Singer 40 Reference Manual

REFERENCE

MANUAL

MODELS

40

AND

42

DISC

Re-order No. INT

DRIVES

Publication No. 40-298

January 1972

10-211

R1

Copyright © 1972, The Singer Company
All

rights reserved throughout

the

world.

SINGER

BUSINESS

MACHINES

LIST

OF

EFFECTIVE

PAGES

Page

i

thru

0-1

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

5-1
6-1

7-1
8-1

9-1

iv

thru
thru
thru

thru
thru

1-3
2-2
3-2

7-3
8-4

Effective Date

1/72
1/72
1/72
1/72
1/72
1/72
1/72
1/72
1/72
1/72
1/72.

1/72

Models

40 and 42

Reference

Manual

i

CONTENTS

Page

INTRODUCTION

1

GENERAL

OPERATOR

2

3

INSTRUCTION

Read

Six-Character

4

WroTE

READ OPERATIONS

5

MULTI-PARTITION

6

TIMING

7

OPERATING

8

CONDITION CODE SUMMARY

9

ILLUSTRA

DESCRIPTION

CONTROL

FORMAT.

and

Write

OPERATIONS . .

CONSIDERATIONS •

INSTRUCTIONS

TIONS

· ·

·

PANEL

Instructions

Disc

Address

·

. . .

CONSIDERATIONS .

·

·

· · ·

·

· ·

·

·

· ·

·

· ·

·

·

· ·

·

· ·

·

·

·

· ·

·

·

·

·

·

·

·

·

· ·

·

·

.

.
.

·

·

·

·

· ·

.

.

·

·

·

· ·

· ·

·

·

0-1

1-1

2-1

3-1

3-1

3-1

4-1

5-1

6-1

7-1

8-1

9-1

1/72

Figure

Figure

Figure

Figure

Figure

Figure

Figure

1-1.

2-1.

3-1.

7-1.

8-1.

8-2.

8-3.

Model

Operator

Six-Character

Disc

Top

Top

Bottom
Its

40

Disc

Control

Sector

View of a Model 41B

View

Carrying

Layout

of

a Model 41A

View

of a Model

Case

Drive

Panel

Disc

.

.

Address

Disc

Disc

41,

.

Pack

Pack

41A,

Models

. • • • . • . • •

in

Its

or

in

41B

40

Carrying

Its

Carrying

Disc

and

42

Case

Case.

Pack

in

Reference

.

Manual

1-1

2-1

3-2

7-2

8-1

8-2

8-3

iii

Contents

TABLES

Table

Table

Table

Table

Table

1-1.

2-1.

7-1.

7-2.

9-1.

Specifications

Operator

Control

Timings.

Overlap

Condition

Timings

Code

.

Panel.

.

Summary

1-3

2-2

7-1

7-3

.

9-1

i v

Models

40

to

42

Reference

Manual

1/72

This

manual
gramming
the

manual
fications; a description
read

and
ations;
of

all

Condition

is

intended

characteristics

are a general

write

instructions

operations;

Codes

on how

for

those

of

the

description

of

the

operator

discussions

to

mount

associated

who

are

Models

of

and

with

the

interested

40

and

42

the

Models
control
of

remove

panel; a thorough

multi-partition

disc

Models 40

in

Disc

40

packs;

and

the
Drives.

and

42; a

and

42.

INTRODUCTION

operating

timing

plus a summary

and

Included

table

of

discussion

consider-

pro-

in

speci-

of

Detailed

Operator
Operator

operating

Instructions,
Instructions,

instructions

Publication
Publication

may

be
No.
No.

found

in
40-023,
40-332.

the

Model 40

and

the

Model

Disc

42

Drive

Disc

Drive

1/72

Models

40 and

42

Reference

Manual

0-1

The

Models
devices
disc

Channel
tained
and

nation.
what

removable

The

joined to one

14

discs.

top

used

designed

drives

(F

AC). A

in

the

the

F AC. A
In

external

differentiates

disc

Model 40

inches

surface

The

for

in

recording

40

and

as

may

be

Disc

central

particular

packs.

uses a disc

another

diameter

disc

pack

of

the

top

42

Disc

Drives

peripheral

attached

processor,

appearance,

them

on a

and

(Model 41

disc

data.

