MC908KX2MDWE Datasheet, PDF (197/210 Pages) Freescale Semiconductor, Inc – High-performance M68HC08 architecture, Fully upward-compatible object code with M6805, M146805, and M68HC05 Families

Appendix B
MC68HC08KX8
B.1 Introduction
This appendix describes the differences between the read-only memory (ROM) version (MC68HC08KX8)
and the FLASH version (MC68HC908KX8) of the microcontroller.
Basically, the differences are:
• FLASH x ROM module changes
– FLASH for ROM substitution
– Partial use of FLASH-related module
• Configuration register programming
• Wider range of operating voltage
B.2 FLASH x ROM Module Changes
This subsection describes changes between the FLASH and ROM modules.
B.2.1 FLASH for ROM Substitution
FLASH memory and FLASH supporting modules are replaced by ROM memory, see Figure B-1.
In Figure B-1, the user FLASH and user FLASH vector space are respectively substituted by user ROM
and user ROM vector space.
Additionally, these modules and registers have been eliminated in the ROM version:
• FLASH burn-in ROM module — Auxiliary FLASH routine codes
• FLASH charge pump module — High-voltage for FLASH programming
• MENRST module — Helps erased FLASH parts programming, see 13.3.1.5 Forced Monitor Mode
Entry Reset (MENRST)
• SIM reset status register, bit 2 — Refers to MENRST. See 13.7.1 SIM Reset Status Register.
MENRST has no function in the ROM version and reading this bit will return 0.
• FLASH test control register, FLTCR
• FLASH control register, FLCR
• FLASH block protect register, FLBPR
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 Data Sheet, Rev. 2.1
Freescale Semiconductor
197