MC68HC05P9ACDW FREESCALE [Freescale Semiconductor, Inc], MC68HC05P9ACDW Datasheet - Page 24

• Manufacturer Part Number: MC68HC05P9ACDW
• Description: HCMOS Microcontroller Unit
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Memory
RAM
ROM
ROM Security Feature
24
NOTE:
The 128 addresses from $0080–$00FF are RAM locations. The CPU
uses the top 64 RAM addresses, $00C0–$00FF, as the stack. Before
processing an interrupt, the CPU uses five bytes of the stack to save the
contents of the CPU registers. During a subroutine call, the CPU uses
two bytes of the stack to store the return address. The stack pointer
decrements when the CPU stores a byte on the stack and increments
when the CPU retrieves a byte from the stack.
Be careful when using nested subroutines or multiple interrupt levels.
The CPU may overwrite data in the RAM during a subroutine or during
the interrupt stacking operation.
The following addresses are mask programmable ROM locations:
A security
help prevent externally reading of code in the ROM. This feature aids in
keeping customer developed software proprietary.
1. No security feature is absolutely secure. However, Motorola’s strategy is to make reading or
copying the ROM difficult for unauthorized users.
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Freescale Semiconductor, Inc.
For More Information On This Product,
$0020–$004F
$0100–$08FF
$1FF8–$1FFF (reserved for user-defined interrupt and reset
vectors)
1
feature has been incorporated into the MC68HC05P9A to
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Memory
10-mc68hc05p9a
MOTOROLA