Quantum Q250, Q280 Technical Reference Manual

Q200

Series™

Intelligent Disk Drives

Technical Reference Manual

For Q250, Q280

Disk Drives

Q200

SERIES

tm

INTELLIGENT DISK DRIVES

Q250jQ280

DISK

DRIVES

Technical

Publication

Reference

No.

REV

A

Manual

81-45528

PREFACE

This
the
technicians

integrating

Quantum
products

or

Additional

following~manuals:

Publication
Quantum

Quantum

ANSI

Quantum

Representative,

spare
Publication

manual

Q250

contains

and

and
them

reserves

without

improvements

information

No.

81-45233
81-45416

X3.131-1986

publications

parts.

No

Q280

engineers

the

in

or

81-45528

rigid

into

incurring

units

may

technical

disk

evaluating

systems.

right

to
any

previously

on

the

Title
Q250/Q280

Q200
Small

may

be

Series

Computer

be

ordered

Rev.

reference

drives.

make

changes

obligation

Q250

Disk

and

Drives.

Programmer's

System

requested

from

KL587

UL/CSA/VDE

information

Information

or

maintaining

to

sold

or

Q280

Interface

from

Quantum

and/or

incorporate

shipped.
is

given

OEM

Manual

Manual

your

Quantum

in

describing

is

intended

the

drives,

improvements

such

in

the

(SCSI)

Sales

the

same

manner

for

or

to

its

changes

as

CSA

certification

VDE

Model
material

Q250

and

shipment.

~arranty

and

representative.

Quantum

The
and
u.S.

service

product

is

the

Patents

Copyright
Q200
AIRLOCK

Printed

Series

is
in

UL

recognition

certification

and

Q280

workmanship

The

warranty

further

center

described

subject

are

1987

Quantum

and

a

registered

DisCache

U.S.A.

granted

disk

details

All

requests

herein

of

allowed

expected

granted

under

granted

WARRANTY

drives

for

a

period

includes

can

for

in

your

area.

PATENTS

is

pending

to

issue

Corporation.

are

trademarks

trademark

under

File

per

are

warranted

parts
be

obtained

service

covered

in

All

of

Quantum

Nos.
File

of

one

and

by

patent

1987.
rights

of

File

No.
LR496896-8
No.

11342-3250-1002

against

year

labor.

from

should

u.S.

be

Patent

applications

reserved.

Quantum

Corporation.

E78016

and

defects

from

your

This

date

is

Quantum

directed

No.

Corporation.

LR496896-11

in

of

a

limited

sales

to

the

4,538,193,

from

which

ii

PREFACE

TAB

L E o F

CON

TEN

T S

. .

ii

SECTION

1.1

1.2

Features
Logic

SECTION

2.1

Head

2.1.1

2.1.2

2.1.3

2.1.4

2.1.S

2.1.6

2.1.7

2.2

Drive

2.2.

2.2.2

2.2.3

2.2.4

2.2.S

2.2.6

2.2.7

2.2.8

2.3

PCB

2.3.1

2.3.2

2.3.3

2.3.4

2.3.S

2.3.6

2.3.7

2.3.8

2.3.9

2.3.10

2.4

2.S

2.6

Power-Up
Read
write

1.

INTRODUCTION .

. . . . . .

Conventions

2.

PRINCIPLES

Disk

Assembly
Base
Disk
Rotary
Headstack

Automatic
DC

Drive

Air

Electronics.

1

Disk
Simplified
SCSI
SCSI
SCSI
Power
Shorting
Flex

Functional

Power-On-Reset
Motor
Electronic
S080
Servo
Actuator
Read/Write
FYLO
DICEY
Microprocessor

Sequence/Recalibration.

Command

Command

..

casting
Stack

Assembly.

positioner

Assembly.
Actuator

Motor.

Filtration.

Format

Explanation--Block

Bus

Physical

Bus

Signal

Bus

Timing.

Requirements.

Plug

Circuit

Elements.

Control

Return

SCSI

Bus

Control,

Positioning

Circuit.

Timing

Data

Controller

Controller

Sequence.

Sequence.

OF

OPERATION

(HDA)

. . . . . .

Assembly.

..

. . .

. . . .

Assembly

(Actuator)

. . . . . . . . . .

Lock

(AIRLOCK)

. . . . .

...

.

..

. .

.

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

. . . . . . . . .

Interface.

Descriptions

.

..
. . .

Options.

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

......

..

.

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

.

..

(POR)

and

Circuit

Spring.

Controller.

AMC

and

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

Servo

.

Warm

. . .
. . .

AGC.

circuit.

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

IC,

and

IC.

and

EPROM

. . . . . . . .

