IBM 7074, 7000, 7080, 7070, 7090 General Information Manual

General

Information

Manual·

IBM IBM

1301

7000

Disk

Series

Storage

Data

with Processing Systems

Preface

This

manual

tory information on

Storage Since

the length length addressing schemes, out,

and

tempt

to give specific details for these areas; the variations

are bulletin for systems the

7631 File Control has tions section of this manual. reader the

major

is

intended

with

IBM

7000 series

7000 systems include

systems

system

(7070,7074,7090) (7080),

data

transmission. This

described in a

each

system. Information common to 7000

in

the operation of

to provide general introduc-

the

use of

the

IBM

Data

Processing Systems.

both

and

a variable

minor variations occur

track

capacity, core storage lay-

manual

separate

IBM

1301 Disk Storage

the

1301 Disk Storage

been

included

It

is assumed

has a practical working knowledge of one of

IBM

data

processing systems.

the

in

fixed

does

the

1301 Disk

word word

in

the

not

at-

and

Opera-

that

the

MAJOR

REVISION

This edition, and

IBM

N22-0035, N22-0039,

Address comments concerning this

IBM Corporation Customer Manuals, Dept. 298 P.O.

Box

Poughkeepsie,

(October, 1962)

Form

D22-6576-3, obsoletes Form D22-6576-2,

Technical Newsletters, Forms N22-0029, N22-0031,

and

N22-0061.

390

N.Y.

by

International Business Machines Corporation

manual

to:

Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Magnetic Disk Recording. . . . . . . . . . . . . . . . . . . . . . . . . . .

Functions

Operations

Control Sense Write Read Checking

Shared System Operation. . . . . . . . . . . . . . . . . . . . . . . . . . .

Instruction Times Access Motion

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

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

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

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

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

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

Time.

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

Control Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Power-On Switches

and

Lights. . . . . . . . . . . . . . . . . . . . . .

Error Recovery Procedures. . . . . . . . . . . . . . . . . . . . . . .

..

" 10

10 12 13 15 16

..

17 18

..

18

..

20

..

20

..

21

5

5 9

IBM

1301 Disk Storage

IBM

1301

Disk

Storage

High-speed magnetic disk storage provides large external storage capacity to supplement internal core

The

IBM

storage of a computer system. Storage

and

its associated

IBM

7631 File Control pro-

1301 Disk

vide very large storage capacity, fast access time to

the

disks,

and

data recorded on

the ability to handle

fixed or variable length records.

Significant advantages are:

1.

Lower cost

2.

Entire program libraries contained in readily

per

character of storage.

accessible form.

3.

Access to any program or active file

in

50-180

milliseconds.

4.

Table storage.

5.

Simplification of program scheduling.

6.

Ability to

dump

and

recover files into or from

core storage rapidly.

7.

Customer control of addressing schemes

and

record length format.

8.

Improved checking techniques - more reliable data

recording.

The

1301

Disk Storage

are available for use with

and

1410

7090,

The

1301

Data

Disk Storage

and

the

7631 File Control

the

IBM

7070, 7074, 7080,

Processing Systems.

is

available in two models:

:Model 1 - single module, providing capacity for

28,000,000 (7080)

characters-or,

using

packed format, 43,300,000 digits.

Model 2 - two modules, providing capacity for

56,000,000 (7080) characters - or, using packed format, 86,600,000 digits.

The

7631 File Control

1-

Model

for use with a 1410 system

Model 2 - for use

is

available in four models:

with

a 7000 system (7070,

7074,7080, 7090)

Model 3 - for shared use with a 7000 system

and

a 1410 system

Model 4 - for shared use with two 7000 systems

Index or Reference Point

~

250

Data Tracks

Within This Area

Figure

1.

Magnetically

Data

are stored as magnetized spots in concentric

tracks on each surface of

Coated

Disk

the

disk

(Figure

1).

There are 250 tracks for the storing of data on each surface. The

tracks are accessible for reading and writing

positioning

the

read-write heads between

the

by

spinning

disks.

The read-write heads are mounted. on an access mechanism which has 24 arms, arranged like a comb the disks.

(Figure

(No

2),

that

move horizontally between

vertical motion

is

involved.) write heads are mounted on each arm. One of heads services while

the

lower disk. Thus, it is possible to

other

the

bottom surface of the

head

services

the

top

read

teeth

Two

upper

surface of

or write on

on

read-

the

disk

the

either side of a disk.

Head

services

Head servi bottom of

ces

surface

upper disk

Magnetic Disk Recording

The

magnetic disk is a thin metal disk coated on sides with magnetic recording material. Twenty-five disks are mounted on a vertical shaft; they are slightly separated from each other to provide space for movement of read-write assemblies. spinning per

the

minute.

disks

at

a maximum of 1790 revolutions

The

shaft revolves,

both

the

Figure

2.

Head

Arrangement

Introduction 5

The

magnetic disk tively. track, the old corded. desired; until

provides external storage capacity ternal core storage of a computer. Disk storage has a major advantage, however, in tained in random is, faster access to

the track records be data arrangement ments. Addresses must track also, space separate address for

fining areas. for monitors 40 associated can data of

25 magnetic disks Of store data; of alternate surfaces, one is a format surface, one is a clock surface The contain 250 concentric tracks reading

Cylinder Concept

Since aligned one above the tracks

(Figure in available without electronic for one access mechanism setting, as characters (7080)

bottom to

Each

time

is

The

recorded

data

remain

written

Disk storage, like trays of cards or magnetic tape,

Although

arranged

can

and

the

A format track is used to provide a means of de-

be

track format as often as

the

A disk storage

the

data

anyone

The

over.

the

1301 are program-addressable, providing

access to

the

is

fixed,

and

the

to suit

be

stored on

within

the

must

records.

and

monitoring

the

data

written

user.

25 disks, 20 disks

the

(Figure

storage surfaces

and

writing.

the

heads

can

4).

Thus,

of

the

head

tracks

the

top

data

surface can

new

information

erased as

any

total

the

number

the

individual records to

be

and

tracks.

and

module

and

other

and

the

be

considered as a cylinder of tracks with

250 cylinders, 40 tracks of

any

switching is necessary.

are

numbered

of

the

new

data

may

recorded

record or group of records

record). number arrangement

needs of

the

provided

record areas, as well as

the

data

rewritten to describe

its associated access mechanism.

3).

disk tracks

other,

the

available.

cylinder (corresponding

in

of character positions of

of characters

the

track in any convenient

limitations of track require-

be

provided to identify

in

address, record,

In

the

1301, one format track

tracks.

required

is

comprised of

(40

surfaces)

ten

surfaces, six

The

other

and

the format surface

that

the

access mechanism

further

sequentially, from

be

used repeti-

is

stored on a

information

be

read

as often as

the

tracks of a disk

to

supplement in-

that

all records con-

as to

the

number

per

record can

using system. Thus,

the

computer;

the

form of gaps to

The

format

the

to

suit

the

are are

two

are

accessible for

are

mechanically

vertical alignment of

access motion; only

For

many

as 112,000

is

re-

(that

the

areas

and

gap

track

desired

the

needs

stack of

used used as

not

used.

each

placed

data

are

example,

the

to

the

of

to

Figure

3. Disk Surfaces

40 heads, 00 to

(000) to large storage areas for reference tables, be

conveniently stored in a cylinder of tracks number duce access time to a minimum.

optional feature, the cylinder mode of operation, read tracks in one operation.

Data

The track. track to a specific overall recording capacity. All tracks recording area cannot a provide a means of identifying system, or a home address (

One

Cylinders

Figure

of adjacent cylinders. This technique will re-

The

cylinder

or write a cylinder,

Tracks

basic fixed recording area of

The

are

number

of

250

4. Cylinder

39),

starting

the

innermost cylinder (249).

arrangement

physical make-up of

equal

in overall storage capacity.

of character positions must

Concept

at

the

outermost cylinder

of tracks also permits

(or

part

the

be

used to store data, however;

the

track

HA).

To

Thus

the

data

or

of a cylinder) of

1301 is track limits

be

provide

--1-

__

the

The

set aside

to

the

random

20 Data

Disks

(40 Surfaces)

1

__

entire

using

-

with

can

in a

the

to

data

the

data

to

6

access to any record on the track, additional character positions must a record address are required for gaps

be

used for each record on

(RA).

