mc68hc05ct4fn Freescale Semiconductor, Inc, mc68hc05ct4fn Datasheet - Page 26

• Manufacturer Part Number: mc68hc05ct4fn
• Description: Mc68hc05 Family Of Microcontrollers Mcus
• Manufacturer: Freescale Semiconductor, Inc

Memory
2.5 ROM Security Feature
2.6 Random-Access Memory (RAM)
General Release Specification
NOTE:
Twelve of the user vectors, $1FF4–$1FFF, are dedicated to reset and
interrupt vectors. The four remaining locations — $1FF0, $1FF1, $1FF2,
and $1FF3 — are general-purpose user ROM locations.
A security feature has been incorporated into the MC68HC05CT4 to
help prevent external viewing of the ROM contents. This feature aids in
maintaining the security of proprietary information in customer-
developed software.
The user RAM consists of 256 bytes of a shared stack area. The RAM
starts at address $0030 and ends at address $012F. The stack begins
at address $00FF. The stack pointer can access 64 bytes of RAM in the
range $00FF to $00C0.
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, Motorola’s strategy is to make reading or
copying the ROM difficult for unauthorized users.
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
1
Memory
MC68HC05CT4
—
Rev. 2.0