.

..

.

..
..

.........

.........

.........

..

Diagram

......

...........

...........

Reset

..

. . .

.

..

xtal

........

.........

.

..........

...........

. . .

. . . . . . . .

. . . . . . . .

.

......

.

......

.......

.......

.......

.......

.

......

. .

........

.

.....

......

..
.

.....

..

..

Oscillators

..

......

.

.

1-1

1-1

1-2

2-1

2-1
2-1
2-2
2-2
2-2
2-2
2-2
2-3
2-4
2-4
2-4
2-8
2-10
2-11

2-14
2-16
2-19
2-19
2-19
2-20
2-21
2-21
2-23
2-27
2-27
2-29
2-30
2-32
2-32
2-33
2-33

SECTION

3.

ENGINEERING

DRAWINGS

.

iii

3-1

.

SECTION

4.

APPLICATIONS . .

. . . . . .

4-1

4.1

4.2

4.3

Special

4.1.1

4.1.2

Errors

4 • 2 • 1

4.2.2

4.2.3

4.2.4

Grounding,

SECTION

5.1

5.2

5.3

5.4

5.5

Maintenance
Level
Level
Connector
PCB

5.5.1

5.5.2

5.5.3

SECTION

6.1

6.2

Spare
Reference

Considerations.

-REQ/-ACK
Hints
and
Errors.
Allocating
Creating
Updating

5.

MAINTENANCE.

1

Maintenance.

2

Maintenance.

Waveforms

Special
Techniques
Test

6.

PARTS

Parts

Handshake.

for

Software

Media

Defects.

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

Replacement
the
the

Electrostatic

Precautions.

Maintenance.

and

Techniques.

Test

and

Connector

LISTS

List

Parts

...

....

List(s)

. . . . .

Driver

writers

. . . . . . . .

Sectors.
Defect
Drive

Lists.

Using

the

Discharges,

. .

. . . . . . . . .

. . . . . . . . .

. . .

. . . .

..

. . . . . . . .

Equipment

Waveform

J5

Signals.

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

Descriptions

.

.

..

..
..

.

. . . . . .

Defect

and

Lists

EMI

..

..

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

.

.........

........

. . . . . .

.

......

...

.......

.....

. .

.

.....

..

..

....

.

....

.

...

...

...

..

. •

.•

..

. .

4-1
4-1
4-3
4-5

4 - 5

4-6
4-8
4-9
4-10

5-1
5-1

5-1
5-2
5-2
5-2
5-2
5-3
5-4

6-1
6-1
6-2

iv

LIS

T

o F

FIG

U

RES

2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9

2-10
2-11
2-12
2-13
2-14
2-15
2-16
2-17

3-1
3-2
3-3
3-4
3-5
3-6
3-7
3-8
3-9
3-10
3-11
3-12

4-1
4-2
4-3
4-4
4-5

Exploded
Inside
Disk
Electronics
J1
SCSI
SCSI
Drive
General
Connector

5080
5080
Servo
Read
DICEY

Power-Up
Read
write

Printed
Schematic,
Schematic,
Schematic,
Printed
Schematic,
Schematic,
Schematic,
Printed
Schematic,
Schematic,
Schematic,

-REQ/-ACK
Buffer
In-Line
In-Line
Sparing

View

Format:

Connector.

Bus.
Bus

Startup

PCB

Conceptual
Interface

AMC

Circuit

Block

Command

Command

Circuit

Circuit

Circuit

Full

Sparing
Sparing

of

View

Timing

Locations

Sequence.

Handshake.

. . . . . .

of

Drive,

Wedges,

Block

. . . . . .

Typical

Current

Layout;

and

ADC

Waveforms

Diagram.

Sequence.

Sequence

PCB-7,
PCB-7,
PCB-7,

PCB-8,
PCB-8,
PCB-8,

PCB-9,
PCB-9,
PCB-9,

and

Field-Found

Showing

Sectors,

Diagram

Circuit

Diagram

Profile

Plug,

Block

Diagram

Circuit

. . . . .

.. ..

Board

Board

Board

Empty
of
Overflow

Parts

Sheet

Sheet

Sheet

Parts
Sheet
Sheet
Sheet

Parts
Sheet
Sheet
Sheet

Q250/Q280
Ratios.

Defective

..

Air

..
..

of

. . . . • . . . . . . . . . . . .

Terminator

Diagram.

. . . . . . .

Waveforms.

. . . . . . . . .

. .

..

. . . . .

Locations

1

· ·

2

· · · · · · · ·

3

· · · ·

Locations

1

·

2

· · ·

3

·

·

Locations

1

·

2

·

3

· · ·

Sectors.

of

Defective

Defective

......

