Accumulator – NEC PD750008 User Manual
Page 77
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CHAPTER 4 INTERNAL CPU FUNCTIONS
Figure 4-9. Register Pair Format
4.6 ACCUMULATOR
In the µPD750008, the A register and XA register pair function as accumulators. The A register is mainly
used for 4-bit data processing instructions, and the XA register pair is mainly used for 8-bit data processing
instructions.
For a bit manipulation instruction, the carry flag (CY) functions as a bit accumulator.
Figure 4-10. Accumulator
0
3
C
0
3
B
0
3
E
0
3
D
0
3
L
0
3
H
0
3
A
0
3
X
One bank
Bit accumulator
4-bit accumulator
8-bit accumulator
CY
A
A
X
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