MC68HSC705C8ACFS datasheet(35/222 Pages) FREESCALE

35 / 222 page

MC68HC705C8A — Rev. 3

Technical Data

MOTOROLA

Memory

Technical Data — MC68HC705C8A

Section 2. Memory

2.1 Contents

2.2

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

2.3

Memory Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

2.4

Input/Output (I/O) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

2.5

RAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

2.6

EPROM/OTPROM (PROM) . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

2.7

Bootloader ROM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

2.2 Introduction

This section describes the organization of the on-chip memory.

2.3 Memory Map

The central processor unit (CPU) can address eight Kbytes of memory

and input/output (I/O) registers. The program counter typically advances

one address at a time through memory, reading the program instructions

and data. The programmable read-only memory (PROM) portion of

memory — either one-time programmable read-only memory

(OTPROM) or erasable, programmable read-only memory

(EPROM) — holds the program instructions, fixed data, user-defined

vectors, and interrupt service routines. The random-access memory

(RAM) portion of memory holds variable data.

I/O registers are memory-mapped so that the CPU can access their

locations in the same way that it accesses all other memory locations.

The shared stack area is used during processing of an interrupt or

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