Intel 8XC251SA, User Manual

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8XC251SA, SB, SP, SQ USER’S MANUAL
3-14
Instructions in the MCS 51 architecture use the accumulator as the primary register for data
moves and calculations. However, in the MCS 251 architecture, any of registers R1–R15 can
serve for these tasks†. As a result, the accumulator does not play the central role that it has in
MCS 51 microcontrollers.
Figure 3-8. Dedicated Registers in the Register File and their Corresponding SFRs
† Bits in the PSW and PSW1 registers reflect the status of the accumulator. There are no equivalent status
indicators for the other registers.
R11, Accumulator, ACC
DR60 = Extended Stack Pointer, SPX
ACC
63 62 61 60
SPH SP
S:81H SP
Stack Pointer
Register File SFRs
SPH
Stack Pointer, High
S:BEH
DR56 = Extended Data Pointer, DPX
59 58 57 56
DPH
DPL DPXL
S:82H
DPL
Data Pointer, Low
DPH
Data Pointer Extended, Low
Data Pointer, High
S:83H
DPXL
R10, B Register
B
ACC
B
S:F0H
S:E0H
S:84H
A4152-02
i_mempar.fm5 Page 14 Thursday, June 27, 1996 2:06 PM