Additional character positions

(G)

to separate addresses

the

track, or

and

records. Since the tracks are circular, an index point

I)

must

be

(

used to indicate

of the track. Therefore, each of the 10,000

the

beginning or

data

the

tracks

end

must have an index point, one home address, a record

the

track,

and the rec-

by

the

and

file

address for each record stored on necessary gaps to separate ords (Figure

INDEX

POINT

The

index point of the track is the reference point of the track, the end of the track.

that

5).

is,

it

indicates

The

the

address

both

index point

and

the beginning

is

used control in conjunction with its various modes of operation.

HOME

ADDRESS

There is one home address for each of

tracks.

The

(HA)

home address follows

the

index point

the

10,000

and

consists of two parts called home address one (HAl) and

home address two (HA2).

HAl:

This portion of the home address is the track

number.

the customer.

(

0000-9999) indicating the physical location of the track within sequentially, beginning most cylinder, track number through ing

the

HAl

is prerecorded; it cannot be written The

track number

the

module.

at

the

cylinder to track number 0039, represent-

40

data

tracks of the outermost cylinder. The

is

a four-digit number

The

tracks are numbered

the lowest track of

0000,

and

continuing

the

by

outer-

up

numbers continue with the lowest track of the adjacent cylinder, track number track number

0079. Continuing through each of cylinders in a like manner, is

the top track of

the method of numbering, adjacent tracks on disk always differ determining cylinder ber

and

product of

the

by

the

cylinder number, the track

the

by

40.

track number for any track within any

simple formula: Given the

cylinder number number. For example, for cylinder head number

241 X 40

20

the track number is:

= 9640; 9640 +

0040,

up

the

cylinder to

the

last track number, 9999,

innermost cylinder.

With

the

This provides a means of

head

number

and

40, plus the

20

= 9660.

number

241

the

this

same

num-

is the

head

and

Also, with the track number known,

and

head

number dividing the track number

number can

by

cylinder number; the remainder

be

40; the quotient is

is

For example, given the track number,

40

0590 +

Thus, the cylinder number is

30.

HA2:

The

= 014 with a remainder of 30.

is

014 and

second portion of the home address is

called the home address identifier. This portion of

address further identifies the track to

HA2

is

written

characters

that

by

the user

can

and

consists of two or more

be

numeric, alphabetic, or special

the

determined

the

head

0590,

the

head

the

using system.

cylinder

by

the

number.

number

the

characters, depending upon the requirements of the using system. Two characters are required for

HA2;

even though only two characters are compared during

address verification operations, additional characters can

be

used as a convenience for fixed word length

systems.

HA2

can

be

written to serve any convenient purpose.

It

can

be

used as a coded

be

used to identify or tag a category of records, such

file

protect device or

it

can

as receipts, withdrawals, payments, inventory, etc.

HAl

and

HA2

can

be

treated as one six-position ad-

dress

that

corresponds to a six-position key of record,

part

number, policy number, account number, etc.

RECORD ADDRESS

The

record address consists of six or more characters

that

can

be

numeric, alphabetic, or special characters.

It

is

used to identify the individual record on to the using system. A record address is assigned written scheme; address of dress tional order. and

(single record) order, need not

ters tions) can the 7080

by

the

user to

it

need not have any relationship to the home

the

track where

is

transmitted to the

The

the record address, used

The

record address normally consists of six charac-

and

even though the first four (high-order posi-

be

alphabetic or special characters

and

7090, only

fit

any convenient addressing

it

is

written, since an ad-

file

control for each func-

home address, used for seek orders,-

in

the prepare to verify

be

related in any way.

the

numeric

the

bit

positions of

track

and

with

these characters are compared during address verification operations. All bits of the' fifth ters are compared during address verification.

and

sixth charac-

The

Index Point

~

-{

Figure

HA 1

~

5. Track Layout

GAP

HA 2

GAP

Record

Address 1

GAP

Record t

Record

Address 2 Record 2

GAP

Introduction 7

7070

and

7074 use

only the first six digits

GAP

To

distinguish between addresses are written between address gaps contain check characters ization information required for

ten

digits for record addresses,

(high

order)

are verified.

and

records, gaps

and

record areas.

and

internal synchron-

proper

machine opera-

but

The

tion.

Data

are

read

and

written on a track characters or "bytes" serially character.

The

8-bit mode permits

by

in

6-bit or 8-bit

bit

and

the

use of packed

serially

by

format feature (packing two 4-bit digits into one 8-bit character) on the ture.

Data

characteristics of disk storage are shown

in

Figure

6.

system using

that

fea-

1301

by

any

Since there are 250 tracks on each of the 40 disk

storage surfaces

a module, 10,000 addressable

data

in

tracks are available in each module.

Format Track

Before

the

disk module can

be

used for reading or writing, certain preparative activities are necessary. These activities can trol panel for unit record machines or

be

likened to

the

wiring of a con-

to

the

housekeeping preparations for a program. Preparations involve writing a format track or instruction) for each cylinder of the module. format track permits tain limits, how cylinder is to established, and

control for the subsequent reading or writing of

data

for

that

be

the

cylinder.

the

storage space of the tracks of a

allocated, identified,

format track provides a fixed format

(by

means of a command

user to designate, within cer-

and

used. Once

To

alter

the

fixed format

The

and

control for a

new

The organized gramming is used to transmit

to

age a format track are given

anyone

format track

data

used

in

the

addressed format track. Details on writing

of

the

250 cylinders requires

be

written for

to

create a format track

core storage as a

the

under

that

cylinder.

data

from core stor-

Write

Format

must

record. Pro-

that

first

Track

be

Operation.

The

writing of

under

complete control of format remains fixed until unintentional changes to

and

the

layout of

the

format track is

the

user. Once written,

it

is rewritten. To prevent

the

format tracks, each

the

module is provided with a two-position key-lock switch. A format track cannot key-lock switch is placed

the

mally

Track Capacity

Each bit

switch

track

character positions available for

is

in

a module has 2840 six-bit or 2205 eight-

the

in

READ

the

written unless

WRITE

position.

the

position; nor-

recording of

the

be

information. Character positions necessary for home

the

address two, considered, however,

record addresses,

in

determining character positions available for eral,

the

track area available to store total track capacity less sary for addresses

The

track capacity for

mum

when writing a single record on

and

the

character positions neces-

gaps.

any

tracks containing a single record,

and

the

records.

the

system is

the

gaps must

number

records is

at

the

track.

In

be

of

gen-

the

maxi-

For

track capacity

for each system is:

System

7070 and 7074 7080 7090

6-Bit

2,780 2,800 2,796

8-Bit

2,150 2,165 2,160

Packed

4,310

4,330

Does not apply

Characteristics* 7070-7074 7080 Maximum Characters per Track

Maximum Characters per Maximum Characters per

(2 Modules)

Maximum Characters per File Control

(5-1301's)

Character

* Figures represent

Figure 6.

8

Rate

Data

Cyl

inder

Disk

Storage

maximum

Characteristics of Disk Storage

uti! ization of space (each track written with a single record)

55,600,000

278,000,000

Six-Bit Mode

2,780 2,800

111,200 112,000

56,000,000

280,000,000

90,100 char/sec

7090 Packed

2,796

111,840 172,400

55,920,000

279,600,000

86,200,000

430,000,000

7070-7074

4,310

140,200

digit/sec

Unpacked

2,150

86,000

43,000,000

215,000,000

70,100

char/sec

Eight-Bit Mode

7080

Packed Unpacked

4,330

173,200

86,600,000

433,000,000

140,200 70,100

digit/sec

43,300,000 43,200,000

216,500,000

2,165

86,600

char/sec

7090

2,160

86,400

216,000,000

70,100

char/sec

Functions

The

function performed

1301 Disk Storage,

based

are and

on

orders, defined as follows:

and

the

execution of instructions, commands,

Instruction: An instruction

that

tion essing unit to perform a specific function.

is decoded

Command: A command

that

is

decoded

perform a specific function.

the

use

decoded in this case)

term commands.)

Order:

An order is control-coded information

and

executed

to

perform a specific function.

by

the

using system's

and

executed

is

executed

by

a control

the

7631 File Control,

data

channel

is

system-coded informa-

by

the

central proc-

system-coded information

by

the

data

channel to

(The

7080 system does not

that

unit

(file control,

In the following description the word "command" means "instruction" when applied to the

The

file control can execute

mands

plicable

which

Read circuits in mission of puter mand control to age

transmit orders to

Orders

Orders are transmitted to

command of

are normally transmitted.

the information as

of using this file control, although they

code address information is not required, of of

channel as BCD characters. accepts the

(read,

data

the

and

system

causes transmission of status

and

Transmission of orders to

the

command is

are initiated

Orders normally consist of a two digit operation

and

the

operation code only. Figure 7 shows

the

order.

