errors

Seek

timeout

Seek

timeout -Command

Seek -

Seek

fault.

R/W

Command

write

drive

data

occurred

- disc

fault.

not

ready.

byte

count

aborted.

ERROR

on

different

on

every

controller

completed

invalid.

CONDITION

head.

location.

IC has

not

- seek

completed

complete

command.

bit

not

set.

~

3B

3C

3D

3E

3F

Disc

controller

Disc

controller

Unit

Fault

Verify

fault.

occurred,

position

IC

timeout

IC

timeout -cannot

but

unable

- reset.

to

failure.

reset.

identify

condition.

4-20

P7

Service

Information

7942

and

P3

I I

OA

OB OC

00

OE

OF'

10

11

12 13

14

JO

Z Z Z Z Z

31

Z Z Z Z

Z

32 33 34 35 36 37

38

39

3A

3B

JC

3D olE 3F'

15 16 17 18

E

Z Z

S

S S S E

19

1A

1B 1C

1D

1E

1F'

20

21

22

23

2425

26

27 28

Z

E

S

Z Z Z

S

Z

E S E S

F'e Fe

F'C

N

S S S S E E E

Fe Fe Fe

N

DE

DE DE

DE S S S

S S S

F'e

Fe

Fe S S S S S S

Fe

Fe Fe

Fe

FC

29

Z

S

Fe S S S

S

EC

Fe

7946

S S S E

S

()E

=

DATA

E~

-

DISC

FC -FAULT

ALE=F'5.JEF18A

ERROR

BYTE

CONTROLl£R

CODE

UST

IC

ERROR

Figure 4 -

N =

REGISTER

3.

P 8 Signal Source (Sheet 1 of

S Z -

NUMBER

DISC

CONTROLLER

ALL

ZERO'S

OF

3)

SEEKS

IC

STATUS

REGISTER

tOF3

4-21

Service

7942

and

P7

Information

7946

P3

I I

2A

2B

2C

20

2E

2F

30

31

32

33

34

35

36

37

38

39

3A

3B

3C

3D

3E

3F

40

41

42 43

44

45 46

47

30

Z

Z Z

Z

Z Z Z

Z

Z Z

Z

Z Z Z

Z 31 32

DE DE

S

S S

S

Fe Fe

S

Fe

S

Fe Fe Fe

DE

Fe Fe

33 34 35 36 37 38 39

3A

3B 3C 3D 3E 3F

DE

DE DE

S

S S

S

S S

S

S S S E E

FC

Fe

FC

S

S S S S S S S S

S S

S

S S S

S

FC

Fe

FC

Fe

FC

Fe Fe

DE

S

Fe

S

S Fe Fe Fe

S

Fe

S S S S

Fe Fe Fe

DE

Fe

S

S S S

Fe Fe Fe Fe Fe

DE

S S S·

S S S S S

S

E E E

E

Fe

FC

Fe

S

S S S S

Fe

FC

Fe

FC

Fe

FC

DE

S S S

S

E E

Fe

S

Fe Fe

DE

S S S

Fe

S

Fe Fe

DE

Fe

S

Fe

DE DE

S S

S

E

Fe

S S S S S S

Fe

Fe Fe

DE DE

S S

S

E

Fe

S S

S

Fe

DE

S S

S S E E

Fe

S

S S S S S

S

Fe

Fe Fe

DE DE

S S

S

S S

E E

Fe

S

S S S

S

Fe

Fe Fe Fe

Fe Fe

DE

S S

S S S

S

E E

Fe

S S

S

Fe

Fe Fe Fe

Fe

Fe Fe

DE

S S

S S S

S

S S

S

E E E

Fe Fe Fe

Fe

S S S S S

S S S S

Fe

Fe Fe Fe

Fe

Fe Fe

48

Z

Fe

S S S

FC

49

Z

DE

S S S S

E

Fe

S S S

Fe

DE -DATA E Fe -FAULT

FILE

=FSJEF19A

ERROR

DISC

CONTROLLER

CODE

BYTE

IC

usr

Figure 4 -

ERROR

REGISTER

3.

