Hardware manual

Common Features Description
Atmel 8051 Microcontrollers Hardware Manual 2-19
4316A–8051–01/04
Note: Reserved
User software should not write to the reserved locations, since they may be used in
derivative Atmel 8051 products to invoke new features. The functions of the SFRs are
described as below.
2.2.1 Accumulator ACC is the Accumulator register. The mnemonics for accumulator-specific instructions,
however, refer to the accumulator simply as A.
2.2.2 B Register The B register is used during multiply and divide operations. For other instructions it can
be treated as another scratch pad register.
2.2.3 Program Status
Word
The PSW register contains program status information as detailed in Table 2-2.
Table 2-1. SFR Map
Bit
Addressable
8 Bytes
Non-bit Addressable
F8h
FFh
F0h B
F7h
E8h
EFh
E0h ACC
E7h
D8h
DFh
D0h PSW
D7h
C8h (T2CON)
(RCAP2L) (RCAP2H) (TL2) (TH2) CFh
C0h
C7h
B8h IP
BFh
B0h P3
B7h
A8h IE
AFh
A0h P2
A7h
98h SCON SBUF
9Fh
90h P1
97h
88h TCON TMOD TL0 TL1 TH0 TH1 AUXR CKCON 8Fh
80h P0 SP DPL DPH
PCON 87h
0/8 1/9 2/A 3/B 4/C 5/D 6/E 7/F