Filtration.

and

Tracks.

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

.....

a

Signal

. . . .

. . . .

..

. . . . .

...

· ·

· · · · · ·

·

·

· · · ·

·

Line

..

and

.........

· . . . . . . . . 2

...

.

..

.

(PCB-7)

· ·

·

· · · ·

(PCB-8)

·

· ·

·

· ·

(PCB-9)

·

. . . . . .

. . . . . . . .

.....

.......

......

· . . . . . . .

· .

..

· . . .

· . . . . .

· . . . . .

· .

..

· . . . . . .

·

· ·

·

·

· ·

· ·

· · ·

·

· · · ·

· · · ·

·

·

· ·

· ·

·

· · ·

· · · · · · ·

· ·

·

Target

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

Sectors.

· ·

Sends

. .

..

Sectors

. . . . . . . .

Data

·

·

. .
.

...

. . . . . .

. .

..

.

·

·

·

·

·

·

· ·

·

·

·

·

·

·

2-1
2-3
2-5
2-6
2-9
2-10
2-13
2-16
2-17

-2
2-22
2-25
2-28
2-31
2-34
2-35
2-36

3-2
3-3
3-4
3-5
3-6
3-7
3-8
3-9
3-10
3-11
3-12
3-13

4-2
4-3
4-7
4-7
4-8

2

5-1
5-2
5-3

Test
Test
Test

Waveforms(1)
Waveforms(2)
Waveforms(3)

v

· . . . .

· .

· . . . . .

5-6
5-7
5-8

2-1
2-2
2-3

J1

Pin

Assignments.

DC

Power

Requirements

Microprocessors

LIS

and

T o F

. . . .

Buffer

.

.....

RAM.

TAB

..

. . . . .

.

L E S

...

. . . • . •

· • •

.

2-9
2-15

2-32
4-1
5-1

Available
Test

Connector

Spare

and

J5

Defective

Signals

. .

Sectors

.

· . .

· . •

4-8

5-5

vi

1.1

Features

Q250
System

and

Interface

plug-in

(PCB).
electronics
and

actuator

the

flex

The

following

throughput:

o

o

o

o

Q280

EPROM
These

except

rotor

circuit

Seeks
processed

14

KByte

and
Optional

(See

concerning
Cylinder

accessing

drives

(SCSI)

IC,

both

drives

the
are

inside

features

are

FIFO

from

the
DisCache

the

Q200

and

feature

on-board,

controllers,

models

require

spindle

use

no

motor,

contained

the

sealed

of

the

Q250/Q280

initiated

immediately--other

simultaneously.

data

SCSI

buffer

bus

increases

Series

this

data

option.)

head

skewing

sequentially

ANSI-standard,

and,

the

same

operational

headstack,

on

the

PCB. A

assembly.

drives

balances

as

well

as

data

Programmers

scheme

across

with

the

printed

adjustments.

single

enable

the

to

and

buffer

Manual

minimizes

cylinder

Small
exception
circuit

flex

circuit,

IC

high

commands

transfer

from

size

for

the
to

details

latency

boundaries.

Computer

board

All

is

mounted

data

are

of

drive.

60

of

a

heads,

data

to

KBytes.

when

on

o
o

Defect

Multiple
to

o RLL

on

management

2

Kbytes.

1,7

the

disks.

scheme

block

transfer

(run-length-Iimited)

minimizes

of

up

to

encoding

seeks

64K-1

to

spare

blocks,

increases

each

data

sectors.

with

density

up

1-1

SCSI

commands

management,

Programmable

initially
defective
to

reformat,
correcting
be

handled

of

17

bits,

relieve

error

options

and

throughout

sectors

(2)

code

in

the

or

correction,

can

data

(ECC) ,

host

detect

the

host

allow

the

be

automatically

can

be
or
computer.

three

users

product's

corrected

(3)

burst

system

and

flexible

all

of

physical

life.
reassigned
with

error

The

ECC

errors

many

tasks,

sector

ways

For

a

Reed-Solomon

detection

can

correct

of

17

addressing.

to

handle

example,

without

and

bits

such

correction

one

each.

as

defect

defects

(1)

the

error

burst

need

can

error

Q200

Series

factory-written
thermal
headstack
which
bit

sizes

1.2

Signals

level,

document,

"-ACK,"

when

other

Signal
Asserted
Asserted

use

and

of

they

signals,

and

assembly
a

track

512,

Logic

on

and

the

and

are

Type

when
when

tm

drives

in

mechanical

dedicated

densities
1024,

Conventions

the

SCSI

false

or

names

the

timing

low,

as

low

high

employ

wedges

effects

are

minimized,

servo

ensure

and

2048

bus

are

non-asserted

of

such
diagrams

as

they

on

the

a

hard-sectored

between

which

surface.