Orders

the

order (operation code, access

write, sense,

processing system defines

four commands are issued to the file control.

write commands set

the

connecting

data

between

through

the

computer to indicate status of disk stor-

file control.

the

eight characters to define addresses.

are

transmitted from

digit portion of

the

The

the

file control.

computer in

an

order, decodes it,

the

same for all computer systems

may

be

anyone

and

up

data

channel to

disk storage

file control.

control command

the

file control

the

same

The

file control recognizes

the

file control as a result

the

different.

the

The

the

first eight characters of

and

7080

system.

of four com-

control) .

necessary control

The

data

method

the

computer's

7631 File Control

module number,

The

the

method

permit

and

from

manner

and

order consists

trans-

the

com-

sense com-

the

is

used to

by

a control

as

executes it.

by

which

When

the

make-up

ap-

by

file

data

Operation Code

Access and Module Number

G'

'Xx'

'XX

Figure 7. Order

and

the

first four positions of

the

ninth

in

and

xxxxxx'

"'~d

Add,""

the

address)

tenth

characters of

the

Operation Code: A two-digit code

operation to

is

always numeric. required for mode, eight-bit mode,

be

performed. This portion of

The

operation code is all

the

following orders:

and

no

release.

Access and Module Number: These two positions of

the

order, always numeric, specify

the

operation will take place.

Record

gives type of operation

Operation Signals

Since disk storage operation takes advantage of interrupt feature of

generated to provide a communication link the erated

Attention: Indicates

operation has successfully positioned

anism head.

End: Indicates

operation. This signal can indicate

mission of

cate

operation.

or

Home Address: This portion of

the

home or record address, depending

that

is

to take place.

the

7000 series systems, signals are

file control

to indicate a specific condition exists, are:

at

the

and

the

computer.

that

specified location

the

successful completion of

an

order to

successful completion of a

the

The

a previously given seek

and

selected

the

file control, or

Unusual End: Always indicates

operation. This signal can indicate been

sensed

other check condition has occurred, or

that

cate

occurred.

Stop: Indicates

of a

read

the

record definition

the

from

and

from

during a read

an

unsuccessful

that

or. write field.

sensing of a group mark in a 7080 system; word

count

or write operation, or any

attempt

the

computer has sensed

The

word

in a 7070 or 7074 system;

equal

zero in a 7090 system.

that

to

stop signal results from

and

all bits

order.

that

specifies

operation, six-bit

module in which

signals, gen-

the

access mech-

the

successful trans-

it

read

an

unsuccessful

an

it

might

transmit

the

order

that

the

order

upon

the

between

desired

an

can indi-

or write

error has

indi-

data

has

the

end

is

Introduction 9

Operations

The four basic commands used to perform all disk

and

file

storage write

and

control operations are: control, sense,

read.

Control

The

7631

File Control will decode

13

orders transmitted from the computer

trol command.

The

7631

decodes accepts address information, performs the designated function, signal to the computer. file order.

and

then transmits

control sends

It

then performs the seek,

the

In

the case of a seek order,

END

signal after decoding

tion of the seek operation, sends an to the computer.

The orders consists of two or ten characters. operatIons where addresses are not required, only a two-digit operation code Orders requiring

the

is

two digit operation code only are:

no operation, release, six-bit mode,

The

orders, with their mnemonic code

numeric operation code are shown in Figure 8.

No Operation (DNOP-OO)

This order requires only The order

is

accepted

by

the

the convenience only. No function 7631

for this order.

Order

No

Operation Release Eight-Bit

Mode

Six-Bit

Mode Seek Prepare

to

Verify,

Single

Prepare

to to

Prepare

to

Prepare

(Optional

Prepare

to Set Access Prepare

to to

Prepare

Figure

Write, Verify, Verify,

Feature)

Write

Inoperative Verify, Verify,

8.

Table of Orders

Record

Format

Track with Cyl

Check

Track with Addresses Home Address

inder

No

Operation

Addresses

and

execute any of

by

the

con-

the

transmitted order,

an

END

or

UNUSUAL

END

the the

and

at

the comple-

ATTENTION

signal

For

sent to the file control.

and

eight-bit mode.

and

their

two-digit operation code.

7631

as a programming

is

performed

Mnemonic

Code

DNOP DREL DEBM DSBM DSEK DVSR DWRF DVTN

DVCY DWRC DSAI DVTA DVHA

by

the

Numeric

Code

00 04 08 09 80 82 83 84

85 86 87 88 89

Release (DREL-04)

This order requires only The

order has meaning only for shared system operation. Whenever either system selects of the 7631, the release order

be

available for either system.

to

Eight-Bit Mode (DEBM-08)

it

remains in control of

is

This order requires only The

order conditions the

eight-bit mode. This mode of operation

the

when

using system format mode. Packed format numeric digits into one eight-bit character. data rate of the 70,

100 characters

file

per data characters for packed format, however, second with a maximum of 4,330 digits for a

the

two-digit operation code.

and

gains control

that

system until

issued, permitting the file control

the

two-digit operation code.

file

control to operate

is

operating in the packed

is

the packing of two

is

required

The

in

the

normal

control in the eight-bit mode is

second with a maximum of 2,165

data

track capacity; when using

data

rate

is

140, 200 digits

data

per

track

capacity.

Six-Bit Mode (DSBM-09)

This order requires The

order conditions six-bit mode. operating in the six-bit mode

The

the

two-digit operation code only.

the

file

control to operate in

data

rate for the file control when

is

90,100 characters

the

per second with a maximum track capacity of 2,800 characters.

Seek

(DSEK-80)

The

order for this operation causes the specified access mechanism of the addressed module to locate itself the

proper cylinder

When

the

order has

it

signals

END

and its own routine while disk storage executes operation. A seek may mechanisms on same

file

control. An

seek

is

given to

the

access mechanism

Upon completion of a seek operation,

signal

is

sent to the computer. ciated with the access mechanism to indicate this condition. This indication of

the

status

data

command.

The

access is serviced

and

to select the desired head.

been

received

by

the

file

control,

allows the computer to continue with

the

seek,

be

directed to other access

the

disk storage units attached to

UNUSUAL

an

access mechanism in motion or

is

inoperative.

END

signal results if a

an

In

addition, a

is

set in status

is

ATTENTION

bit

asso-

data

sent as

part

transmitted in response to a sense

attention indicator

by

either a prepare to verify order

is

reset when

the

or another seek order.

The

seek order, preceding a cylinder or full track

order,

is

not necessary when the current setting of the

at

if

10

access mechanism corresponds to the desired address. Also, a seek order single-record operations on

Prepare to Verify, Single

The

order for this operation conditions for a single-record type of operation the

following functions:

l.

Select

2.

Specify

3.

Prepare to transmit record

need

not

be

repeated for consecutive

the

same track.

Record

the

desired module

the

address to

in

response to a subsequent

be

data

and

verified.

from or to

(DVSR-82)

the

file control

and

to

access mechanism.

the

addressed

read

perform

or write

command.

The

order sent to

tion

with

the

specify the

unit anism is already located and

the

desired

operation,

the

file

control is

command. Access

to

be

selected. Since

and

head

is selected

held

and

in

by

remainder of the order

used

in

conjunc-

module

the

access mech-

the

track position

the

previous seek

is

used for verifi-

number

cation purposes only.

The

file control each record address as against

the

address furnished

(in

single-record

it

comes under

by

mode)

the

order until

compares

read

head

the

desired address is found.

Information can areas only as defined writing continues until either a the

computer or record, depending mand

is being executed.

Prepare to Write, Format (DWRF-83)

This order conditions

track for

of

the

order insignificant). two-position key-lock switch must position;

the

addresses of

order must precede

Prepare to Verify, Track with (DVTN-84)

This order, followed

mits

the

reading or writing of only particular track; all addresses are skipped over. address portion of this order must specify

be

read

from or written into record

by

format tracks. Reading or

STOP

signal is issued

the

file control recognizes

upon

whether a

the

file control to write a format

cylinder specified

(the

last two positions of this order are

To

address a format track,

by

read

the

be

track address must

the

cylinder. To write a format track, this

the

write command.

by a read

be

No

Addresses

or write command, per-

the

or write com-

address portion

the

in

the

one of the track

the

records on a

the

by

end

of

format

WRITE

The

home

address.

This order instructs

the

file control to

do

the

fol-

lowing:

l.

Select

the

2.

Supply

desired module

the

home address to

and

access mechanism.

be

verified.

3.