to

Controller,

installation

is

the

pack

common
there

and

are

high

units

for

the

central

consisting

acts

as

may

the

two

type

of

disc

consisting

vertical

is

approximately

Disc

Pack)

the

bottom

1

GENERAL

speed,

the

System

processor

of

printed

intermediary

include

models

pack

of

six

axis.

has

ten

surface

are

used.

magnetic

The

.4

of

random

Ten*

computer.

through

circuit

between

both

models

identical

Both

oxide

discs

inches

recording

the

between

bottom

DESCRIPTION

access

models

are

storage

Up

the

File

Access

cards

the

in

(see

coated

approximately

surfaces.

disc

con-

disc

any

Figure

use

successive

are

to

drives

combi-

discs

The
not

ten

1-1);

*A

trademark

1/72

of

The

Singer

Figure

Company

1-1.

Model 40

Models

Disc

Drive

40 and 42

Reference

Manual

1-1

General

Description

The

Model 42

packs

must
(Model 41A
(Model 41B
terminology,

When

both

It

is

anticipated

of

time

with

as

dictated
removable
another

diameter

pack
and
ing

On

tains

has

the

data.

all

200

on a

and

four

bottom

three

concentric
sectors.
always

writes

uses a pair

be

mounted
Disc
Disc

both

packs

the

by

the

pack

common

there

recording

surface

disc

Each

on

for
Pack)
Pack)

is
is

packs

are

mounted,

that

the

removable

requirements

each

consist

vertical

is

approximately

of

packs

(Models

tracks

sector

or

contains

reads

of

disc

packs,

the

disc
referred
referred

can

be

removed

they

resident

pack

pack

being

of

of

three

axis.

surfaces.

the

bottom

41,

and

each

100

from a single

one

drive

to

to

as

the

to

as

the

from

rotate

together
will
changed

each

installation.

magnetic

The

discs

0.4

inch

The

top

disc

of

41A,

and

track

characters.

sector.

mounted
be

operable.
resident
removable

the

disc

remain

from

oxide

are

between

surface

each

pack

41B)

is

divided

A

on top of

pack

pack.

drive

as

though they

mounted

run

The

coated

The

bottom

and

Regardless

by

for

to

run,

resident

discs

the

the

approximately

successive

of

the

top

disc

are

not

used

each

recording

into

50

equal

write

or

read

other.

pack

top

pack

the

operator.

were

extended

day

to
pack
joined

14

inches

discs.

of

each

for

surface

parts

operation

Both

of

one

pack.

periods

day,

and

the

to

one
in

Each

pack

record-

con-

called

the

etc.,

The

Model

41

characters.

storage

The
for
arm

The
mechanism
Model 40

Like

capacity

read/write

each

interdisc

and

the

read/write

Disc

all

peripheral

is

independently
panels.
and
STOP
is
cator
dri

When

When
to

The
bined
the

Once a pack

the

power

switch

rotating

light

ve

is

in

in

local,

on-line,

Read

and

ENAB

ON LINE

DISABLE

at
on
either

LE/DISAB

Disc

The

Models
of 4

head

other

head

identical

Drive

powered

is

on,

on

the

an

acceptable

the

the

the

Write

and

position,

Pack

has a maximum
41A

million

mechanism

gap.

Each

for

the

surface

mechanism

in

appearance

except

devices

and

(or a pair

the

operator

operator

operator
of two

disc

disc

states,

drive

drive

instructions

LE

switch

LOCAL

the

disc

and

41B

characters.

of

the

arm

has
below

of

the

that

the

for

the

System

are

turned
of

packs
starts

control

operational

control

panel

called

is

disconnected

can

perform

executed

on

the

switch.

drive

data

Disc

Packs

Model 40

'two

heads:

the

Model 42

to

the

middle

Ten

on

and

in

the

the

panel

to

speed

turns

local

read

in

the

operator

When the'

is

in

local.

storage

arm.

read/write

of

the

computer,

off

case

pack

the

(2400

on.

and

from

and

central

control

capacity

each

Disc

Drive

one

for

All

five

Disc

Drive

five

arms

from

their

of

the
rotating
START

rpm

With

on-line.

the

central

write

processor.

have a maximum

the

arms

head

the

own

Model 42)

by

position.

