Computer Hardware

Spectra 70

RCA Spectra 70 Training Manual

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The

Read

Device

Reverse

(RDR)

can

be

issued

only

to

magnetic

tape.

The

instruction:

OPERATION

OPERAND

RDR

4(1),

INPT

+ 79,

INPT

causes

the

magnetic

tape

to

be

moved

in

a

reverse

direction.

The

first

byte

read

is

placed

in

INPT+79

(HSM

1079),

the

second

byte

is

placed

in

INPT+78,

etc.,

and

the

last

byte

read

is

placed

in

INPT

(HSM

1000).

Note

that

the

addresses

had

to

be

reversed.

Once

staticized

and

accepted

by

the

channel

Control

Electronics,

I/O

instructions

are

executed

in

a

si-

multaneous

manner,

leaving

the

processor

free

to

staticize

the

next

instruction

in

sequence.

The

70/15

Read

Auxiliary

instruction

(RDA)

is

recog-

nized

and

executed

on

the

70/25

as

a

Read

Device

Forward,

and

does

not

initiate

an

Operation

Code

Trap

interrupt.

Notice

that

both

the

RDF

and

RDR

instructions

are

terminated

by:

1.

Reaching

a

gap

on

magnetic

tape

or

reading

one

card,

or

2.

Reading

the

amount

of

data

specified

by

the

ad-

dress

operands.

WRITING

DATA

The

Write

instruction

(WR)

transfers

data

from

HSM

to

the

selected

device.

The

instruction:

OPERATION

OPERAND

WR

3(1),

OUTP,

OUTP

+ 79

prints

the

contents

of

HSM

1200-1279

(OUTP

area)

to

the

Printer.

Base

addresses

are

implied.

The

same

command

with

channel

number

changed:

OPERATION

OPERAND

WR

4(1),

OUTP,

OUTP

+ 79

50

writes

a

block

of

eighty

bytes

to

tape

1

on

channel

4,

or

OPERATION

OPERAND

WR

2(1),

OUTP,

OUTP

+ 79

punches

a

card.

The

Erase

(WRE)

instruction

is

a

Write

command;

however,

it

can

only

erase

a

section

of

magnetic

tape.

The

instruction,

OPERATION

OPERAND

WRE

4(2),

OUTP,

OUTP

+ 50

erases

an

area

oftape

equal

to

the

length

of

51

bytes.

CONTROLLING

PERIPHERAL

DEVICES

The

instructions

discussed

above

serve

the

function

of

moving

data

in

and

out

of

HSM.

The

Write

Control

(WRC)

command

has

the

function

of

communicating

control

information

(rewind

tape,

paper

advance,

pocket

select,

etc.)

to

a

specific

device.

The

instruc-

tion

transmits

a

byte

from

HSM

to

the

Control

Elec-

tronics

of

the

selected

device.

The

bit

configurations

of

these

control

bytes

are

illustrated

below.

CARD

READER

Control

Byte

Select

Output

Stacker

#1

Select

Output

Stacker

#2

Translate

mode

Binary

mode

NOT USED

MAGNETIC

TAPE

Control

Byte

NOT USED

NOT USED

Reread

Unwind

one

gap

Rewind

one

gap

Rewind

and

Disconnect

Unload

without

Rewind

(cartridge

Tape

Only)

Rewind

to

BT

Marker

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Reference Manual260 pages

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RCA Spectra 70 Specifications

General

Brand	RCA
Model	Spectra 70
Category	Computer Hardware
Language	English

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