Instruction Set

10.2 Introduction

The MCU instruction set has 62 instructions and uses eight addressing modes. The instructions include all those of the M146805 CMOS Family plus one more: the unsigned multiply (MUL) instruction. The MUL instruction allows unsigned multiplication of the contents of the accumulator (A) and the index register (X). The high-order product is stored in the index register, and the low-order product is stored in the accumulator.

10.3 Addressing Modes

The CPU uses eight addressing modes for flexibility in accessing data. The addressing modes provide eight different ways for the CPU to find the data required to execute an instruction. The eight addressing modes are:

•Inherent

•Immediate

•Direct

•Extended

•Indexed, no offset

•Indexed, 8-bit offset

•Indexed, 16-bit offset

•Relative

General Release Specification

 

MC68HC05RC16 — Rev. 3.0

 

 

 

86

Instruction Set

MOTOROLA