high

bytes

all
signals

might

PCB,

are

Examples

-paR

+POR

all

in

data

are

true

when

are

are

drawn

be

observed

indicated

format

sectors

tend

to

comparison

In

addition,

integrity.

supported.

or

asserted

they

are

always

to

as

on

all

misalign

with

when

at

high

preceded
show
with

the
an

follows:

with

servo

surfaces.

heads

other

drives

conservative

Logical

they

are

level.

by a minus,

signals

oscilloscope.

data

on

the

block

asserted

Thus,

linear

at
In

low

this

as

Differential

Analog

Note

example,
the
"+ACK"

that

signals

on

the

ANSI

"-ACK"

as

timing

Standard

when

"ACK"

diagrams.

listing

in

Asserted

positive

WRITE

for

the

text,

when
than

CURRENT,

SCSI,

connector

and

1-2

+READ

-READ
5 V

ANSI

pin

shows

SIG

is

SIG

X3.131-1986
connections,

positive

more

uses,

true

but

signals

for

describes

SECTION

2.

PRINCIPLES

OF

OPERATION

2.1

2.1.1
The

single
surface
brackets.

yo

'\~'ST

~:K

ASSEMBLY

for

Head
Base

piece,

the

See

r-

/

Disk

Assembly

Casting

aluminum

rest

Figure

HEADS

ACTUATOR

UPPER

AND

LOWER

MAGNETS

Assembly

of

the

2-1

alloy

drive

for

(HDA)

base

relative

casting

mechanism,

locations.

! I!

/t:tD

/'

'

/'

!

provides

PCB,

and

DISK

shock

CLAMP

MAGNETIC

a

mounting

DISK

RECIRCULATION
FIL

TER

BASE

mount

~

",

,

CASTING

/~/

FACEPLATE

Figure

2-1:

Exploded

View

MOUNTING

HOLES

~

/'

PRINTED CIRCUIT
BOARD

MOUNTING
BRACKET

2-1

2.1.2

Disk

Stack

Assembly

Three
hub
the
prevents
head
area,

2.1.3
The

permanent
the

aluminum

and

clamped

surfaces

head

surface.

and

when
Rotary

positioner

magnet

headstack
alternating
bolted
magnet

spindle

2.1.4

The

flex

to

the

plates.

or

Headstack

headstack

circuit,
positioner
entire

stack

mini-composite

steel

circuit,

flexures.

which

alloy

in

of

the

and

This
the

positioner

is

plates,

mounting

poles

base

These

off

of

assembly
and

assembly

is

at

slider-type

The

contains

disks

place.

disks,

media

only

disks

a

proprietary

hub

bonded

casting.

prevent

the

disk

Assembly

consists

rotary

balance

the

center

heads

(two

A

thin

and

wear

when
occurs
are

not

Assembly

and

a

shaft.

to

the

Resilient

surface.

positioner

each

heads,
and

a

read

for

the

Q250)

film

magnetic

lubricated

the

heads

in

the

landing

rotating

(Actuator)

design

rotary

magnet

The

consisting

single

magnets

plates
crash

the

of

heads

the

from

read/write

assembly.

of

other
the

so

mounting

mounted

actuator

are

preamplifier/write

are

metal

with

are

a

in

zone

at

full

phase

are

which,
stops
being

The

that

the

hub.

to

Whitney-style

connected

placed

carbon

contact

outside

speed.

of

upper
coil
composed

in
are
driven

heads,
head

mass

The

driver

on

is

sputtered

overcoat

molded
turn,

mounted

into

spacers,

arms

center
heads

by

the

chip.

the

with

the

and

of

are

and

are

spring

flex

motor

that
the
data

lower
to
two

to

the

the

rotary

of

the

on

2.1.5

AIRLOCK

zone,

The

is

and

dedicated
prevents
motor,
motor

it
starts

in

an
and
place.

spinning,

rotates,

2.1.6

To

DC

achieve

interference,
closed-loop
motor

3662

is

rpm.

Automatic

a

mechanical

is

covered

landing

damage

during
electronic
pulls

the

As

releasing

Drive

Motor

accurate

the

digital

dynamically

A

12 V motor

Actuator

by

zone

shipment.

return

headstack

dc

power

airflow

the

headstack.

speed

Q250/Q280

servo

balanced,

Lock

means

u.s.