P 8 Signal Source (Sheet 2

N -

S -

Z -

NUMBER

DISC

ALL

OF

CONTROLLER

ZERO'S

of

3)

SEEKS

IC

STATUS

REGISTER

2OF3

4-22

P7

Service

Inf

7942

orma

and

PJ

r I

4A

48

4C

40

4E

4F

50

51

52 53

54

55 56 30 31 32 33 34 35 36 37 38 39 3A JB JC JD JE JF

Z Z Z Z Z Z Z Z

DE DE DE

DEi

S S S S S

S

S S

S

S S S S S S

E

E E E

Fe

FC

FC FC

s

s s

S

S S S S S S S S S S S S

S

S S S S S S S S S S

Fe

FC FC

Fe

FC FC FC

Fe

FC

DE

S

DE

S

S S

S S S

E

FC

FC FC FC

FC FC

FC

s

s s s s s s s

FC

FC FC FC

FC FC

DE

S S S S S S S S

E E E E

Fe

Fe Fe

FC

Fe

FC

DE

Fe

Fe Fe

DE DE

S

FC

Fe

s

S

FC

Fe

FC

Fe

FC

Fe

57 58 59

DE

S S S S

E

Fe

S

S S

Fe FC Fe

Z

DE

Fe

s S

S S S S

Fe FC

DE

S S S S

E

Fe

Fe Fe Fe

SA

58

5C

50

5E

5F

60

Z

Z Z

DE

S

E

Fe

s

S S

Fe Fe Fe

Fe Fe

Fe FC FC

S S

S

E

Fe Fe

S s S s

S S S S S S S S S S

Fe

Fe Fe

Fe

Fe Fe Fe

Fe

Fe Fe Fe

E

S S S S S S

E E

s s

S S

61

62

Z

DE

S

Fe

S S S S

Fe

63

64

65

Z

Fe Fe

DE

DE DE

Fe

S s s

S

Fe

FC

66

67 68

Z

S

Z

tion

7946

Z

FILE

-FSJEF20A

IDE = DATA

IE

=

ERROR

DISC

CONTROLLER

Fe = FAULT

CODE

BYTE

IC

ERROR

LIST

Figure 4-3.

N =

REGISTER

S =

Z =

DISC ALL

P 8 Signal Source (Sheet 3 of

NUMBER

OF

CONTROLLER

ZERO'S

3)

SEEKS

IC

STATUS

REGISTER

3

OF

3

4-23

Service

7942

and

Information

7946

Table

4-4.

Fault

Code List

Oct

Dec

00 00

01

02

03 04 05 06

07

40

41 42

43

44 45 47

50

51

53

57

01 02 03 04 05 06 07

32 33 34

35 36 37 39 40 41 43 47

Hex Miscellaneous

00 01 02

No error. End

of

volume.

Power

on.

Errors

03 Address bounds error. 04 Low on spare tracks. 05 Spare table overflow. 06 07 Main

20 Recoverable

21

22

23 Uncorrectable 24 Recoverable

Parameter

tenance

(or sector

Data

Errors

Marginal Marginal recover

the

bounds

track

count

data data data

data.

data

error

overflow - logs

has overflowed).

error. error error

data

error.

error

25 Marginal - ID field.

27 28 Recoverable 29 Marginal 2B

2F Unrecoverable

Unrecoverable - ID field.

data

address

data

address

Unrecoverable -

(ID field

not

data

error

readable).

Caused by

Externally

Initiated

Operations

on a utility.

are

full.

- more

than

one

try

recovered

the

- correction operation was used to

- ID field.

mark

not found.

mark

not

found.

address

on

mark

write

not

found.

operation

data.

60 48 61 62 63 64 65 66 67 70 71 72 73 74 75 76 62 77

4-24

49 50 51 52 53 54 55 56 57 58 59 60 61

63

General

faults

Self Test

that

Errors

30 Miscompare. 31

32 33

34 35

36 37

38

39

3A

3B

3C

3D

3E

3F

Failed. Passed second scan ID on Data

error

timeout

Seek

Seek/Restore

Seek -

write

Seek - drive

Seek fault. R/W

DMA byte

fault

Write Disc

controller

Disc

controller

Unit

fault.

Fault

occurred,

Verify position failure.

don't

map

to a specific

different

head.

occurred on every location.

- disc

controller

timeout

- no seek complete.

IC has

fault.

not

ready.

count

invalid.

- drive

not

ready.

IC

timeout

IC

timeout -cannot

but

unable to

- reset. reset.

identify

status

not

error

bit.

completed command.

condition.

Table

4-4.

Fault Code List (Continued)

Service Notes

7942 and 7946

Oct

100 101 6$ 102

DE~c

64-

66

Hex

40 41

42 103 67 43 115 116 117

121 123 124 125 126 134 135 136 137

77

4D

78 4E 79 4F

81

83

84~

8

<'

~.

86 9"'·

J..

93

94~

51

53

54

55

56

5C

5D

5E

96 5F

Controller Faults

Memo sequence error. No empty memos available.

Too many commands queued.

Bad

execution vector from decoder.

Byte -

underrun

bit of DDC errors register set.

DMA-In. Wrong byte count (DMA never completed).

DMA-Out. Wrong byte count (DMA never completed).

