MC68HC05P4A Datasheet, PDF (20/72 Pages) Advanced Analogic Technologies – Microcontrollers

Memory Map
2.2 ROM
The user ROM consists of 48 bytes of page zero ROM from $0020 to $004F, 4096 bytes of ROM from
$0100 to $10FF, and 16 bytes of user vectors from $1FF0 to $1FFF. The self-check ROM and vectors
are located from $1F00 to $1FEF.
2.3 ROM Security Feature
A security feature⁽¹⁾ has been incorporated into the MC68HC05P4A to help prevent external reading of
code in the ROM. Placing unique customer code at ROM locations $0028–$002F aids in keeping
customer developed software proprietary.
2.4 RAM
The user RAM consists of 176 bytes of a shared stack area. The stack begins at address $00FF. The
stack pointer can access 64 bytes of RAM in the range $00FF to $00C0.
NOTE
Using the stack area for data storage or temporary work locations requires
care to prevent it from being overwritten due to stacking from an interrupt
or subroutine call.
1. No security feature is absolutely secure. However, Freescale’s strategy is to make reading or copying the ROM difficult for
unauthorized users.
MC68HC05P4A Data Sheet, Rev. 7.1
20
Freescale Semiconductor