Z8FMC16100 Series Flash MCU
Product Specification
277
eZ8 CPU Instruction Set
This chapter describes how to use the eZ8 CPU.
Assembly Language Programming Introduction
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
(Op Codes and operands) to represent the instructions themselves. The Op Codes 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 state-
ments. Each statement can contain labels, operations, operands and comments.
Labels can be assigned to a particular instruction step in a source program. The label iden-
tifies 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 lan-
guage program called the object code. The object code is executed by the eZ8 CPU. An
example segment of an assembly language program is detailed in the code below.
Assembly Language Source Program Example
JP START
START:
; Everything after the semicolon is a comment.
; A label called START. The first instruction (JP
START) in this
; example causes program execution to jump to the
point within the
; program where the START label occurs.
LD R4, R7
; A Load (LD) instruction with two operands. The
first operand,
; Working Register R4, is the destination. The
second operand,
PS024604-1005
P R E L I M I N A R Y
eZ8 CPU Instruction Set
ZILOG [ ZILOG, INC. ]