To receive or transmit only

sponse to a subsequent

Reading or writing begins

ing

the

home address,

and

records skipping over addresses until

signals

point. Non-verification of

an

STOP

UNUSUAL

or

the

file control recognizes

the

END

signal, with no transmission of

the

records

read

or write command.

at

the

first record follow-

continues through

the

computer

the

home address results

data

in

re-

the

index

in to

or from disk storage.

Prepare to Verify, Cylinder Operation

This

is

an optional feature.

(DVCY-85)

It

permits reading or

writing of data (skipping over addresses), beginning

at

the

first record after dressed track ord locations the

end

STOP.

This order is always followed

command.

and

the

of cylinder

The

following functions are performed in

the

home address of

the

ad-

continuing through successive rec-

tracks of the cylinder until either

is

reached

or

the

computer signals

by a read

or write

the cylinder operation mode:

l.

Select desired module

2.

Specify desired home address to

3.

Transmit

data

after

and

the

subsequent

access mechanism.

be

verified.

read

or write

command has been given.

Prepare to Write Check

This order

is

used with a write command to check any

(DWRC-86)

record, track, or cylinder of tracks of information.

This order performs a bit-for-bit comparison, comparing the information recorded on same information stored in core storage of puter.

If

data

agree, the order terminates

signal;

UNUSUAL

orders to write

if

data

END

disagree,

signal.

The

and

check recorded

the

order terminates

sequence of commands

the

data

disk with

the

with

an

with

is:

the

com-

END

an

and

Seek Prepare to Verify

(Single, Track, Cylinder)

xxxxxxxx*

Write Prepare to

Write

Check

xxxxxxxx*

Write *Must

It

be

same address

is

not necessary to follow a write command

with

a write check operation.

Set

Access

This file control order causes nect

(It permits

access mand

Inoperative

the

addressed access unit from

the

unit

from

(DSAI-87)

programmed disconnection of a faulty

the

system.) Any subsequent com-

to this access will result

the

file

control to discon-

the

in

an

UNUSUAL

file

control.

END.

Operations

11

Reactivation of the inoperative access unit

by

complished manually

the customer engineer after

is

ac-

the fault has been corrected.

Prepare to Verify, Track with Addresses

This order, followed

by

a read or write command,

(DVTA-88)

permits the reading or writing of a full track of information, including record addresses makes use of the home address

and

records.

that

defines the track

It

address.

This order instructs the file control to do the fol-

lowing.

1.

Select the desired module

2.

Supply the home address to be verified.

3.

Condition the track basis

and

file

control to operate on a full-

receive

and

access mechanism.

and

transmit both record addresses and record areas in response to a subsequent read or write command.

The

order

is

used whenever changes are to to record addresses be

made on a track

and

insertions, or deletions are to

that

contains randomly distributed

be

made

records.

The

execution of this order

by

formed in

that

the prepare to verify (cylinder operation)

only the home address tion is successful, reading or writing will begin following record address records signals

and

the record addresses until the computer

STOP

or

the

file

control recognizes the end of format area. Non-verification of sults in an data

Prepare to Verify, Home Address

UNUSUAL

to or from the disk storage.

This order prepares

END

signal with no transmission of

the an entire track of data home address identifier. supplied for subsequent verification. this order, the home address switch must

the

switch is located on

This operation

the

computer or when the

is

7631.)

terminated by a

is

similar to

is

verified.

and

continue through

the

home address re-

(DVHA-89)

file

control to

and

addresses including the

The

home address must

If

read

For

execution of

be

STOP

signal from

file

control recognizes the

that

per-

verifica-

at

the the

or write

be

on. (The

index point.

Sense

The

sense command instructs

mit

status data to the computer to indicate error

unusual conditions as well as attention conditions.

is

This operation that

only the ten 4-bit characters are transmitted to

similar to a read command except

the

file control to trans-

and

the computer. data

channel of the using system over the

and

1 bit lines. From the data channel, the 4-bit characters are converted to either the (7080

and

sent to the computer.

Status

and

control operation performed

and

are available to the computer sense command. by

the computer before the initiation of the next read,

7090) or

data

The

status data are transmitted to the

BCD

6-bit character

the

are set in

The

status

two-of-five code

bit

form for each read, write,

data

should

by

the

by

(7070/7074),

means of

be

BCD

A,

file

control

called for

4,

2,

the

write, or control command. (The initiation of the next command resets all error indications of the status

data. )

Figure 9 shows the make-up of the status data trans-

mitted to the data channel of the using system.

Status character 0 summarizes

condition. Characters 1

and

the

type of check or

2 give the type of check encountered. (Invalid address check has been added.) Character 3 gives the different, exceptional conditions; character 4 gives the data mode; characters 5, 6, 7 give attention conditions;

and

characters 8

and

are reserved.

-

Comment

Summary

Byte

Check

Data Check

Condition

Data Mode

Attention

Status Bit Char

0

1 3

2

3 3

4 3

5

6

7

8,9

Figure 9. Status

BCD

No.

Bit

3

A Reserved

4

5 6 2 7 1

5 4 Inval id Code Program 6 7 1 No Record Found 3 5 6 2 Data Compare 7

5 4 6

7 1 File Control

5 6 2 Reserved 7

3

5 4 Module 1 6 7 1

3

5 4

6

7 1

3 5 6 2

7

Program Data Check Exceptional Condition Invalid Sequence

A

Format Check

2

Inval id Address

A

~spoose

4

1 Parity or Check

Access

A

Access Disk Storage

2

Reserved

A

4 Six-Bit Mode

1 Reserved

Module 0

A

Module 2

2

Module 3 Module 4

A

Module 5 Module 6

2

Module 7 Module 8

A

Module 9

4

Reserved.

1 Reserved

Reserved

Data

Assignment

Check

Check-

Inoperative Note

Bit Assignment

--

-

Check

Char

Code Check

Ready Exceptional

Circuit

Check

Circuit

Check

9

12

Write

A write command pare

to write check, prepare ceded UNUSUAL the between

Write Format Track Operation

To

to verify order. A write command, not pre-

by

one of these orders, is

END

file control.

the

write a format track, three conditions must

1.

The

format switch must

if

not, no writing of

place.

2. A prepare dress of one of be

received

control.

3.

The

prepare lowed storage location characters

During a format write operation, legally accept only four characters: and

BCD

4. are used to write bits;

BCD

2' s are used seven zero bits. each 6-bit character; for a space tion in

bit

the

8-bit mode, cial character of nine one bits; the

special character of nine zero bits. Nine tions are required for each 8-bit character; position is required for a space

characters.

A typical core storage layout for

the

6-bit

mode

10.

When

organizing a the information vided for; however,

must

always

prepare

be

preceded

to write format, or a

terminated

signal with no transmission of

(A

no operation order

prepare

to

...

and

be

the

format track will take

to write format order

the

tracks of

and

normally terminated

to write format

by

a write command specifying a core

that

contains

that

are used to write a format track.

can

the

write command.)

in

the

WRITE

with

the

order

the

field of special

the

BCD

1, BCD

For

operation in

the

special character of seven one

to

Seven

the

6-bit mode,

write the special character of

bit

positions

extra

are

bit

position is required

used to separate characters.

BCD

3's are used to write

BCD

4's

are

bit

used to separate

n records in

and

the

8-bit mode is shown

data

track in core storage, only

that

is to

be

recorded

when

organizing a format track

by

a pre-

with

an

data

to

be

inserted

be

met:

position;

a track ad-

cylinder must

by

the

file

must

be

fol-

7631 will

2,

BCD

3,

BCD

l's

required

For

opera-

the

for

spe-

used to write

bit

posi-

the

extra

bit

both

in

Figure

must

be

pro-

in core storage,

the

special

BCD

characters

must

be

provided to write every character position. This in-

the

HAl

eludes

and

gap areas

areas for

When

the

laying

siderations must

area, as well as all

that

are to

associated

out

a format track,

be

given:

Format Track Capacity:

positions available

when

be

used

data

tracks.

The

writing a format track is:

other

addresses

to

define

the

following con-

maximum character

Six-Bit Mode: 2,869 character positions Eight-Bit Mode: 2,234 character positions

the

total

data

These figures represent

track capacity

(2,840 character positions for 6-bit; 2,205 character positions for 8-bit) plus tions) plus 11

character positions (space only, user does

the

HA2

vide characters for this area),

at

the

end

of

for written

by

the

7631 File Control. Exceeding

HAl

area (24 character posi-

gap

(16 character positions), minus

that

must

be

track

that

are to

be

automatically

not

pro-

provided

the

track

capacity results in a format check.

