Computer Hardware

Spectra 70

RCA Spectra 70 Training Manual

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INPUT

/OUTPUT

INTRODUCTION

The

user

may

elect

to

control

Input/Output

by

Assem-

bly

I/O

instructions

or

by

software

I/O

subroutines.

This

section

describes

the

eight

Assembly

I/O

in-

structions,

and

the

methods

of

error

recognition

and

recovery.

Up

to

nine

channels

connect

the

RCA

70/25

main-

frame

to

I/O

devices.

Each

channel

has

its

own

Control

Electronics,

and

is

capable

of

the

independent

execution

of

I/O

commands.

A

feature

called

MUL-

TIPLEXING

makes

it

possible

to

connect

many

devices,

printers,

card

readers,

etc.,

to

a

single

channel

without

the

loss

of

simultaneous

capabilities.

CHANNEL

0

I

CONTROL

ELECTROI'HCS

CHANNEL

1

CONTROL

ELECTRONICS

CHANNEL

2

CONTROL

"1

El

ECTRONICS

u

~

CHANNEL

3

CONTROL

"-

ELECTRONICS

RCA

~

70/2!J

"1

PROCESSOR

~

CHANNEL

4

CONTROL

ELECTRONICS

q

~

CHANNEL

5

CONTROL

~

~

EI

~

1;;

CHANNEL

G

CONTROL

JeT.

CHANNEL

7

I

CONTROL

1

ELECTRONICS

CHANNEL

R

I

CONTROL

MULTIPLEX

ELECTRONICS

I

DE\lCE

I

I

DEVICE

I

I

DEVICf:

I

I

DEVICE

I

I

DEVICE

I

I

DEVICE

I

I

DEVICE

I

I

DEVICE

I

~H

DEVICE

H

DEVICE

4

DEVICE

Up

tu

FI

trunks

on

a

Multiplex

I

I

I

Two

of

the

eight

channels

may

be

used

for

high-speed

transmission,

and

the

remaining

six

for

medium

speed,

or

all

eight

may

be

used

for

the

medium

speed.

The

high-speed

channels

must

be

the

first

two

(0

and

1)

channels.

To

these

channels

maybe

added

the

ninth

channel,

a

MULTIPLEX

that

accommodates

up

to

eight

trunks.

The

total

theoretical

data

rate

available

on

the

70/25

is

667KB.

Because

the

medium-speed

channels

and

multiplexor

take

more

time

to

process

each

byte

than

the

high-speed

channels,

devices

operating

on

the

slower

channels

must

have

their

peak

data

rates

mul-

tiplied

by

a

weighting

factor

in

the

determination

of

total

equivalent

data

rate.

These

weighting

factors

are

2.;)

for

a

device

operating

on

a

medium-speed

channel,

and

4.5

for

a

device

operating

in

multiplex

mode

on

the

multiplexor

channel.

(The

multiplexor,

however,

cannot

exceed

a

total

data

rate

of

ll1KB.)

49

The

following

configuration

is

assumed

for

all

ex-

amples

in

this

section.

CHANNEL

UNIT

DEVICE

1

1

1

CARD

READER

CARD

PUNCH

PRINTER

1

2

3

4

1,2,3,4

TAPE

STATIONS

READING DATA

Data

is

read

into

High-Speed

Memory

(HSM)

by

two

Read

Commands.

The

Read

Device

Forward

can

address

all

peripheral

equipment

on

line

to

the

sys-

tem.

The

Read

Device

Reverse

command

can

be

issued

only

to

tape

stations.

READ

INSTRUCTIONS

OPERATION

OPERAND

RDF

T(D),

D1

(B1)'

D2(B2)

RDR

T(D),

D1

(B

1

),

D

2

(B2)

These

commands

select

a

Channel

and

Device,

and

indicate

what

HSM

area

is

to

receive

the

data.

Assuming

the

two

HSM

areas:

INPT

(HSM

1000-1100)

OUTP

(HSM

1200-1319)

The

instruction,

OPERATION

OPERAND

RDF

1(1),

INPT,

INPT

+ 79

reads

a

card

from

the

Card

Reader

(Trunk

1)

into

HSM

location

starting

at

1000

(INPT)

and

ending

at

HSM

1079

(INPT+79).

Base

addresses

are

implied.

The

same

instruction

with

the

Trunk

number

changed:

OPERATION

OPERAND

RDF

4(1),

INPT,

INPT

+ 79

reads

a

block

from

magnetic

tape

filling

eighty

char-

acters

of

HSM

(1000-1079).

Table of Contents

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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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