MC68HC08AS32 Datasheet, PDF (55/394 Pages) Motorola, Inc – M68HC08 Family of 8-bit microcontroller units (MCUs)

Advance Information — MC68HC08AS32
Section 3. Random-Access Memory (RAM)
3.1 Contents
3.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55
3.3 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55
3.2 Introduction
This section describes the 1024 bytes of random-access memory
(RAM).
3.3 Functional Description
Addresses $0050–$044F are RAM locations. The location of the stack
RAM is programmable. The 16-bit stack pointer allows the stack to be
anywhere in the 1024-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.
MC68HC08AS32 — Rev. 3.0
MOTOROLA
Random-Access Memory (RAM)
Advance Information
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