Track Identification: This area immediately follows

the

index point

recorded

Gap

BCD

data

1 must contain three

3's;

Gap 2 must

3's

and a BCD

always written

and

corresponds to

track area

contain a

4.

The

in

the

8-bit mode

the

and

consists of three parts:

BCD

4's;

HAl

must contain nine

BCD

4 followed

track identification

and

will

be

HAl

the

pre-

by

area

same

ten

for all format track layouts.

Home Address

four more characters assigned for tions are

needed

Two

BCD

1's (6-bit mode)

for

(HA2): This area

than

HA2.

The

four character posi-

each

record

and

the

each

must

number

contain

address

area to provide space for internal synchronization in-

formation.

home address identifier, then, six in this area. must

X dress BCD

4's,

Record Address (RA): This area

more

For

be

used

instead of

Gap: An X

(RA).

This

depending

BCD

1's

than

example, if

operation in

the

gap

must

gap

is

made

upon

the

number

HA2

is

BCD

the

BCD

1's.

precede

up

of 12

a two

1's

8-bit mode,

every record ad-

character

must

BCD

mode of operation.

must

contain four

of characters aSSigned

2's

be

BCD

used

or

3's

12

is

of

Track Identification

HAl

iGap

I

of

or

BCD

4)

I 444

444

3

Format

333333333 333333333

Track Layout

6-Bit a-Bit

Number Characters

(1,2,3,

Figure 10.

Gap

43333333333~

9

12

2

HA2 X Gap

111111 222222222222 1111111111 211111111112

333333 444444444444

6 Min 12

RAI

333333333::1

10

Min

Y

Gap

433333333334

12

Record 1

111----111

333----333

6 Min

X

Gap

[RAN

222222222222 1111111111 211111111112

444444444444

12

It3333333

10

Min

YGap

433333333334

12

Gap

Record N 3

111----111

333----33J

6 Min 1

Operations 13

2

4

for RA.

BCD 1's

mode, must track as

made

BCD 2 for

mode, 10 BCD 3's

there of operation. 84 3's must character

the either

For

example, if

must

be

BCD 3' s

be

as

many

there

are

Y Gap: A Y

up

of one BCD

the

6-bit

the Y gap

and

Record Areas:

are

characters in

For

BCD 1's

are

must

to

be

contain

used

at

record plus

Gap 3:

Gap

last record

a BCD 2

RA

contains

used.

For

operation

must

be

used

instead of BCD record address areas on records.

gap

must

follow every

2,

followed

mode

of operation.

is

made

up

of

one BCD 4 followed

another

There

BCD

4.

must

the

record, for

be

four more BCD 1's

example, for an 80

be

provided.

instead

of

For

the

least six characters,

the

four extra BCD characters.

3 is a

or

area

a BCD

one

on

the

4,

character

track. This

depending

of operation.

Format tracks can be written

or

tion

excepting ways

Write Home Address Operation

The the

prepare

issued to

immediately follow.

the other, never,

the

track

identification area, which is al-

written

in

the

8-bit mode.

conditions necessary for this operation

home address switch on

to verify

the

(home

file control,

The physical address portion of particular the must track. mum extended to tem.

for

the

ones

characters of non-significant

track

beginning

be

the

The

home address identifier

of

two

match

The

number

HA

identifier is

that

were

and

begins

of

the

HA2

home

address identifier of

characters.

the

word

of characters

determined

previously

the

HA

identifier

and

will

for

as

a mixture

the address) and

that

file control compares

the

home

the

area.

If

desired, this area

length

requested

written

after

not

be a part

compare.

This operation continues

ing

the

gap

between

dress.

On

detection of

writes

the

three-digit check character.

the

HA2

the

with

gap,

the

and

continues writing record addresses end

of

the

track.

If

a stop signal occurs before sensing

track,

data

transmission stops,

tinues writing blanks to

the

but

end

of

ten

digits,

then

in

the

eight-bit

1.

the

RA.

This

by

10 BCD 1's

For

the

6-bit

character

the

8-bit mode, BCD

BCD 1's. This

that

is, a two

gap

that

follows

character

upon

the

one mode

of

both modes,

are

7631

be

on,

operation

the

write

order

command

address on

write operation

The

first characters

the

particular

must

be

a mini-

may

of

the

using sys-

by

the

by

the

number

on

the

format. All

the

second of

address

file control detect-

the

first record ad-

the

file control

The

operation

and

records to

the

file control con-

the

track.

14

There

format

gap

is

and

a

8-bit

by

than

mode

record,

area

is

mode

opera-

that

a

be

the the

at

be

7631

of

are

then

the

end

of

Write

Track

with

Addresses Operation

Conditions necessary for this operation to verify write

(track) for a home address bit the address fails to compare, mediate a no record found bit. compare dress trol continues filling the dresses. acters to last check will ditions results. a record, writes blanks to

(track

command.

order,

against

prepare

with

addresses) order, followed

the

Under

the

address

control of

file control searches

and

compares this address

that

to verify (track) command.

the

UNUSUAL

END

and

Upon

the

file control will transfer

and

proceed

in

the

usual manner.

the

record

computer. This includes

The

file control also supplies

be

issued to

have

If

written

character

the

data

at

the

area

the

computer

been

detected. Otherwise,

computer

signals

transmission stops,

end

of record area,

was previously issued

file control issues

indicates in its status

a successful home address

area

both

end

of

each

is reached, a

providing no error con-

STOP

the

prepare

the

with

records

the area.

in

but

then

are a prepare

to verify

data

bit

If

the

an

record ad-

The

file con-

data

and

check char-

When

NORMAL

UNUSUAL

the

middle

file control

writes

check characters.

Write Single Record Operation

Conditions necessary for this operation pare

to verify (single record operation)

sued

to

the

low.

The control Upon

finding a reads off pares

it

plied

to

record).

file control

record address

by

sensing

the

address

bit

by

bit

the

adapter

If

the

address does

the

record

contained

with

during

and

that a write

area

is recognized in

end

of a long

address area,

the

address previously sup-

prepare

not

compare,

in

are

that

a pre-

order

be

command

the

gap

in

the

format.

the

file control

the

area

and

to verify (single

the

file control continues searching succeeding address areas comparing control passes paring found puter compare write pared file control· automatically transmits

characters following defined

If

ord

area ord, is reached. After a

NORMAL

check has occurred, in

the

status

without

true,

over

the

address.

by

the

address the

address,

bit

and

transmission of data.

the

record immediately following

Data

format track.

contained

index

point

it

will register

issue

an

file control will cause

are

furnished

the

end

a stop signal is received

the

file control will continue to

with

blanks until

END

is issued to

the

end

the

check characters

which

in each.

twice

the

UNUSUAL

END

Upon

by

the

of

the

record

at a midpoint

of

the

formatted

the

system unless a

case

UNUSUAL

If

the

without

no-record-

to

the

an

address

the

1301 to

the

system.

code check

area

in

the

write

the

are

recorded,

END

would

result.

by

track

for

with

home

im-

word

from

ad-

the

END

of

the

is-

fol-

file

com-

and

file

com-

The

as

recrec-

area

data

a

14

Write Track With

The

conditions necessary for this operation

a

prepare followed with order from the

by

the

prepare

is

compared

the

1301.

no-record-found is issued to the

file control skips

record

area continues skipping addresses until

the

index

sued

to

the

cur

during

the

operation will

record in which

END

issued.

If

computer

data

transmission stops,

writing blanks to

No

Addresses

to verify (track

without

a write command.

to verify (track

with

the

If

the

home

bit

is registered

the

system.

and

point

the

writes

is

If

the

first address area into

the

sensed. A

system, providing no

data

transfer.

the

In

be

terminated

error

the

was

signals stop in

but

end

of record area,

The

home

address fails

address compares true,

record.

and

event

detected

the

file control continues

check characters.

Read or Write Cylinder Operation

Operation of

the

by

having (cylinder operation) dress issued track address is read

On

begins

being

ignored

dresses operation. last record of sends a writing is one address By indexing the cylinder of information has signal is head

If

ord, trol continues to pares check characters; writes blanks to

in

the

cylinder

7631. A cylinder the

computer

with

the

on which

the

compared

or write

is

received.

a compare equal,

with

all of

read

or

written

in

the

same

the

track has

new

head

continues.

higher

one

head

7631 continues

generated

of

the

cylinder has

the

computer

data

transmission stops;

read

end

mode

is

mode

read

send a prepare

order

to

the

order

is

the

operation is to start.

bit

by

bit

in

the

data

the

records

and

manner

Rather

on

with

the

as a track-without-ad-

than

causing

been

address to

The

than

address on

reading

head

the

address

the

writing

each

been

in

the

7631

when

been

operated

signals

STOP

in

but,

to

end

of record,

if

writing,

of record,

then

characters.

