RCA Spectra 70 - Page 113

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Program Control

(PC)

General

Description

Format

(SI)

Condition Code

Interrupt

Action

Note

Privileged

Instructions

•

This

instruction

specifies

the

termination

of

program

execution

in

the

current

state,

and

the

initiation

of

another

state

under

control

of

the

immediate

byte

in

the

12

field.

The

address

computed

from

the

Bl/Dl

address components

of

the

instruction

is stored in

the

P

counter

of

the

state

being

terminated

(bit

positions

8-31).

82

o 7 8

15

16 19

20

31

• The condition code indicators

of

the

state

being

terminated

are

preserved

in

the

state's

P counter. The condition code

in

the

P

counter

of

the

initiated

state

is

then

used to

set

the

condition code indicators.

• Privileged operation.

Address

error:

Addressing.

• 1.

The

immediate

byte

in

the

12

field

of

the

instruction

is divided

into

four

subfields

as

follows:

8

9

10

11

12

13

14

15

\

.....

--_

r--...,I

V

\,-_~

.-_---J

1

v

Unused

Program

Test

Bit

Direct

State

Initiation

Indirect

Control

Flag

Bits 8 through

10

are

unused.

The

three

bit

unused

portion

must

be zero.

Bit

11 is

the

program

test

bit.

If

bit

11

= 1,

the

program

test

mode

is initiated.

The

program

test

interrupt

bit

is

set

in

the

Interrupt

Flag

register

of

the

initiated

state.

The

scan

of

the

Interrupt

Flag

register

in

the

initiated

state

is delayed

until

after

the

first

instruction

of

the

initiated

state

is executed,

at

which

time

the

scan

is

made

in

normal

priority.

If

bit

11 = 0,

the

program

test

mode is

not

initiated.

104

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