MC68HC908GR8 Datasheet, PDF (27/286 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

Chapter 2
Memory Map
2.1 Introduction
The CPU08 can address 64K bytes of memory space. The memory map, shown in Figure 2-1, includes:
• 8K bytes of FLASH memory, 7680 bytes of user space on the MC68HC908GR8 or
4K bytes of FLASH memory, 4096 bytes of user space on the MC68HC908GR4
• 384 bytes of random-access memory (RAM)
• 36 bytes of user-defined vectors
• 310 bytes of monitor routines in read-only memory (ROM)
• 544 bytes of integrated FLASH burn-in routines in ROM
2.2 Unimplemented Memory Locations
Accessing an unimplemented location can cause an illegal address reset if illegal address resets are
enabled. In the memory map (Figure 2-1) and in register figures in this document, unimplemented
locations are shaded.
2.3 Reserved Memory Locations
Accessing a reserved location can have unpredictable effects on MCU operation. In the Figure 2-1 and
in register figures in this document, reserved locations are marked with the word Reserved or with the
letter R.
2.4 Input/Output (I/O) Section
Most of the control, status, and data registers are in the zero page area of $0000–$003F. Additional I/O
registers have these addresses:
• $FE00; SIM break status register, SBSR
• $FE01; SIM reset status register, SRSR
• $FE03; SIM break flag control register, SBFCR
• $FE04; interrupt status register 1, INT1
• $FE05; interrupt status register 2, INT2
• $FE06; interrupt status register 3, INT3
• $FE07; reserved FLASH test control register, FLTCR
• $FE08; FLASH control register, FLCR
• $FE09; break address register high, BRKH
• $FE0A; break address register low, BRKL
• $FE0B; break status and control register, BRKSCR
• $FE0C; LVI status register, LVISR
• $FF7E; FLASH block protect register, FLBPR
Data registers are shown in Figure 2-2, and Table 2-1 is a list of vector locations.
MC68HC908GR8 • MC68HC908GR4 Data Sheet, Rev. 7
Freescale Semiconductor
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