No

wrap-around

feature

is

included

operation to cause operation to

are

that

addresses)

order

be

address received

without

addresses)

address transmitted

to

compare,

and

UNUSUAL

END

the

The

file control

writing

NORMAL

error

the

records

END

is is-

conditions oc-

of a parity error,

at

the

end

of

the

and

UNUSUAL

middle

an

of a record,

then

writes

optional feature

or write is set

the

up

to verify

file control.

home address of

the

7631

The

after

adthe

home

the

transfer operation

the

addressed

record

END

processed,

1301

and

sent

head

addresses

when

the

reading

to

the

address.

track

the

7631

1301

disk revolution, until

the

entire

processed.

the

The

highest

END

order

on.

the

middle

if

reading,

the

writes

of a rec-

file

and

then

file control

the

con-

com-

check

in cylinder

begin

again

at

the

low-order pleted

Write Check Operation

Each check operation gram sequence

Prepare Write Prepare Write

The dressed record, the acters generated record. true check will set

head

after

the

high-order

its reading

of

the

control.

of orders

or

writing.

write operations has a companion write

which

The

is optional

operation requires

and

commands:

to Verify . . . XXXXXXXX

to

Write

Check

7631 will compare

bit

system,

that

The

at

will

and

end

the

be

recorded

of this

write operation. A

the

data

the

by bit,

same

time

compared

on

operation

compare

data

recorded

with

the

generating check char-

with

the

track, following

is

error

check

head

and

the

-------XXXXXXXX

--------

write

those previously

the

during

bit

data.

During

the

checked to determine

a write check operation

format

gap

detector

if

circuits in

they

are

on a format

the

within

their tolerance. A file control circuit check is circuits do

On

comparing

end

END

signal.

not

meet

reception of a

data

of

the

present

specifications.

STOP

signal

already received,

record

area

and

the

7631 continues

then

issues a

Read

Read Home Address Operation

This operation requires

address) is sent to

or

follows. write

The

home

read

address. this operation is to recover tracks of information in a file

dump

operation. This

on

the

format track for recognition of dress areas. a

proper

the

beginning of

puter

With

gap is

can

restore a file major mechanical change. physical address portion of begins reading

address

and

with

record

termination of this operation occurs

senses

the

index point.

UNUSUAL

data

END

check.

is issued,

The

that a prepare

the

7631

and

(home address)

The

most useful application of

operation

this

operation

provided

the

between

home

address area,

to

normal operation

The

the

home

data

of

the

At

that

depending

computer

may

to verify (home

that a read

is

analogous to

does

and

assuming

index

7631 compares

home address

address identifier. All

track

are

when

time

either

on

the

terminate

has com-

under

pro-

following

in

the

ad-

data

from

the

same as a

a write

in

the

status

track

7631

are

specified

noted

if

the

continues till

NORMAL

command

the

not

depend

data

and

ad-

that

point

and

the

com-

after

the

and

read.

The

the

7631

NORMAL

state of

the

or

the

opera-

a

Operations 15

tion earlier the

7631 will terminate nally complete reading of operating particular record, the 7631 will send either or

UNUSUAL

Read Track

Conditions necessary for this operation are pare

to verify (track) order lowed operation companied the

recorded home address on

failure to compare will cause "no record found" to

set

in

by

at

the

END,

with

by a read

by

comparing the home address which ac-

the

status data

issuing a

time of

depending on

Addresses Operation

command.

STOP.

Upon receipt of

data

transmission

the

record on which

the

STOP.

the

state of

be

issued to

The

file

and

it

At

the

end

of

NORMAL

data

check.

that

a pre-

the

7631, fol-

control begins

STOP,

inter-

was

the

prepare to verify (track) order against

the

selected track. A

be

and

causes

UNUSUAL

END

to

be issued to the system. A successful compare permits the

7631 to begin reading

The

area. sent to the minates

comparing a track. At

record address is

the

system, followed

next address

when

the

that

and

7631 senses

check characters of

time a

is issued, depending upon

STOP

signal prior to

will cause

signal a it

is

operating

Read Single Record Operation

the

NORMAL

7631 to stop

END

at

the time of the

This operation requires

to

verify (single record) order

with write (single record) operation,

at

read

record, etc.

NORMAL

the

logical

at

the

end

the

the first record address

out

by

the

that

END

state of

end

data

The

in its entirety

record

operation ter-

it

has completed

the

last record of

or

UNUSUAL

data

of this operation

transmission

and

then

END

check. A

and

of the record on which

STOP

signal.

completion of a prepare

and

read

command.

the

read

As

(single record) operation has no predetermined starting point on

the

disk,

that

is,

when the instruction is received

by

the

7631,

it

immediately begins searching for a

record address.

Upon finding one,

the

7631 does a bit-by-bit comparison. A failure to compare causes the control to continue searching on the next record address. passes

ular record. the address to

The following or the logical stop

the

Read Track

This operation requires

and a read

"No record found" the

index point twice in its search for a partic-

Upon obtaining

7631 causes

be

the

read

7631 verifies

the

end

UNUSUAL

data

end

END

at

end

of this operation will cause

transmission

of

the

record.

with

No

command,

is

registered

an

address compare true

if

record immediately following

and

the

data

to

be

the

legality of

of the record

that

time. A

the

and

STOP

sent to

sends

the

check characters

the

signal prior to

the

and

to signal a

Addresses

that

a prepare to verify (track)

in

that

sequence,

NORMAL

be

the

7631

that

system.

NORMAL

7631 to

END

executed.

The

7631 waits for ginning to compare prepare

to

verify order against address. A compare failure causes "no record found" in

the

home address area before be-

the

address supplied

the

recorded home

the

7631 to register

the

status word.

If

compares successfully, the 7631 carries out track operation dress

and

tinues with addresses ignored

record

data ends when At

that

time

EARLY

END

In

that

case,

is operating

the

case may be.

by

skipping over

reading

the

first record.

being sent to

the

7631 finishes the last record of

the

appropriate

the

first record ad-

The

by

the

7631

system.

END

signal is issued. An

may occur because of a system

the

7631 finishes

and

issues a

the

NORMAL

record on which it or

UNUSUAL

operation con-

The

Checking

The

7631 File Control checks for twelve individual

error conditions possible in

The

age. an

Parity or Character Check

The

sensing of

UNUSUAL

7631 is

END

an transferred from is checked.

bit

as well as

into

the

The

If

status data.

character code check is

anyone

signal to

odd-parity machine.

the

an

even

the

summary

three check characters for each address

as bits are

read

from the disk surface during a

operation. These newly generated characters are then

compared

and

bit

recorded,

by

bit

in

the gap following each address

each record during

compare will indicate

Invalid

If

address,

Address Check

a seek operation

the

access mechanism

customer engineer track

engineering

use).

If

command is given, and

an

at

Response Check

The received

immediate

response check indicates

by

UNUSUAL

the

7631 within sponse check can only occur as a result of a write operation.

the

operation of disk stor-

of these conditions causes

be

sent to

computer,

number

data

the

computer.

As

characters are

the

bit

count of each

is

detected, this check

check bit, will

made

by

with those previously generated

the

write operation. Failure to

the

occurrence of

is

attempted using

may

(a

data this happens, an

invalid address check occurs

END

signal results.

that

the

an

be

track for customer

and a read

a character was not

allotted time. Re-

with

the

address

the

read-

and

only operation the

track.

STOP

signal.

END

as

be

set

generating

and

record,

read

and

error.

an

invalid

moved to a

or write

read

or

16

Data Compare Check

Data

compare check check operation. pare

error was check. from

During a write

the

disk surface

those transferred from

Format Check

The

format check occurs a write check either

an

or four)

illegal

or

because

of a fonnat

file control prior

No

Record Found

The

"no record found" indication occurs if trol fails to locate on a

prepare

to verify order.

can

occur only

The

condition indicates

detected

somewhere check operation, and

compared

the

computer.

during

track.

code

(any

but

STOP

signal was

to

sensing

the

track address

either

The

during

bit

fonnat

that

during

data

by

cause

a write

a com-

write

are

read

bit

with

write or may

be

a BCD one, two, three,

not

sent to

the

index point.

the

file con-

that

was issued it

File Control Circuit Cbeck

This check occurs

due

to malfunctioning

of detection circuit, address comparison circuit, check character code generator in

Shared System

The

7631 different random access storage. have

Figure 11. Shared System Three-Way Switch

Data

a three-way switch as shown in

Operation

File

Control, Models 3

Processing Systems to share a common

The

the

file control.

and

4,

permit

7631, Models 3

Figure

the

and

11.

or

gap

the

two

4,

Invalid Sequence

The

invalid sequence condition write operations in when

a write

trol

without a preceding

pare

to

verify

two

command

or

prepare

ways.

is

received

and

to

write

can

In

one case,

by

properly executed pre-

format

second case, invalid sequence occurs

check

order

is

verify order,

preceded

prepare

by

other

to write format order, erly executed write command. prepare cede a read

Invalid

The trol is given

Access

This indication occurs fails to mechanically

Access

The dressed access

Disk Storage Circuit Check

to verify

is

the

only legal order

command.