Patents

for

spring

is

applied

increases,

control

uses

system,

control

(AIRLOCK)

of

locking

the

heads

When

extracts

into

the

with

a

brushless

synchronized

four

IC

commutates

and

dc
landing

to

and

minimum

pole,

the
pending
ensures

power

energy

the

motor

the

airvane

three

heads

tack
patent
data

is

removed

from

zone.

and

on

electromagnetic

dc

spindle

by

a 2

phase,

the

motor

in

the

applications.

integrity

from

the

spinning
AIRLOCK
the

disk

AIRLOCK

motor

MHz

clock.

and

rotates

coils

landing

and
the

latches

stack

in

a

The

in

at

2-2

accordance
degrees
start

up

with

around

and

signals

the

produces

motor.

dynamic

from

three

The

IC

also

braking

Hall-effect

limits

to

stop

devices
the
the

motor
motor

mounted

current
quickly.

at

120

on

contaminants
heavy

aluminum

ferro-fluid
through
are

final

the

processed

assembly
tromagnetic
reduced

by

teflon.

2.1.7

The
of

Air

Q250

11

microinches

. 3
FILTER

are

magnetic
bearing

and

Interference)

grounding

Filtration

and

Q280

MICRON

CIRCULATION

kept

housing,

core

coated

is

in

are

.

out

of

bolted

seals

prevent
or
to

a

Class

and

the

rotating

Winchester

the

drive

to

the

along

the

eliminate

100

clean

electrostatic

shaft

drives

by

base

outside

bearing
dust,

room

mounting

casting.
air

chips,
environment.
discharge

with

with

from

shaft.

a

brush

a

nominal

the

motor

Two

entering

Motor

and

oxides,

(ESD)

of

flying

inside

conductive

the

components

and

EMI

(Elec-

are

conductive

height

a

drive

Figure

2-2:

Inside

View

of

Drive,

2-3

Showing

Air

Filtration

To

keep
drives
sealed
disks
tion

filter,
shown,
equalize

the

are

with

pump

allows

internal

air

circulating

assembled

a

metal

the

enclosed

as

shown

outside

and

in

cover.

in

air

external

a

Class

air

Figure

into

within

100
During
through

2-2.

the
pressures.

the

clean

the

an

Another

sealed

drive

room
life
internal

area

free

environment,

of

the

0.3

0.3

micron

of

of

particles,

drive,

micron

the

drive

and

the

recircula-

filter,

to

the
then

rotating

not

2.2

2.2.1

Q200

seven

lists,
tains
area
data,

in

DICEY.

within
the
on

the
that
with

zation
ber,
and

At

3662
area,
passes
data

Series

tracks

serial

thirty-two

consists

and

the

data

tracks--written

disk.
identifies
the

data

area.
the

head

D),

a
rpm,

passes

under
transfer

Drive
Disk

Electronics

Format

drives

are

number
of

12

bytes

servo

In

the
areas,
In
number

checksum

a

complete
under
the

rate

employ

reserved

ID
sectors
a

preamble
of

ECC. A

wedges

a

wedge,

area

each

the

bursts,

(bursts

that

its

head

of

in

about

823
for

and

and

are

in

a

as

burst

allows
sector,

head

about

user
disk

factory

tracks
drive

test

thirty-two

and

synchronization

short

the
staggered
servo
a

wedge,

servo

track

postamble

tracks--three

sequence

and

begins
this
A

and
error

is

followed

C)

detection,

or

including

in

512

microseconds.

410

microseconds,

10 M bits/sec,

system

data.

servo

starts

ends

with

the

(refer

a

sector

wedge

i.e.,

to
uses
Each

wedges.

area,

flushes

so

they

with

with

a

preamble

by

the
and
and

The

giving

1.25

Figure

--

such

data

track

Each

512

bytes

the

ECC

times

as

don't

a

unique

servo

and

servo

number

a

short

512-byte

data

a

maximum

MBytes/sec.

2-3),

as

while
defect
con-

user

data

of

buffers

many

overlap

qual
burst.
synchroni­track

num-

(bursts

postamble.

data

itself

as
area

As

B

user

2.2.2

This
to

simplified

section

the

Simplified

summarizes

more

detailed

block

Explanation--Block

sections

diagram

the

of

operation

that

the

system.

2-4

Diagram

of

follow.

the

drive,

Refer

to

as

an

Figure

introduction

2-4,

a

SERVO

TRACKS

I /

-~~~-j

/

+

STo~A~

/

10i

----T----- -

TO

CENTER

OF

DISK

1

SERVO & DATA

TRACK

LAYOUT

TRACKS

QUAL.
AREA

50us

PRE

AMBLE

rr---w...---I--<- /

'-

'-

'-

'-

'-

S
Y
N
C

PRE
AMB

~

I e

'-

'-

'-

'-

TRACK

NO.

