Atmel AT89C2051 Manual page 5

6. Special Function Registers
Table 6-1. AT89C2051 SFR Map and Reset Values
0F8H
B
0F0H
00000000
0E8H
ACC
0E0H
00000000
0D8H
PSW
0D0H
00000000
0C8H
0C0H
IP
0B8H
XXX00000
P3
0B0H
11111111
IE
0A8H
0XX00000
0A0H
SCON
98H
00000000 XXXXXXXX
P1
90H
11111111
TCON
88H
00000000
80H
0368G–MICRO–6/05
A map of the on-chip memory area called the Special Function Register (SFR) space is shown in
the table below.
Note that not all of the addresses are occupied, and unoccupied addresses may not be imple-
mented on the chip. Read accesses to these addresses will in general return random data, and
write accesses will have an indeterminate effect.
User software should not write 1s to these unlisted locations, since they may be used in future
products to invoke new features. In that case, the reset or inactive values of the new bits will
always be 0.
SBUF
TMOD TL0
00000000 00000000
SP DPL
00000111 00000000
TL1 TH0
00000000 00000000
DPH
00000000
TH1
00000000
AT89C2051
0FFH
0F7H
0EFH
0E7H
0DFH
0D7H
0CFH
0C7H
0BFH
0B7H
0AFH
0A7H
9FH
97H
8FH
PCON
87H
0XXX0000
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