± 2%),

the

power

operations

panel

ENABLE/DISABLE

When

the

READY

of 10

has

five

surface

move

has

four

mechanism

is

missing.

disc

drives

operator

is

moving

the

When

the

READY

on,

processor.

in

serves

as a com-

switch

light

million

data

arms,
above

together.

arms.

of

are

control

mounted

START

the

the

disc

response

is

is

one

the

The

the

/

pack

indi-

in

on

1-2

Models

40

and

42

Reference

Manual

1/72

and

the

on-line.

The

Models

Table

ENABLE/DISABLE

40

and

42

Disc

1-1.

switch

Drives

is

in

the

operate

ENABLE

within

position,

the

specifications

General

the

Description

disc

drive

shown

is

in

Dimensions

Inches

Centimeters

Minimum

Service

Inches

Centimeters

Approximate

Maximum

Electrical

Voltage

Range
Frequency
Current
Maximum

Phases

KVA

Operating

Temperature
Relative

Clearances

Weight

Heat

Output/Hour

Requirements

Current

Surge

Environment

Humidity

Table

Floor

1-1.

Specifications

Width

30-1/4

77

Front

36
91

321

lbs

146

kg

3,9000

110-130V
60 ± 1

9.6A
45A

for 5 to

single

1.1

65

to

85°F

Rear

(without

(without

BTU

± 10%

Hz

10

36
91

20

Depth

24

61

10

4.5

secs

to

lb
kg

75%

Height

Right

0

0

disc

pack)

disc

pack)

982.8

kcal

208-230V ± 10%
50 ± 1

Hz

5.0A

25A

for 5 to

single

1.1

18

to

29.5

38
97

0

C

Left

0
0

10

secs

1/72

Non-Operating

Environment

Temperature
Relati

ve

Humidity

(Storage)

-30

to + 150°F

Models

40

8

to

and

80%

42

-34

to

Reference

+660C

Manual

1-3

The

operator
comprise
switch

and

three

light

control

toggle

is

discussed

panels

switches

of

in

the

and
Table

2

Models

three

2-1.

OPERATOR

40

and

42

Disc

indicator

lights.

CONTROL

Drives

The

(Figure

function

PANEL

2-1)

of

each

1/72

Figure

2-1.

Operator

Models

Control

40

and

Panel

42

Reference

Manual

2-1

Operator

Control

Panel

Control

POWER

POWER

ENABLE/DISABLE

START/STOP

READY

ON/POWER

Indicator

Switch

Indicator

Table

OFF

Light

Switch

Light

2-1.

Switch

Operator

Turns

Illuminated

When

switch

disc

drive

the

DISABLE

in

local.

When
position,
set

of

disc

surfaces,
emerges
most
the

STOP
tracts
the

pack

Provided
exists,
the

disc

speed

Control

the

power

the

READY

is

in

this

switch

the

brushes

and

track.

position,

into

slows

that

the

pack

(2400

Panel

Function

on

whenever

light

the

ENABLE

is

on

-line.

position,

is

disc

pack
cleans
and

positions

When

the

wall

to a halt.

no

FILE

READY

is

rotating

rpm

+ 2%).

and

moved

then

this

the

of

light

off.

the

power

is

on
position,

If

this

the

disc

to

begins

any

dust

the

head
itself
switch
head

assembly

the

disc

UNSAFE

is

on

at

the

is

on.

and

this

switch

drive

the

START

rotating,

from

assembly

at

the

is

moved

drive

condition

whenever

proper

the

is

in

is

the

outer-

re-

and

a

to

2-2

FILE

Models

UNSAFE

40

and

Indicator

42

Reference

Light

Manual

The

FILE

UNSAFE

ever

the

disc

which

recorded
light
tion
immediately,

-respond
turn

operator

switch
(after
the
ST

could

data.

turns

currently

to

off

the

must

to

the

the

pack

START/STOP

ART

position.

light

drive

detects a malfunction

conceivably

When

on, any

any

FILE

in

progress

and

the

further

move

STOP

has

read

UNSAFE

position

slowed

switch

turns

result

the

FILE

or

write

is

disc

drive

instructions.

