MC68HC05K0 Datasheet, PDF (37/154 Pages) Freescale Semiconductor, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Central Processor Unit (CPU)
CPU Registers
3.3.1 Accumulator
The accumulator (A) shown in Figure 3-2 is a general-purpose 8-bit
register. The accumulator holds operands and results of arithmetic and
non-arithmetic operations.
Bit 7
Read:
Write:
Reset:
6
5
4
3
2
Unaffected by reset
Figure 3-2. Accumulator (A)
1
Bit 0
3.3.2 Index Register
In the indexed addressing modes, the CPU uses the byte in the index
register (X) to determine the effective address of the operand. (See
10.3.5 Indexed, No Offset, 10.3.6 Indexed, 8-Bit Offset, 10.3.7
Indexed, 16-Bit Offset.) The 8-bit index register shown in Figure 3-3
can also serve as a temporary data storage location.
Bit 7
Read:
Write:
Reset:
6
5
4
3
2
Unaffected by reset
Figure 3-3. Index Register (X)
1
Bit 0
MC68HC05K0 • MC68HC05K1 — Rev. 2.0
Central Processor Unit (CPU)
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Technical Data