MC68HC08AZ0 Datasheet, PDF (37/444 Pages) Motorola, Inc – Advance Information

Freescale Semiconductor, Inc.
RAM
RAM
Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Introduction
This section describes the 1024 bytes of RAM.
Functional description
Addresses $0050 through $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 64K byte memory space.
NOTE: For correct operation, the stack pointer must point only to RAM
locations.
Within page zero there are 176 bytes of RAM. Because the location of
the stack RAM is programmable, all page zero RAM locations can be
used for 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 efficiently access all page zero RAM locations. Page
zero RAM, therefore, provides an ideal location for frequently accessed
global variables.
Before processing an interrupt, the CPU uses 5 bytes of the stack to
save the contents of the CPU registers.
NOTE: For M6805 compatibility, the H register is not stacked.
1-ram
MOTOROLA
RAM
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MC68HC08AZ0
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