light,

the

START/STOP

and

to a halt)

back

on

when-

in

loss

UNSAFE

opera-

terminated

cannot

To

the

then

move

to

the

of

1/72

3

INSTRUCTION

FORMAT

READ AND

SIX-CHARACTER

WRITE

A

Read

characteristics:

•

Both

•

The A -field
For a Read
record
area

•

The B -field
The
separate

Both

•
index

The

six-character

Read

or

•

The

INSTRUCTIONS

or

Write

the

from

segment

DISC ADDRESS

Write

disc

instruction

LA-field

specifies

instruction,

will

be

which

specifies

contains a six-character

topic

the A -field

register

segment

instruction

drive

and

read.

the

below) .

and B

if

the

contains

device

which

the

the

For a Write

record

the

-field

programmer

of

number

addresses a disc

LB-field

address

the

segment

will

address

may

memory

the

(0-9).

must

of a

100-location

is

the

instruction,

be

written.

of a

six-character

disc

be

modified

so

desires.

which

following

is

be

zero.

input

address

pointed

pieces

drive

the

by

the

has

segment

area

into

segment

segment

(discussed

contents

to

by

of

information~

the

which

the

following

of

memory.

the

is

the

output

of

memory.

as

a

of

an

B-field

of

the

1/72

The

•

The
Model

•

The

•

The

upper

format

arm

number

42, 0 specifies

track

sector

head

of

the

number

number
and

six-character

(0-4;

(000-199,

(00-99,

sectors

on

the

50-99

the

Model 40, 0

bottom

where

where

by

disc

address

Models

arm).

000

sectors

the

lower

specifies

specifies

00-49

head).

is

shown

40

and

the

the

are

in

Figure

42

Reference

top

arm;

outermost

accessed

3-1.

Manual

on

track)

by

the

the

.

3-1

Instruction

Only
information.
tion

Format

the

is

specified

numeric

Bit 7 may

portions

as

follows:

(1-4)

be

either 0 or

of

each

character

1;

bit 5 must

are

always

used

for

be

1.

specifying

The

informa-

this

(2)DEVICE

r0

HUNDREDS

L.:..I

THREE

~

TENS

~DIGIT

r0

UNITS

l!IDIGIT

NUMBER

DIGIT

DIGIT

TRACK

DIGIT

TRACK

I

CHARACTER

(0-9)

DIGIT

TRACK

(0-9)

OF A THREE

NUMBER

(0-9)

NUMBER

(0

OF A THREE

or

1)

OF

NUMBER

A

1

\(&3

D

A T T

D

A T T

D

A

D

T

4

!

T

T

T

T

f5\

TENS

L./DIGIT

f6\ UNITS

L.iDIGIT

[0ARM

5 6

S S 4

S

S

S

S

S S 1

DIGIT

SECTOR

DIGIT

SECTOR

NUMBER

(0-9)

(0-9)

Bit

3

2

OF

A TWO

NUMBER

OF

A TWO

NUMBER

(0-4)

NOTE:

•

The

bits

in

•

Bit 1 has
Bit 2 has
Bit 3 has
Bit 4 has

The

bits

Bit 1 has
Bit 2 has
Bit 3 has
Bit 4 has

Figure

characters

the

value 1 when

the

value 2 when

the

value 4 when

the

value 8 when

in

character 2 have

the

value 1 when

the

value 1 when

the

value 2 when

the

value 4 when

3-1.

1,3,4,5,

it

is

ON.

it

is

ON.

it

is

ON.

it

is

ON.

the

it

is

ON.

it

is

ON.

it

is

ON.

it

is

ON.

Six-Character

and 6 have

following

Disc

AddreSS

the

values:

following

values:

1/72

3

-2

Models

40

and

42

Reference

Manual

A

Write

accessed

instruction

from

memory

which

and

addresses a disc

written

onto a

drive

sector.

4

WRITE

causes

1

100

characters

OPERATIONS

to

be

If a Write

tion

is

terminated

are

set

on.

and

attached

42

Disc

When

errors.
sector
the
the
sidered

passes

Write

content

successful.
repeated
operation
the

operation

is

set

on.

If a Write
sector
tion

is

is

terminated

on.

If

a

FILE
terminated
set

on.

