MC68HC708AS48 FREESCALE [Freescale Semiconductor, Inc], MC68HC708AS48 Datasheet - Page 55

• Manufacturer Part Number: MC68HC708AS48
• Description: Advance Information
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

3.1 Contents
3.2 Introduction
3.3 Functional Description
MC68HC708AS48
MOTOROLA
Advance Information — MC68HC708AS48
NOTE:
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Rev. 4.0
Section 3. Random-Access Memory (RAM)
3.2
3.3
This section describes the 1,536 bytes of random-access memory
(RAM).
Addresses $0050–$064F are RAM locations. The location of the stack
RAM is programmable. The 16-bit stack pointer allows the stack to be
anywhere in the 1,536-byte memory space.
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.
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55
Random-Access Memory (RAM)
Advance Information
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