/

105

/

/

/

/

104

/

/

/

/

LE

'-

\

103

102

101

S

Y
N
C

'-

'-

'-

'-

'-

P

0

S

T

'-

~

512

452us

DETAIL

OF A BURST

CHECKSUM

HEAD

NO.

{

SECTOR

c=J

P

A&C)

B&D)

E

0

C

S

C

T

DATA

BYTES

(BURSTS

NO.

(BURSTS

[

[

LOGICAL~

TRACK

NO.5

DETAIL

OF

ONE

SECTOR

12

BYTES

Figure

2-3:

Disk

Format:

Wedges,

2-5

Sectors,

and

Tracks

Power-On

Voltages

low,

as

on-reset

until

At
the

the

initial

inner,
amplitude
calculates
optimize

may

be

when

the

(PaR)

circuit

voltages

power-on,
outer,

measurements

and

stores

seek

-------,

-------,

and

I

I
I
I

applied

power

are

the

and

settle

in

any

has

failed
resets
high

drive

middle

are

made

adaptive

times.

sequence.

the

enough

is

tracks;

and

gain

ELECTRONIC

RETURN
SPRING

When

or

has

just

major

and

circuits

stable.

recalibrated:

at

each

from

these

parameters

2MHz

UB

the

been

location,

the
that

RESET

uP

OTHER

CIRCUIT

dc

voltages

applied,

and

keeps

the

actuator

servo-burst

microprocessor

are

later

the

them

seeks

+12V

+5V

are

power-

reset

used

to

to

R/W

HEADS

______

HEAD

DISK

ASM

(HDA)

PRE-AMP

WRITE

DRIVER

...J

Figure

2-4:

Electronics

2-6

Block

ALE.

-WR.

-RD

*64KB

WITH

DISCACHE

Diagram

50BO

12MHz

SCSI

BUS

TO

HOST

Architecture
A

standard

Series

for
ferent

without

drive.

drives

EPROMS

DisCache.

8-bit

with

microprocessor

An

8031

it.

are

Firmware

used

Special

is

for

used

the
EPROMs

operated

for

is

in

Q250

drives

a
and

may

at

without

plug-in

Q280,

be

used

12

MHz

32

and

for

controls

DisCache,

K X 8

for

drives

custom

each
an

EPROM.

with

applications.

Q200
8032
Dif-

and

communication
MAD
controller
dynamic
of

serial
generates

SCSI

(multiplexed

RAM

is

the

IC,

RAM

(4

KBytes

DMA

controller,

conversions,

the

Bus

Operations

Communications
bus.

can
reconnect

Before

The

play

the

the

interface

and

disk
accumulated
read

the
option),
bus.
error

from,

data

Users

is

data

is

transferred
detected,

Servo

between

address/data)

manages

(64

KBytes

with

ECC

with

role

arbitration

is

in

buffer

is

checked
can

select

the

access
for

DisCache)

performs

handles

syndrome.

the

host

is

implemented

of

initiator

written

RAM

also

stored

with

through

the

via

the

major

bus.

to

drives

all

and

or

functions.

to,

a

(via

DMA
in

the

error-correcting
the

action

MODE

circuit

the

with

is

reserved

serial

RLL

encoding

other

with

target,

full

transfers).

RAM.

5080

to

SELECT

components
DICEY, a
buffer,

DisCache).
to

parallel

SCSI

a

5080
and

sector

After

via

DMA,

be

taken

command.

proprietary

which

for

Q250/Q280

and

decoding,

devices

SCSI

performs

of

incoming

As

a

full

code

then

in

the

is

over

is

16

The

upper

and

parallel

is

over

Controller

disconnect/

the

disk

sector

(at

the

on

to

event

the

data-

KBytes

2

use.

and

the

SCSI

is
is

user's

the

that

8-bit

of

KBytes

DICEY
to

SCSI

IC

data

being
read,

SCSI

an

that

is

While
tion
position
microprocessor
tion
output
New
bursts,
decelerates,
seek

As

the
the
processor
tude,

track-following,

are

stored
at

DAC

track

(digital-to-analog

is

converted
and

forming

in

the

servo

AMC
servo

bursts

(amplitude

ADC
reads

if

possible.

in

buffer

all

times.

immediately

sector

a

closed

the

actuator

shortest

pass

measurement

(analog-to-digital

head

track

When a

to

a

numbers

time.
under

position

Once

and

RAM--the

starts

converter)

high

current,

are

loop.

via

the

the

from

the

head

sector

microprocessor

READ

a

or

seek

read

The

microprocessor

head

head,

their

circuit),

converter).