Unit Faults with Disc Controller IC (Refer to on how to

Unit U ni t

"E - Disc Controller IC Error Register", paragraph

interpret

fault

during read or write.

fault

during scan

the

P8

ID.

error

Error

byte.)

Register

Unit fault during verify operation.

Unit

fault

during correction operation. Retries exhausted on full sector operation. Track Unit Format Unit

000

error

on restore.

fault

on restore.

unit

fault.

fault

during seek operation.

4-25,

160 161 162 163 164

Il2 Il3 Ill4 115 116

70 71 72 73

74 165 117 75 166 200 201 129 202 203 204 205 133 206 207 210 211 137 212 213 214 215 216

118 76 128 80

81

1

:~O

1

:31

132

82

83

84

85

134 1:35 136

86

87

88

89

138 139 140

8A

8B

8C

141 8D 1,42

8E

Unit

faults (Refer to on how to

Write Drive not ready on Seek

retry Scan ID failed before Seek timeout

with Disc Controller IC

"s

- Disc Controller

fault

interpret

on

the P 8 status byte.)

retry

of

retry

fault

retry

fault

- 3 seconds

Seek

of Seek

Status

IC

Status Register", paragraph

Register

Seek retried Seek

retry

timed

out

- 300 msec

Format - write fault. U ni t fa ul t during read or write. Aborted command on read or write.

Disc controller

IC

timeout on read or write. Disc controller IC timeout on read or write. Disc controller IC timeout during verify. Disc controller

IC

timeout during scan ID command. Disc controller IC timeout during seek. Disc controller IC timeout during correction. Drive not ready or write Restore completed Restore - disc controller

fault

on restore.

but

no seek complete.

IC

timeout - disc controller Drive not ready on seek. Write

fault

on seek.

Restore - disc controller

IC

timeout - disc controller IC will not reset.

IC

has been reset.

IC

will not reset.

IC

4-25,

reset.

4-25

Service

7942

and

Information

7946

Table

4-4.

Fault

Code List (Continued)

Oct

220

Dec

144 221 145 222 223

224

146

147

148

225 149

226

227 230

150

151

152 236 158 237 240

159

160 241 161 242

162 243 163 244

164 245 165 246 247 250

252

253 1

166

167

168

170

71

255 173 256

174 257 175 266 300

182

192

Hex

90 91

92

93

94

95 96 97 98 9E 9F AO At A2 A3 A4 AS

A6 A7 A8

AA

AB

AD AE AF B6 CO

Unit

Faults

Read spare table timeout. Format Format -DMA Format Infinite

- Sector

count

transfer

- timeout. loop

detected

register not zero.

in Spare tables lost. Spare tables

read

failure Store spare tables failure. Read serial Write Track Zeroing Seek Copy of Write Track Track Verify failed Seek

controller

Disc Write (Write

controller

Disc

number

serial

number

sparing failed - lost spare tables.

of

spare

to deallocated spare failed

track of spare Sparing Sparing failed while

on

failure

fault

during

current

failure.

tracks

operation

to be spared has failed.

track

failed, spare allocated

cannot

obtain

second spare track.

verify

IC

error

operation

present

IC

in

overran

glitched).

Seek Complete will

write

fault.

ID-not

found Verify position Verify position Write Unit

retries

fault

on

- logs unreadable.

not

come

on scan ID command. Restore performed.

operation operation

this sector exhausted - due

count

not

valid.

logical address mapping -

failed

in

Deallocate Spares.

in

Deallocate Spares.

but

resources.

writing

of

bit

set

spare tables to disc.

spare tracks.

but

no

error

other

than

write

found.

head.)

the

DMA (IC register must have

true

after

a

reveals drive reveals drive

is is

on on

the the

to

write

not

assigned.

wrong head.

wrong cylinder.

fault.

4-26

Table

4-

S.

Diagnostic Summary

Service

7942

Information

and

7946

UNIT 0 AND UNIT 2 SELF

SELF TEST

1.

78 Sub tests. Subtests indicated on

Subtest code range:

2.

16 supplementary

SELF TEST REPORTING,

1.

Front

pa.nel

FAULT/ON

2.

Rear

panel

2-digit

• Failed unit.

• Failed FRA(s).

• Failed subtest.

SELF TEST REPORTING,

1.

QSTAT=1

2.

REQUEST STATUS message format:

• Bit 24 set

• P

1:

Most likely failed

• P2: Second most likely failed FRA

• P

3:

Failed subtest

• P7: Failed

• P8: Supplementary

error

disc controller register, disc controller

OA-68H (unit

error

condition codes.

UNIT 0 and

LINE indicator: pass/fail.

hexadecimal readout:

UNIT

FRA

condition

error

codes -

Ie

error

fault

code list,

Ie

status register.

rear

0),

0

number

TEST

panel

00-07,

Error

UNIT

data

error

of seeks, and

2-digit

88 (unit

2

hexadecimal display

code range;

byte,

2).

