MC68HC08AZ60A Datasheet, PDF (55/480 Pages) Motorola, Inc – Microcontrollers

Advance Information — MC68HC08AZ60A
Section 3. RAM
3.1 Contents
3.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
3.3 Functional Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55
3.2 Introduction
This section describes the 2048 bytes of random-access memory
(RAM).
3.3 Functional Description
Addresses $0050 through $044F and $0A00 through $0DFF are RAM
locations. The location of the stack RAM is programmable with the reset
stack pointer instruction (RSP). The 16-bit stack pointer allows the stack
RAM to be anywhere in the 64K-byte memory space.
NOTE: For correct operation, the stack pointer must point only to RAM
locations.
Within page zero are 176 bytes of RAM. Because the location of the
stack RAM is programmable, all page zero RAM locations can be used
for input/output (I/O) control and user data or code. When the stack
pointer is moved from its reset location at $00FF, direct addressing
mode instructions can access all page zero RAM locations efficiently.
Page zero RAM, therefore, provides ideal locations for frequently
accessed global variables.
Before processing an interrupt, the CPU uses five bytes of the stack to
save the contents of the CPU registers.
MC68HC08AZ60A — Rev 0.0
MOTOROLA
RAM
Advance Information
55