Code

invalid code indication occurs

an

order

that

cannot

Inoperative

respond

Not

access

to a seek order.

out

of order

Ready

not

ready

indication shows

is

in motion from some

when

or

the

may

than a prepare

When

when

be

performed.

access mechanism

The

not

prior

This check indicates a circuit failure in Storage.

occur during

it

occurs

the

file con-

order.

In

when a write

and

prop-

reading, a

that

can

pre-

the

file con-

access

may

exist.

that

the

seek order.

the

1301 Disk

the

to

be

ad-

When shown), if a 1410) to

Control is retained until a release order, restoring neutral. Assume

l.

storage instruction,

the

If

System B

switch

first system

the

is

in

the

neutral

to

issue

an

file control gains control of

the

controlling system issues

the

three-way switch to

that

System A has control of

is

a 1410

the

and

1410 will receive a

order

tries

position ( as

(instruction,

the

to

issue a disk

indication.

2.

If

System B

age order, a channel

3.

If

System B

storage order,

struction

nel will

4.

(TRS

wait

If

System B

disk storage order,

7631

is

available.

Two

7000

Series Systems Sharing a 7631 File Control

At

the

completion of any seek operation, signal (seek systems will, in time, respond to

signal.

Depending system (assume system

is

a 7090

~md

interrupt

is

a 7080

but

does

not

01) before issuing

until

the

7631 is available.

is

a 7070

complete)

on a

or

the

channel will

is

sent to

number A)

responds first

tries

to

issue a disk stor-

will result.

and

tries to issue a disk

use a transfer

the

order,

7074

and

both

the

ready

the

tries to issue a

wait

until

an

attention

systems. Both

seek complete

of timing factors, one

and

issues a

sense command. This. command gains control of

7631 as previously described. able sense data, system A determines

the seek complete signal. the seek order

the

signal, system A releases

tem B

to

is

serviced.

respond to

the

On

examination of avail-

whether

If

system A caused

If

system A

the

7631

attention signal

did

and

it

caused

the

signal,

not

allows sys-

service

the seek order.

763l.

7631:

busy

in-

chan-

the

cause

Operations 17

IBM

1410

and

7000

Series

Systems

Control

File

At completion of any seek operation, nal is sent to

both

using systems

Sharing a 7631

an

attention sig-

with

the

restrictions:

1. A prevent

4 XXXXX

Processing Unit,

from reaching

(allowing seek complete signals

the

1410 issues a seek command.

2.

Reception of a seek complete

further conditioned

7631

is

disconnected from

to

the

1410, seek complete signals

If

the

7631 complete signals system releases

Subject 7000 shared disk storage system as described for tems, except for whether which

an

the series of Y ( I ) d tests to determine interrupt. Having found by

a seek complete,

seek complete instruction

W)

is

used to

the

turn

on a latch in

which

blocks seek complete signals

1410 system. This latch is

to

be

by

previous use of the 7631.

both

systems or

are

is

connected

are

the

to

these restrictions, operation of

the

interrupt

1410 initiated. This

to

the

7000 series system, seek

not

sent

to

the

1410 until

7631.

is

essentially

7000/7000 shared disk storage sys-

the

1410 method of determining

was caused

by

method

the

that

the

interrupt

each

access mechanism

(M/L

the

serviced)

by

the

is

sent to

a seek command

consists of a

nature

was caused

seeking because of a 1410 command must tested

by

issuing

tion

to

set status indicators for

and

then

an R (1)$

Programming Shared Disk Storage

In

programming a

two

methods

1.

System A issues one tains control of mand)

tems times

until all seek commands have

2.

Two

or more seeks issued

may

be

may

an

may

the

input-output

to

test

shared

be

used:

or

7631

(by

no-operation instruc-

the

access mechanism

for a busy condition.

disk storage system, one of

more seek orders not

issuing a release com-

been

completed.

by

either or

in simultaneous operation. Seek execution

thus

be

eHectively overlapped. Operation

as follows:

a. System A issues one or more seek commands

and

then

a release.

b. System B issues one

and

then

a release.

c.

Control of

nected from

point

the

both

depends

or

more seek commands

7631 is now logically discon-

systems. Operation from this

on

which systems are sharing

following

X F

IBM

1411

turned

oH

when

1410 is

If

the

connected

the

1410.

the

7000

the

1410/

the

same

of

the

that

is

then

be

and

re-

both

sys-

is

the

7631.

If

one of

the

systems

is

a 1410, priority processing feature, which allows interrupts

to

be

processed

by

the

system,

must

available.

Instruction Times

Ten

digit orders

mode

and

190 microseconds in 8-bit mode. Two-digit

orders

demand microseconds quires 123 microseconds in 6-bit seconds vary record

in

in time duration

(for

require

55 microseconds in 6-bit

in

8-bit mode. A sense command re-

8-bit mode.

single record operations)

148 microseconds

mode

Read

and

write commands

depending

on

mode

and

the

and

in

and

158 micro-

length of rotational

coincidence of starting points. A cylinder operation in-

volving all 40 tracks within a cylinder will take

1.5 seconds.

Access time to position access mechanism is 50 to

180 milliseconds

and

average rotational delay

milliseconds.

Access

The cylinder to another.

far

limits. To calculate consider five areas of 50 cylinders area access motion time for

section of

section to another section of

( one area

For

Motion

Time

access mechanism requires time to move from one

The

time

the

arm

moves within certain machine-defined

how

the

250 cylinders of a module organized into

of cylinders is

further

anyone

1.

50 milliseconds, to move

anyone

2.

120 milliseconds,

3.

180 milliseconds, to move

to

another area (crossing

example, to move

area.

to

move

the

required

much

per

area

divided into six sections,

the

an

access arm from track 0000

depends on

time will

(Figure

be

required,

12).

If

access is:

access arm within a

access arm from one

area.

the

access arm from

an

area

boundary).

to 1960 requires 120 milliseconds of access motion time.

To

move

the

access arm from track 1960

to

requires 180 milliseconds.

Access time from one track

mined

by

the

use of

Figure tion of two lines on a coded area of drawn drawn

horizontally from a

vertically from a

to

another can

13.

The

point of intersec-

FROM

track address

TO

address, indicates access

the

figure, one

be

and

time in milliseconds.

the

be

6-bit

75

about

is

17

how

each

2000

deter-

one

18

Area Cylinder

A B

C

D

E

0-

50 100 -149

150 -199

200 - 249

Cylinder Areas

49

99

0---9

I Sect 1 1 Sect 2 1 Sect 3 Sect 4 Sect 5 Sect 6

Figure 12. Access Motion Areas

10--1920-24

Sections within

1

aCyl

25--34

inder Area

and

35--

1

Sections

44145-49

(In Milliseconds)

TO

Track

Address

0-

~

M

o

0

,

8

~~8

0

00

0

§o-

~~

__

,

I

___

0-

,

'I

0 0

~

0- 0- 0- 0-

0-

0- 0- 0- 0-

~

~~M~

N M

,

, ,

,

I

8

888

8

"<too

NNMM

N

0- 00-

~

0-

"<t

, ,

0

00

~~

,.'?

'?

~8N

It') It')

0-

~

'?

