ZiLOG Z8 Technical Manual

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CALL

Call Procedure

CAll

dst

Instruction

Format:

Cycles

OPC

(Hex)

Address

Mode

dst

~

______

OP_C

______

~I

~I

_______________

d_s_t

______________

~

20

06

OA

~

______

O_P_C

______

~1

~I

_______

ds_t

______

~

20

04

IRR

Operation:

Flags:

Example:

Note:

5-10

SP

<--

SP

- 2

QSP

<--

PC

PC

<--

dst

The

current

contents

of

the

PC

are

pushed onto

the

top

of

the

stack.

The

PC

value

is

the

address

of

the

first

instruction

following

the

CALL

instruction.

The

specified

destination

address

is

then

loaded

into

the

PC

and

points

to

the

first

instruction

of

a

procedure.

At

the

end

of

the

procedure a

R£Turn

instruction

can be used

to

return

to

the

original

program flow.

RET

pops

the

top

of

the

stack

back

into

the

PC.

No

flags

affected.

If

the

contents

of

the

PC

are

%1A47

and

the

contents

of

the

SP

(control

registers

254-5)

are

%3002,

the

statement

CALL

%3521

causes

the

SP

to

be decremented

to

%3000,

%1A4A

(the

address

following

the

instruction)

is

stored

in

external

data

memory

%3000-%3001,

and

the

PC

is

loaded with

%3521.

The

PC

now

points

to

the

address

of

the

first

statement

in

the

procedure

to

be

executed.

When

used

to

specify

a

4-bit

working-register

pair

address,

address

mode

IRR

uses

the

format:

E

dst

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ZiLOG Z8 Specifications

General

Brand	ZiLOG
Model	Z8
Category	Desktop
Language	English

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