30-

3F.

UNIT

RUN

1.

QSTAT=l.

2.

REQUEST STATUS message format:

• Bit 24 not set.

• P7:

• P

3.

Log entries

• All

•

O~

RUN

TIME

8:

Data

run

ERROR

Fault

code list

Supplementary

e:rror

faults/data

error

log.

TIME ERROR AND

AND

FAULT

error

codes - disc controller

and

status registers.

error

codes logged in

address, status byte occurrence

FAULT

REPORTING

fault

log/data

count

Ie

error

logged in

REPORTING

log.

4-27

Service

7942

and

Inf

orma

7946

tion

UO-A5

U1-A5

U2-A5

COMPONENT

SIDE

U

(UNIn

O-DISC

DRIVE

1-TAPE

DRIVE

2

-CONTROLLER

FILE = PAMAX02A

(FIELD

A

1-DISC

DRIVE

2-DEVICE 4-POWER 5-HOST

6-CONNECTORS

1-DRIVE

2-DRIVE

3-READ/WRITE

4-DIRTY 5-HOST

7-SERVO 8-HEAD 9-CAPSTAN

5-HOST

DEPENDENT SUPPLY

DEPENDENT

MECHANISM.

CAPSTAN

MOTOR).

DEPENDENT

HEAD

DEPENDENT

ASSEMBLY

STEPPER

DEPENDENT

MOTOR

REPLACEABLE

CONTROLLER

(NOT

SHOWN)

(INCLUDES

AND

HEAD

CONTROLLER

ASSEMBLY

(NOT

SHOWNI

CONTROLLER

MOTOR

(INCLUDES

CONTROLLER

ASSEMBLY)

STEPPER

TACHOMETER)

Figure

4-4.

4-28

Field Replaceable Assembly (FRA) Locations

NOTES:

1.

SOXED

NUtolBERS

WIRE

COLOR

r---------------------------,

L-f_

I

t!,.-l-

:~~KI

~

I:m!ED

+12V

GNO

SPARE

GNO

+~V

GND +6V

GNO

+5V

J1

J

CODE

COLOR BLACK

BROWN

REO

ORANGE

YELLOW

GREEN

BLUE

VIOLET

GRAY

WHITE

B1P1

--0-

AS

FOLLOWS:

A B C

0 0 0

1 1 1

2 2 2

3

4

5 S 5 6 6

7 7 7

8 8 8

9 9 9

J 3

4

INDICATE

~

6

FAN

B1

Service

7942

,.------.,

W1P2 I J4

I I

L

______

,.------

W1P3 I J1

Information

and

7946

I

HOC

I

A5

I

.J

DISC

DRIVE

DOC

UO-A2

TAPE

DRIVE

DOC

U1-A2

POWER

SUPPLY

UO-A4

J2

POWER

SUPPLY

ASSEMBLY

UO-A4

W1P6

I

----------------------------~

FILE=PAILL09A

Figure

4-

S.

Power Distribution, Cable Assembly

WI

L.

_____

,.------.,

W1P!'i

J4

I

'-------

,.------.,

W1P8

I

JJ

'-

______

I I

DISC

DRIVE

ASSY

UO-A1

TAPE

DRIVE

ASSY

U1-A1

_

I

01

4-29

Service

7942

and

Information

7946

~FANB1

S7V420407

Figure

4-6.

UO-FRA4

(Power Supply Assembly A4), Layout

W1~

J4,

H.DC

tUO-FRA5)

J 1 ,

DOC

(UO-A2)

J4,

DOC

(U1-A2)

J4-

J3,

(UO-A 1 )

A1

J3,

(U1-A1)

and

Cable Connections

PCA-AS PCA-A2 PCA-A2 A1

4-30

Service Information

7942 and 7946

TEST

POINT

-12V +12V

PVAL-H

+5V

+12VP

NOTE:

.,.

USE

METER VOLTAGE

2.

THE

NOT

3.

MAXIMUM

5V

12V

VOLTAGE.

-11.4 +11.64

~

+4

+2.4V

. 85

11.0

TO

GND

RETURN

-12.6V +12.J6V

(TYPICALLY

5.

15V

lJ.OV

TEST

POINT

WHEN

MEASUREMENTS.

OUTPUT

VOLTAGES

ADJUSTABLE.

RIPPLE:

SUPPLY:

<5OmV

SUPPLIES: <Ioamv P-P

~~-PVAL

+5V

+12V

4.0V)

VOLT-

MAKING

ARE

P-P

$71142"08

4-7.

Figure

UO-FRA4 (Power Supply Assembly A4), Test Points and Voltages

4-31