Freescale Semiconductor, Inc.
Technical Data — MC68HC908AS60
Section 3. Random-Access Memory (RAM)
3.1 Contents
3.2
3.3
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
3.2 Introduction
This section describes the 2048 bytes of random-access memory
(RAM).
3.3 Functional Description
Addresses $0050–$044F and $0A00–$0DFF are the 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 64-Kbyte 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.
MC68HC908AS60 — Rev. 1.0
Technical Data
Random-Access Memory (RAM)
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