Computer Hardware

Spectra 70

RCA Spectra 70 Training Manual

63 pages

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LOGICAL

INSTRUCTIONS

INTRODUCTION

The

Logical

Instructions

perform

operations

on

the

individual

bits

of

a

byte.

The

operation

works

from

the

left

to

right

on

equal

length

operands

(256

maxi-

mum).

Proper

parity

is

generated

for

each

byte

based

upon

the

eight

least-significant

bits.

The

three

principal

logical

operations

are

AND

(result

is

one

if

and

only

if

both

bits

are

one),

OR

(result

is

one

if

either

or

both

bits

are

one),

EX-

eLUSIVE

OR

(result

is

one

if

either

but

not

both

bits

are

one).

One

additional

logical

operation

is

a

test

comparison

with

a

specified

mask.

AND

INSTRUCTION

The

rule

of

the

AND

instruction

is

that

a 1

bit

in

the

same

relative

bit

pOSition

of

both

operands

produces

a 1

bit

in

the

same

pOSition

of

the

result.

Any

other

combination

of

bits

produces

a

zero

bit

in

the

result.

Example:

HSM

BEFORE

EXECUTION

HSM

BEFORE

AND

AFTER

EXECUTION

ASSEMBLY

INSTRUCTION

GENERATED

INSTRUCTION

HSl\l

AFTER

EXECUTIO~

o + 0 o

0+1

o

1 + 0

o

1 + 1 1

AD1

BIT

CONFIGURATION

30

00

01

0000

0000

1001

1010

00

9A

INC

00

01

31

1111

1111

1111

1010

FF

FA

OPERATION

OPERAND

NC AD1 (2), INC

OP

L

B1

D1

B2

D2

D4

16

1

110

3000

10

110

3100

10

General

Register

one

contains

0000

0000 0000 1001

10]0

CONDITION

CODE

= 1

45

OR INSTRUCTION

This

instruction

maybe

used

to

insert

1

bit(s)

in

any

bit

position

(s)

of

a

byte.

The

rule

of

OR

is

that

a 1

bit

in

the

same

relative

position

of

either

field

produces

a 1

bit

in

the

same

position

of

the

result.

Example:

HSM

BEFOHE

AND

AFTER

EXECUTION

HSM

BEFORE

EXECUTION

ASSEMBLY

INSTRUCTION

GENERATED

INSTRUCTION

HSM

AFTER

EXECUTION

0+0

o

o

+ 1 1

1 + 0 1

1

+ 1 1

('II

BIT

CONFIGURATION

0000 0000

0000

0000 0000

0001

BAL

1000 1001

1000

1100

General

Register

one

contains

0000

BAL

0000

0111

1000 1001

1000

1101

CONDITION

CODE

= 1

EXCLUSIVE

OR

INSTRUCTION

The

Exclusive

Or

instruction

extracts

1

bit(s)

in

specified

bit

position(s)

of

one

or

more

bytes.

The

Exclusive

Or

may

also

be

used

to

alternate

des-

ignated

bits

so

that

they

will

have

a

value

of

1

the

first

time

and

0

the

second

time

the

Exclusive

Or

in-

struction

is

performed.

In

this

case

the

modifying

mask

has

a

one

bit

in

the

bit

positions

where

the

inter-

change

is

desired.

The

rule

of

Exclusive

Or

may

be

considered

the

same

as

binary

addition.

However,

there

is

no

carry

from

one

bit

to

the

next.

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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