z8f083a ZiLOG Semiconductor, z8f083a Datasheet - Page 169

• Manufacturer Part Number: z8f083a
• Description: High-performance 8-bit Microcontrollers
• Manufacturer: ZiLOG Semiconductor

Assembly Language Programming Introduction
PS026308-1207
eZ8 CPU Instruction Set
The eZ8 CPU assembly language provides a means for writing an application program
without concern for actual memory addresses or machine instruction formats. A program
written in assembly language is called a source program. Assembly language allows the
use of symbolic addresses to identify memory locations. It also allows mnemonic codes
(Opcodes and operands) to represent the instructions themselves. The Opcodes identify
the instruction while the operands represent memory locations, registers, or immediate
data values.
Each assembly language program consists of a series of symbolic commands called
statements. Each statement contain labels, operations, operands and comments.
Labels are assigned to a particular instruction step in a source program. The label
identifies that step in the program as an entry point for use by other instructions.
The assembly language also includes assembler directives that supplement the machine
instruction. The assembler directives, or pseudo-ops, are not translated into a machine
instruction. Rather, the pseudo-ops are interpreted as directives that control or assist the
assembly process.
The source program is processed (assembled) by the assembler to obtain a machine
language program called the object code. The object code is executed by the eZ8 CPU. An
example segment of an assembly language program is given in the following example.
Assembly Language Source Program Example
JP START
START:
LD R4, R7
LD 234H, #%01
; Everything after the semicolon is a comment.
; Working register R4, is the destination. The second operand,
; Working register R7, is the source. The contents of R7 is
; The first operand, extended mode register Address
; value
; Another Load (LD) instruction with two operands.
; example causes program execution to jump to the point within the
; A Load (LD) instruction with two operands. The first operand,
; A label called “START”. The first instruction (
; program where the
; written into R4.
; identifies the destination. The second operand, immediate data
; register at address
01H
, is the source. The value
234H
START
.
label occurs.
Z8 Encore!
01H
is written into the
Product Specification
eZ8 CPU Instruction Set
JP START
®
F083A Series
234H
,
) in this
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