mc68hc908qb4 Freescale Semiconductor, Inc, mc68hc908qb4 Datasheet - Page 23

• Manufacturer Part Number: mc68hc908qb4
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

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. 2
Freescale Semiconductor
23