the

is

on

2-7

numbers

WRITE

by

via

which

on

the

position

and

burst

track,

of

knows

command

commanding

the

MAD

drives

fly

from

DAC

amplitudes

placed

When

with

the

the

the

current

the

exact

arrives,

the

head

bus.

the

The

actuator.

the

DAC

servo

accelerates,

to

achieve

are

measured

on

the

MAD

seeking,

the

highest

microprocessor

posi-

the

posi-

then

the

bus

micro-

ampli-

head

by
by

keeps
position
each
bursts

side

the

A

head

so

of

and

following

that

the
D

on

the
data

logical

the

amplitudes

track

are

track

track

exactly,

of

the

equal.

a

are

two

For

kept

by

adjusting

servo

example,

equal.

bursts

in

the
written
Figure

head

on

2-3,

There
Each
amplified

(automatic-gain-control)
differentiated
a
data
drop-outs
for

write
The

(under
the

2.2.3
A

necting
standard
Universal
the
AMP

(without
should
backwards.

is

one

head

pulse

and

every

preamplifier/write
head,

50-pin

mating
receptacle

can

first

detector.

clock

rare.

magnetic

command

which

SCSI

connector

to

the

SCSI

Header

connector

strain

not

be

head

either

by
to
signals

of

writes
Bus

standard

single-ended

PIN

relief),

used

for

each

read

the

preamplifier

find

RLL

the

connector

the

A

phase-locked

for

1,7

transition

driver

microprocessor)

magnetic

Physical

is

provided

improperly.

1-499508-2
due

to

surface:

or

write.

amplifier.

zero
DICEY.

encoding

Interface

SCSI

bus.
non-shielded
and

or

equivalent.

the

crossings,

loop

allows

on

the

chip

transitions

at

position

See

has

a

The

(with

danger

four
chip

Careful

inside

strain

on

When

in

That

circuit

1.33

disk.

and

Figures

connector

key

slot

recommended

Unkeyed

of

plugging

the

reading,

the

output

and

converted
derives

design

data

the

HDA

sends

on

the

J1

on

2-5

to

relief)

Q250,

the

HDA,

is

filtered,

makes

bits

selects

current

disk.

the

and

is

prevent

mating

or

mating

the

six

on

output

then

PCB
used.

connector

by

to

synchronized

drop-ins
to

be

the

reversals

for

2-9.

installing

connector

PIN

1-746195-2

connectors

the

is

an

then

pulses

stored

head

con­The

J1

is

in

Q280.

AGC

by

or

to

a

is

A

50-conductor
with
of
together

reflections,
same
satisfactory

connected

is

a

100

bus.

20

minimum

ohms

using

to

feet

flat
conductor

+/-

10%

a common

cables

Table

(6

2-1
transmission
ground;

meters),

cable

is

recommended.

of

different

gives
pin

a

or

size

cable.

J1

quality,

25

length

a

25-signal

of

pin

is

left

28

AWG
SCSI

To

minimize

impedances

assignments.

all

open.

suitable

2-8

twisted-pair

and

a

devices

discontinuities
should

odd

pins

Maximum

for

use

ribbon

characteristic

are

daisy-chained

not
Note
except

in

that

total

a

cabinet.

be
pin

and
used
to

25

cable

cable

impedance

signal

in

the

achieve

are

length

CENTER

KEY

SLOT

Ground
1

3

5

7
9
11
13
15
17
19
21
23

25
27

29
31
33
35
37
39
41
43
45
47
49

DDDDDDDDDDDDDDDCCCCCCCCCC
DOCOCDOCCCCCCDCCCCCCCCCCC

CONNECTOR

Figure

Table
Signal
2

4
6
8
10
12
14
16
18
20
22
24

26
28
30
32

34
36

38
40
42
44

46
48

50

Name

-Data

-Data

-Data

-Data

-Data

-Data

-Data

-Data

-Data
Ground
Ground
Ground
Open
Terminator
Ground
Ground

-ATN
Ground

-BSY

-ACK

-RST

-MSG

-SEL

-C/D

-REQ

-I/O

PCB

2-1:

Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit

POSITION

2-5:

0
1
2

3

4
5
6
7
P

Jl

Pin

Jl

(-DBO)
(-DBl)
(-DB2)
(-DB3)
(-DB4)
(-DB5)
(-DB6)
(-DB7)
(-DBP)

Power

#1

Connector

Assignments

(TERMPWR)

INDICATOR

2-9

2.2.4

All

signals

2-6

for

physical

provided
the

terminators

SCSI

are

a

typical
end
as

terminators.

Bus

of

Signal

true

circuit).

the

bus.

plugged

low

Descriptions

and

use
A

Three

Drives

in.