0 0

-0

It')

~~~~

,.

~8°8

0000-0399 0400-0799

0800-0999

1000-1199

1200-1599

1600-1999 2000-2399 2400-2799

2800-2999 3000-3199 3200-3599

3600-3999

III III

Q)

4000-4399

-6

"'tJ

4400-4799

«

4800-4999

~

u

5000-5199

c

5200-5599

.=

5600-5999 6000-6399

g/

6400-6799 6800-6999

7000-7199 7200-7599

7600-7999 8000-8399 8400-8799

8800-8999 9000-9199

9200-9599 9600-9999

NOTE: • = 50 milliseconds

1

0-

00-

~

"

-0

"?

I

0

0000

8

~~8~

-0

0-0-

0-~ 0-0-0-0-

0-0-

0-

0-_

It')

, , I

-0"

"

-0"

"

~

00 00

, , ,

0

000

0

8

~

00

0- 0-

~~~~

000-

0-

, ,

, I

8 8

8

~~

N

00

000-

0-

000-

-0

0-

Figure 13. 1301 Disk Storage Access

~

""

120 milliseconds

1;1

= 180 milliseconds

Time

Operations 19

Control Panel

The control panel of the

for maintenance simulation purposes.

mounted on

an

has

the

right front cover.

exposed section

only for customer engineering usage.

7631

is primarily intended

The

control panel

and

a hidden section, intended

On

the

panel

exposed segment there are 122 indicator lights which reHect the status of ator switches are available sembly above panel. covered

data, commands

data

and

controls within the 7631. Oper-

in

a light

the

indicator section of

The

customer engineer section of the panel

and

contains

35

switches for simulation of

and

responses from the channel,

and

switch as-

the

control

and

responses from the files.

Power-On Switches

Power-On Key supplies DC voltages to the

the 1301's and

and

blowers.

AC

When

and

Lights

7631

and

voltages to the disk storage motors

the

switch

is

pressed, power

is

sup-

plied to the first disk storage for a power-on sequence.

the

When

on sequencing, a signal the power-on sequence,

Power-On Light, when on, indicates

supplied to the

first disk storage has completed its power-

is

7631

and

the 1301's.

sent to

so

on.

the

next one to start

that

power

Power-Off Key removes DC

from the

is

sequence for the

7631

and

1301's.

the 1301's

and

AC

operating voltages

and

initiates a power-off

DC-Off Key removes DC operating voltages from the

7631

and

the

1301's.

DC-On Light, when on, indicates

voltages are present on the

HAO Switch: This switch must

of, a home address operation.

is

execution

Write Inhibit Switch and Light:

toggle switch allows

7631

the

CE or diagnostic programmer

that

and

be

The

the 1301's.

on

to perform a write sequence of operations without the actual writing, thus not disturbing data.

The

associated light indicates this write inhibit

the

condition present.

Thermal Light: This light

if the temperature in

is

the light

on, the power-on switch of the 7631 is

effective. Power

the

is

down until the temperature returns

is

energized in the 7631

gates exceeds 1150 F. While

to specified limits.

Fuse Light:

or tripped cricuit breaker

Test Mode Light:

is

When the

this light

attached 1301's are not available for normal cus-

The

fuse light indicates a blown fuse

in

the 7631.

For

customer engineering use.

is

on,

it

indicates

that

the

tomer use.

DC operating

for logical

write inhibit

customer's

not

7631

and

20

The

following procedures form recovery routines for

IBM

Programming Systems packages. utilization of procedures

used

data

processing systems,

is

recommended

in

the

basis of

input-output

the

in writing

the

error

programming

For

efficient

use of these

input-output

routines.

Figure can occur minimum action required. examined

14

shows

the

with

7000 series systems

and

handled

7631-1301 error conditions

and

specifies

Data

check errors should

that

the

be

before program check or excep-

tional condition errors.

The

actions referred to in

Figure

14 are:

Action 1

1.

Repeat

to verify

and

the

operation once

read

or write.

(for

When

example,

prepare

a response check occurs on a read, or a response check or a format check occurs on a verify

is

not

write

required

or write check,

except on

the

IBM

prepare

7090-94

to

System.

2.

If

the

error condition persists,

(see

below).

Action 2

1.

Execute

2.

After a fifth

part

cess mechanism

1 of action 1 as

error

indication, recalibrate

with

a seek to

print

message 1

many

as four times.

the

outer customer

the

ac-

Error Recovery Procedures

engineering track. Use 9@00 seek address.

For

the

ify two

RDWC

-40

the

first order

the

second

The

two

First

Second word:

In

two

7070-7074,

alpha

order

2-5 6-9,

order

alpha

word:

digit representation

the

control

words for

where

word

2-5 contains

and

6-9 contains

word. order

words are as follows:

a:

800x9 x = 0-9

a:

@xxOO

as follows:

a: 9890909x99

3.

Seek to any

a:

469x9x9090

track

address. This moves

mechanism to cylinder zero.

4.

Seek to

5.

Execute

6.

After a

NOTE:

condition causes

lOCS

routine

In

the

desired track.

part

1 of action 1 as

ninth

error indication,

IBM

1301 IOCS routines, a no-record-found

an

exit

to

with

the

same record address causes ex-

ecution of a no-record-found error routine.

may have an overflow indication rogated on

the

track

that

caused

indication.

to

command

the

seek.

xx=00-39

the

order

many

the

user. A

that

the

9@39 for

For

the

( module

words

as four times.

print

message

return

must

no-record-found

the

must

spec-

example,

address of

number)

appear

the

access

1.

to

the

The

user

be

inter-

Sense Bit Assignment

Status Bit Char.

0 3

1

2 3 A

3 3

Figure

BCD

No.

Bit

A 4 Program

5

6 2

7 1

A

3

4

5

6 2 Format

7 1

4 Response

5

2

6 7 1

A 4

5

2

6 7 1

14.

Error

Conditions

Assignment Comment

Reserved Summary Byte

Check

Data

Check

Exceptional

Invalid Invalid

No

Invalid

Data Parity

Access Access 1301 7631

Condition

Sequence

Code

Check

Record Found Program

Address Program

Check

Compare

Check

or

Check

Char

Inoperative Not

Ready

Circuit

Check

Circuit

Check

and

Actions

Code

Check

Required

Program

Check

Program

Check

Program

Check Check

Check

Data

Check

Data

Check

Data

Check

Exceptional Exceptional

Exceptional

Condition Condition Condition Condition

When

During A

Operation

Read

Action Not

applicable

Not

applicable

Action

Action Action Not

applicable

Action

Action Action Action Action

Encountered

1

2

4

1

3

1 1

1

When

Encountered

During a Write or

Write

Check

Operation

Action

1

Not

applicable

Action

1

Action

2

Action

4

Action

1

Action

3

Action

3

Action

1

Action

1

Action

1

Action

1

Error Recovery Procedures

When

Encountered

During a Control

Operation

Not

applicable

Action

1

Not

applicable

Not

applicable

Not

appl

icable

Not

applicable

Not

applicable

Action

1

Action

1

Action

1

Action

1

Not

applicable

21

Action 3

l.

Execute

Exception:

sequence

prepare

and

write check.

2.

After a fifth

Action 4

l.

Seek

moves

neering

2.

Seek to

read

or write.

3.

If

Message 1 Format

Message 1 identifies

procedure

part

1 of action 1 as

In

the

case of a write check,

should

to

the

track

the

be

repeated,

verify,

to

subsequent

error

any

track

indication,

access mechanism from

to

cylinder zero.

the

desired track.

error

condition persists,

an

is

determined

many

as four times.

the

original

not

part

1 of action 1:

write,

prepare

print

to

verify,

message

address ( 0000-9999). This

the

customer engi·

Prepare

uncorrectable error. by

the

application.

print

to verify

message

Further

Minimum: 1-4, inclusive Recommended, if core storage permits: 1-8 inclusive Maximum:

l.

associated

2.

1-10

xxxx: a message

with a halt

Type

of Error: read, write, write check, or control.

code

used

when

or waiting loop.

the

message is

1.

and

l.

3.

Unit

Involved: access number, module

track

number.

4.

File

Control Status

examination of

byte

Word:

bytes 0-4 inclusive;

0 will reveal any multiple

conditions.

5.

Channel

word for

6.

File Control Status

7.

Nature

8.

Preceding

9.

Previous number, dress

sought

10.

Current number, which reached,

Statistical Print-out

At

the

end

designation

the

channel

of

Data:

and

at

the

Word:

packed

final status or control

time of

bytes 5-9 inclusive.

or

unpacked.

control orders.

Unit

Involved: access

track

number;

on

the

Unit

track

number;

the

access mechanism was going,

at

error

of a

program

FROM

address,

module

in

error.

Involved: access number,

TO

address,

time.

segment or run, or

the

error.

number,

the

venient time interval, a Message 2 should

Message 2 Format

l.

Access

2.

Number

3.

Number

number,

module

number.

of entries into error routine.

of Message 1's

printed

(uncorrectable

errors) .

number,

error

module

address to

or

at

a con-

be

printed.

an

ad-

had

22

11/62:7.5M-FW-28