NOTE:

the

If

instruction

instruction

addresses a disc

and Condition

to

the

Disc

Drives

automatically

After a record

the

read/write

instruction's

of

the

Write

If

up to two

still

instruction

more

has

not

is

terminated,

addresses

one which would

and Condition Code 3 (Flag) in

UNSAFE

condition

and Condition

the

Disc

Controller

is

acted

Controller

(100

characters)

heads

output

area.

instruction's

the

operation

times.

been

successfully

and

be

accessed

occurs

Codes

is

upon

as

drive

which

Codes

4 and 1 (Fault)

of a

System

performed a "read

has

been

the

sector

If

the

content

output

is

If,

after a total

area,

unsuccessful,

performed,

Ten

written,

is

read

of
the

of

is

after

the

three

the

Condition Code 3 (Flag)

a Model 42

during a write

4 and 1 (Fault)

addressed

though

Disc

by

the

middle

in

by a Write

it

were a Write

Drive

arm

the

central

operation,

the

not

on-line,

in

the

central

computer,

write"
the

and

compared

sector
write
writing

operation

(and
attempts,
sector

in

the

and

the

(arm

processor

the

central

processor

Control
instruction.

the

instruc-

processor

the

Models

to

check

next

time

against

exactly

matches

is

reading)

the

write

is

marked

central

processor

requested

2),

the

instruc-

operation

instruction,

the

con-

is

are

40

for

is

''bad,''

set

is

1

A

write

address

1/72

operation

is

used

for

also

track

records

address

the

track

verification

address

on

during

Models 40 and 42

the

particular

disc

read

sector.

operations.

Reference

This

track

Manual

4-1

A

Read

instruction

contained

If

a

is

terminated

set

on.

If

the
three
successfully
the

central

If

a
is

one

terminated

If

a
terminated

on.

Read

specified
more

Read

which

FILE

in a sector

instruction

instruction

UNSAFE condition

which

and Condition

sector

times.

read,

proces

would

and Condition Code 3 (Flag)

and Condition

If,

the

sor

be

addresses a disc

to

be

read

into

addresses a disc

Codes

cannot

after a total

operation

is

set

on.

addresses

accessed

Codes

4 and 1 (Fault)

be

successfully

of

is

terminated

a Model
by

the

occurs

during a read

4 and 1 (Fault)

main

four

drive

memory.

drive

attempts,

42

Disc

middle

in

the

causes

which

read,

and

Drive
arm
central

in

5

READ

the

is

not

on-line,

in

the

central

reading

the

sector

Condition Code 1

and

(arm

2),

processor

operation,

the

central

OPERATIONS

100

characters

processor

is

retried

still

the

requested

the

operation

is

the

processor

the

instruction

up

cannot

(Error)

set

on.

operation

are

are

to

be

in

sector

is

is

set

Track

System

If

address

tion

on.

If

at
the
to

NOTE:
instruction

address

Ten

an

attempt

is

terminated

address

the

wrong

central

the

outermost

If

verification

verification

disc

read

is

made

and

verification

track,

process

the

is

track

Disc

acted

the

Controller

is

performed

operation.

to

read a sector

reveals

Condition Code 3 (Flag)

is

set

upon

that

reveals

operation

on, and

(track

as

000).

is

though

that

which

the

sector

the

read/write

is

terminated,

the

read/write

addressed

it

were

automatically

has

been

has

not

been

in

the

central

heads

Condition Code 1

head

by a Read

.a

Read

instruction.

at

the

beginning

marked

mechanism

Control

''bad''

initialized,

processor

have

been

instruction,

of a

or

if

the

opera-

is

positioned

(Error)

is

repositioned

set

in

the

1/72

Models

40

and

42

Reference

Manual

5-1

A

disc

drive
bound to a
drive

which

put

operation

partition

In

an

installation
forming
data

The

If

several
control
empts

seeks

at a time.