See

open

collector

termination

resistor

are

shipped

Figure

CAUTION

is

networks

2-9

for

drivers

required

from

locations

in
the

(see

at

sockets

factory

each

on

Figure
are

with

the

PCB.

5'1

Only

are

all

packages).

the

current

to

Plug-in

plugged

with

the

about

r---------

the
allowed
other

bus

carry.

a
PCB.

the

__

two

to

devices

If

drivers

from

terminator

in

correctly.

dark

band,

All

correct

~~----

devices

have
the

may

the

at

the

terminators:

on

the

bus

additional

be

damaged

+5 V supply

physical

(unplug

terminators

because

than

CAUTION

packages

On

and

must

terminators

orientation,

TERMPWR

__

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

each

face

face

(PIN26)

are

package,
the

consult

ends

remove

all

the

48

polarized,
the

"1"

same

5V

of

the

terminators

three

are

they

rnA

will
they

and

pin

1

that

is

way.

Figure

SCSI

terminator

not

removed,

sink

are

must

is

be

marked

screened

If

in

doubt

2-9.

bus

from

more

rated

on

5V

~----~----~--------~---------------+--~------4---~------1

~----~----~--~----~---------------r----------T---~----~

DEVICE

WITH

TERMINATOR

Figure

"----------..

2-6:

SCSI

DEVICES

Bus.

-SIGNAL

GROUND

-------)

V

WITHOUT

Typical

2-10

TERMINATORS

Circuit

of

a

Signal

DEVICE

WITH

TERMINATOR

Line

Each

Q250/Q280

bus

driver

has

the

following

output

characteristics:

Each

True
False

signal

(Signal

(Signal

received

characteristics:

True
Maximum
False

Minimum
SCSI
Up

tion

to

Bus

eight

is

Information
low a defined

byte

a
that

of

total

comprise
described

(Signal

total

(Signal

input

Signals

devices

allowed

transfers

-REQ/-ACK

information

of

18

logic
an

briefly

-BSY (BUSY). An

used.

Asserted)

Non-Asserted)

by

Asserted)

input
Non-Asserted)
hysteresis

can

between

on

can
signals:

8-bit

DATA

below.

"oR-tied"

=

0.0

to

0.4

=

2.5

to

the

load

be

supported

only

the

Q250

=

0.0

=

-0.4

=

0.2

two
SCSI

or

Q280

to

=

2.0
V

SCSI

DATA

0.8

mA

to

dc.

on

devices

BUS

(request/acknowledge)

be

transferred

nine

BUS

signal

control

with

that

with

parity.

indicates

V

5.25

must

V

at

5.25

the

signals

dc

at

have

dc.

0.4

SCSI

at

are

handshake

each

Each

48

mAo

V

dc.

the

following

V

dc.

V

dc.

bus,
any

but

given

asynchronous

handshake.

and

nine

of

the

that

the

communica-

time.

and

protocol.

There

signals

signals

bus

is

input

fol-

One
are

is

being

-SEL
a

-C/D

whether

indicates

-I/O
direction
tiator.
also

-MSG

(SELECT).

target

to

reselect

(CONTROL/DATA). A

CONTROL

CONTROL.

(INPUT/OUTPUT).

of

data

Assertion

used

to

distinguish

(MESSAGE). A

A

or

-REQ (REQUEST). A
a

-REQ/-ACK

-ACK

(ACKNOWLEDGE).

acknowledgement

data

transfer

for

signal

an

initiator.
signal

DATA

information

A

signal

movement

indicates

signal

signal

A

signal

a

-REQ/-ACK

used

by

driven

driven

on

the

input

between

driven

driven
handshake.

driven

an

initiator

by a target

is

on

by a target

DATA

to

BUS

the

SELECTION
by a target
by a target

by

data

transfer

the

with

initiator.

and

an

initiator

to

select

that

DATA

BUS.

that

respect

RESELECTION
during
to

the

indicate

to

handshake.

a

target

indicates

Assertion

controls

to

This

MESSAGE

a

indicate

an

ini­signal
phases.

request

or

by

the

is

phase.

for

an

2-11

-ATN (ATTENTION). A
ATTENTION

condition.

signal

driven

by

an

initiator

to

indicate

the

-RST

(RESET).

-DB(7-0,P)
signal,
has

the

that

highest
significance,
defined
the

Data

(i.e.,

as

signal

parity

a
generate
have
valid

parity

during

TERMPWR.
terminations
event

of

2.2.5

Delay-time
signal
Thus,
without

conditions

the

considering

An

(DATA

form

priority

and

one

when

is

non-asserted.

-DB(P)
system
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