MC908QY8CDWE Datasheet, PDF (25/232 Pages) Freescale Semiconductor, Inc – Addendum to MC68HC908QB8, rev. 3

Chapter 2
Memory
2.1 Introduction
The central processor unit (CPU08) can address 64 Kbytes of memory space. The memory map, shown
in Figure 2-1.
2.2 Unimplemented Memory Locations
Executing code from an unimplemented location will cause an illegal address reset. In Figure 2-1,
unimplemented locations are shaded.
2.3 Reserved Memory Locations
Accessing a reserved location can have unpredictable effects on MCU operation. In Figure 2-1, register
locations are marked with the word Reserved or with the letter R.
2.4 Direct Page Registers
Figure 2-2 shows the memory mapped registers of the MC68HC908QB8. Registers with addresses
between $0000 and $00FF are considered direct page registers and all instructions including those with
direct page addressing modes can access them. Registers between $0100 and $FFFF require non-direct
page addressing modes. See Chapter 7 Central Processor Unit (CPU) for more information on
addressing modes.
MC68HC908QB8 Data Sheet, Rev. 3
Freescale Semiconductor
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