Disc

of

the F AC
partition
control

of
mechanism
head

mechanism,

and

the

disc

If

an

instruction
partition
processor

is

free

partition

is

bound

is

complete.

may

initiate a seek

containing

simultaneously;

Controller

seeks
the

are

central

for

may

read

the

central

to

another

drive

addresses a disc

in

which

and

does

for

use

as

soon

to a partition

remembers

being

processor

data

transmission.

and/or

processor

track.

the

partition

is

freed.

the

instruction

not

regain

6 MULTI-PARTITION

if

it

is

not

as

the

partition
remains

When a

upon

disc

that

several

however,

which

performed

after

write

sectors

and

If

the

relinquishes

drive

is

control

bound

drive.

disc

simultaneously,

that

Once

does

partition

executed

until

to a partition. A disc

initiates a seek

so

until

drive

is

bound

drives,

only one

disc

all

drive

drives

partition's

data

transmission

as

long

as

not

try

to

attempts

control

which

is

bound

relinquishes

the

disc

CONSIDERATIONS

drive

1 upon

the

associated

to a partition,

the

drives

may

are

bound to

the

first

seek

is

the

partition

move

the

to

move

of

the

central

to

another

control

drive

is

that

input

may

be

transmitting

which

partition

complete

is

begun,

maintains

read/write

the

read/write

processor

partition,
of

free.

be

is

drive.

or

out-

no

other

per-

partitions.

to

gain

pre-

the

head

the

central

A

the

1

The

term
proper
processor.

1/72

If

an

instruction

that

the
becomes
quishes
seek

is

"seek"

track

in

read/write

bound) and

control

complete.

refers

response

addresses a disc

head

mechanism

the

partition

of the

to

to a

central

the

act

Read

processor

of

moving

or

drive

in

Write

which

be

moved,

which

the

and

the

read/write

instruction

Models 40

is

free

the

seek

instruction

does

not

head

executed

and

42

but

the

is

initiated

is

executed

regain

mechanism

in

Reference

operation

control

the

central

Manual

(the

relin-

until

to

requires

drive

the

the

6-1

7

TIMING

CONSIDERATIONS

Table
Models

Minimum
wri
positioning
nism
of
track

Once
operation

necessary,

(0

te

from

time

the

to

25

7-1

40 and

head

required

199.

read/write

ms.)

shows

arm

takes

some

42

Disc

positioning

mechanism

time

is

track

000
to

0.5

and

the

each

retry

Arm

the

to

move

head

to

25.5

time

takes

of

the

more

Drives.

Rotation

Positioning

Minimum

Average

Maximum

time

from

one

amount

track

the

mechanism

ms.

needed

25

important

Table 7 -1.

Time

is

the

amount

track

of

time

099.

Maximum

read/write

is

These

to

read a sector

ms.

operational

Timings

Times

to

the

next

required

head

positioned

figures

25.0

ms.

2.5

ms.

73.0

ms.

135.0

of

time

to

arm

mechanism

include

ms.

required

sequential

move

positioning

at

the

the

(0.5

timings

to

track. A verage

the

read/write

time

from

tack

proper

rotational

ms.).

If

retries

for

the

move

the

read/

arm

mecha-

is

the

amount

000

to

track, a read

delay

time

are

1

1

Rotational
the

read/write

1/72

Once

the

operation

the

•

•

the
timing

•

the

•

the
the

delay

heads.

read/write

takes

26.5

rotational

amount

amount

amount
sector

time

of

algorithm

of

(25

is

the

head

to

delay

time

of

time

time

ms.).

amount

mechanism

51.5

ms.

time

required

(1

ms.)

required

required

of

These

(0

to

time

is

positioned

figures

25

ms.)

for

the

Disc

to

write a sector

to

rotate

needed

Models 40

include:

Controller

to

the

for

the

to

at

the

(0.5

sector

desired

42

Reference

proper

to

ms.)

and

track, a write

execute a special

then

to

read

sector

to

move

Manual

to

7-1

Timing

Considerations

The

disc

is

formatted

as

shown

63

in

Figure 7 -1.

73

83

93

61

51

90

NOTE:

Sector

50-99

0-49

are

are

accessed

accessed

98

by

88

the

78

by

the

lower

68

upper
head.

head

on

each

arm,

and

95

56

66

sectors

Figure

7-1.

