Справочник Пользователя для Motorola MC68HC908MR16
MC68HC908MR16/MC68HC908MR32 — Rev. 4.0
Advance Information
MOTOROLA
Random-Access Memory (RAM)
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Advance Information — MC68HC908MR16/MC68HC908MR32
Section 3. Random-Access Memory (RAM)
3.1 Contents
3.2 Introduction
This section describes the 768 bytes of random-access memory (RAM).
3.3 Functional Description
Addresses $0060–$035F are RAM locations. The location of the stack
RAM is programmable. The 16-bit stack pointer allows the stack to be
anywhere in the 64-Kbyte memory space.
RAM is programmable. The 16-bit stack pointer allows the stack to be
anywhere in the 64-Kbyte memory space.
NOTE:
For correct operation, the stack pointer must point only to RAM
locations.
locations.
Within page zero are 160 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 efficiently all page zero RAM locations.
Page zero RAM, therefore, provides ideal locations for frequently
accessed global variables.
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 efficiently all page zero RAM locations.
Page zero RAM, therefore, provides ideal locations for frequently
accessed global variables.
Before processing an interrupt, the central processor unit (CPU) uses
five bytes of the stack to save the contents of the CPU registers.
five bytes of the stack to save the contents of the CPU registers.
NOTE:
For M68HC05 and M1468HC05 compatibility, the H register is not
stacked.
stacked.