Chapter 7 central processor unit (cpu), 1 introduction, 2 features – Freescale Semiconductor MC68HC908MR32 User Manual

Page 79: 3 cpu registers, Chapter 7, Central processor unit (cpu), Introduction, Features, Cpu registers

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MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1

Freescale Semiconductor

79

Chapter 7
Central Processor Unit (CPU)

7.1 Introduction

The M68HC08 CPU (central processor unit) is an enhanced and fully object-code-compatible version of
the M68HC05 CPU. The CPU08 Reference Manual (document order number CPU08RM/AD) contains a
description of the CPU instruction set, addressing modes, and architecture.

7.2 Features

Features of the CPU include:

Object code fully upward-compatible with M68HC05 Family

16-bit stack pointer with stack manipulation instructions

16-bit index register with x-register manipulation instructions

8-MHz CPU internal bus frequency

64-Kbyte program/data memory space

16 addressing modes

Memory-to-memory data moves without using accumulator

Fast 8-bit by 8-bit multiply and 16-bit by 8-bit divide instructions

Enhanced binary-coded decimal (BCD) data handling

Modular architecture with expandable internal bus definition for extension of addressing range
beyond 64 Kbytes

Low-power stop and wait modes

7.3 CPU Registers

Figure 7-1

shows the five CPU registers. CPU registers are not part of the memory map.

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