Disc

Sector

Layout

1/72

7

-2

Models

40

to

42

Reference

Manual

After

reading

which

disc

may

is

the
formatted
the

fifth

read

and

When

performing

using

consecutively

the

same

heads

after
executed
tional

instructions
amount

right

column

able

for

exceeded,

second

operation.

or

writing a sector,

be

read

fifth

sector

such

that

sector

following

write a series

any of

track,

the

it

takes 2 ms.

first

consecutively,

are

of

time

wasted

of

Table

computation

an

additional

or

written

following

sector 2 is

sector

of

consecutively

the

numbered

operation

the

entire 2 ms.
inserted
can

be

7

-2

specify

be~een

revolution

the

without

the

one

the

fifth

2,

etc.

pairs

of

read/write

sectors

for

the

is

finished.

between

significantly

the

the

two

of

first

subsequent

requiring

read

sector

This

numbered

(e.g.,

sectors 1 and

second

If

is

wasted

the two

reduced.

absolute

disc

I/O

the

disc

sector

an

additional

or

written.

following

means

that

sectors.

operations

sector
the

two

to

disc

move

time.

disc

I/O

The

maximum

instructions.

(25

ms.)

will

Timing

Considerations

on

the

revolution

Notice

sector

it

I/O

that

1,

is

very

shown

2,

48

and

to

the

instructions

sector 3 is

in

However,
instructions,

figures

amount

If

the

be

required

shown in
of

times

same

track

of

the

the

disc

efficient

Table

49,

7-2

etc.)

read/write

are

if

computa-

the

the

time

avail-

are

for

the

is

to

on

NOTE:

The
algorithm
available
pair

of

disc

Disc

at

the

for

computation

I/O

instructions.

Controller

start

of a

Table

7

-2.

Read

Re!:lrl

.-.,

---

Write

Write

Write

Read

Read

Write

takes 1 ms.

write

operation.

when a

Write

Overlap

to

perform

Therefore,

instruction

Timings

1.6

ms.

.6

ms.

1.6

ms.

.6

ms.

the

is

the

special

only 0.6

second

timing

ms.

is

in

the

1/72

Models 40

to

42

Reference

Manaul

7-3

The

Models

See

Figure

To

mount a disc

a.

Lift

b.

Holding
counterclockwise

c.

Place

d.

Turn

e.

When

41,

8-1,

the

the

the

the

41A,

8-2,

pack

carrying

the

pack

pack

handle

handle

and41B

and

8-3.

(Model 41)

case

by

upside

until

the

on

the

spindle

on

the

top

will

no

Disc

Packs

on a Model

the

down,

bottom

of

longer

top

turn

in

the

handle.

of

the

case

turn,

8

OPERATING

each

have

their

40

Disc

the

knob on

the

case

comes

center

lift

of

the

clockwise.

the

case

own

Drive,

the

bottom

disc

out

INSTRUCTIONS

carrying

proceed

off.

pack

of

the

of

cases.

as

follows:

the

case

compartment.

compartment.

1/72

Figure

8-1.

Top

View of a Model 41B

(Model 41

is

identical

except

Models

Disc

40

Pack

in

for

identification

to

42

Reference

Its

Carrying

Case

marking)

Manual

8-1

Operating

Instructions

To

mount

follows:

a.

Lift

b.

Holding
counterclockwise

c.

Place

d.

Lift
out

the

the

the

of

bottom

Carrying

the

pack

the

pack

release

the

compartment.

Do

not
and
Disc
40

and

pack

upside

on

knob

41B

packs

(Model 41A) on a Model 42

case

by

the

top

handle.

until

the

spindle

on

under

Disc

are

Model

down,

the

the

any

Packs

42

turn

bottom

circumstances

not

Disc

of

in

the

top of

the

CAUTION

on a

Model

interchangeable

Drives.

the

the

center

carrying

knob on

case

comes

of

the

mount

40

Disc

between

Disc

the

disc

case

Model

Drive.

Drive,

bottom

off.

pack

and

41A

Model

proceed

of

the

case

compartment.

lift

the

case

as

8-2

Models

Figure

40

to

8-2.

42

Reference

Top
(note

View

the

Manual

of

a Model 41A

release

button).

Disc

Pack

in

Its

Carrying

Case

1/72

To

mount

follows:

a.

Lift

b.

Holding
counterclockwise

c.

Place

two

resident
movable

together.

one

d.

When

it

clockwise.

e.

When

the

top

the

carrying

the

the

pack

packs

direction

the

the

are
pack
pack.

The

packs

handle

pack

(Model 41B) on a Model

case

by

the

pack

upside

on

aligned.

and

When

operator

or

the

are

will

until

top

of

this

the

other

properly

no

down,

the

the

There

pin

pin

may

longer

bottom

resident

should

is
have

to

top

handle.

turn

is a pin

fit

in

the
to

cause

joined,

turn,

42

the

knob on

of

the

case

pack

protruding

into a hole

hole,

turn

the

the

pack

press

lift

the

Disc

the

comes

so

that

in

the

two

removable

to

drop

the

top

case

Operating

Drive,

bottom

off.

the

large

from

the

bottom

packs

into

handle

out

of

proceed

of

the

arrows

the

top

of

are

locked

pack

slightly

place.

down

the

compartment.

Instructions

as

case

on

the

of

the

the

re-

in

and

turn

1/72

Figure

8-3.

Bottom

41B

Disc

View of a Model

Pack

in

Its

Carrying

Models

40

to

42

41,

41A,

Case

Reference

or

Manual

8-3

Operating

Instructions

To

remove a disc

top

pack

(Model 41B)

a.

Place

b.

Turn

c.

When

d. Holding

the

To

remove

as

follows:

a.

Place

b.

Press
case

c.

Holding
the

the

the

the

pack

the

the

the

out

pack

pack

top of

handle

pack

the

pack

and

bottom

top of

release

of

the

the

pack

and

(Model 41)

from

a Model 42

the

carrying

on

the

begins

turn

compartment.

turn

upside

the

pack

the

carrying

knob on

upside

the

to

knob on

(Model 41A)

knob on

top

turn

down,

down,

from

of

the

a Model 40

Disc

case

the

case

freely,

place

the

bottom

case

top of

place

the

bottom

Disc

Drive,

on

the

counterclockwise.

lift

the

from

on

the

the

the

proceed

pack.

the

case

bottom

of

the

a Model

pack.

carrying

bottom

of

the

out

of

the

case

42

case

of

the

case

Drive

or

as

follows:

of

the

carrying

clockwise.

Disc

Drive,

and

carrying

clockwise.

to

remove

compartment.

case

on

proceed

then

lift

the

case

on

the

Before

that

the
come
pin

is
with
pack.
for

to a halt.

tries

sheared

Never
rotating.

extended

the

Always

the

lifting

START/STOP

turn

pack

to

off.

If

disc

the

If

extend

If

the

the

POWER

the

power

from

pack

move

to

come

the

cover

to

switch

the

cover

into

holes

locking

switch

is

turned

wall

recording

the

START/STOP

to a halt

the

is

is

in

pin

of

the

surfaces

CAUTION

disc

pack

in

the

raised

the

bottom

is

sheared

to

the

off

when

drive,

before

compartment,

STOP

while

OFF

causing
switch

turning

off,

the

the

position

the

of

position

read/write

heads

to

off

and

pack

is

the

pack

the

disc

when

could

permanent

the

STOP

the

power.

check

and

drive

come

to

be

sure

that

the

pack

rotating, a locking

the

pin could

is

unusable.

the

disc

pack

head

mechanism

in

contact

damage

position

to

and

the

has

be

is

wait

8-4

Models

40

to

42

Reference

Manual

1/72

9

CONDITION

CODE

SUMMARY

Table
40 and 42

9-1

Condition

1

(Error)

2 (Normal)

3 (Flag)

summarizes

Disc

Drives.

Codes

the

various

Table

9-1.

Sector

Read/write

could

OR

O.K.

Instruction
a Model 42

OR

Sector

Attempted

Attempted
initialized.

could

OR

OR

Condition

Condition Code

not

be

heads

addressed

Disc

Drive.

not

be

to

read a sector

to

read

Codes

Meaning

read.

positioned

the

written

or

write a sector

associated

Summary

at

wrong

non-existent

on.

which

was

which

with

track.

arm

(arm

marked

had

the

Models

2)

''bad.''

not

of

been

1/72

4 and 1 (Fault)

Disc

drive

OR

FILE
operation.

UNSAFE condition

not

on-line.

Models 40 to 42

sensed

during a read

Reference

Manual

or

write

9-1

51

R

Printed

Holland