at89c4051-12sa ATMEL Corporation, at89c4051-12sa Datasheet - Page 4

• Manufacturer Part Number: at89c4051-12sa
• Description: 8-bit Microcontroller With 4k Bytes Flash
• Manufacturer: ATMEL Corporation

Special Function Registers
A map of the on-chip memory area called the Special Func-
tion Register (SFR) space is shown in the table below.
Note that not all of the addresses are occupied, and unoc-
cupied addresses may not be implemented on the chip.
Read accesses to these addresses will in general return
random data, and write accesses will have an indetermi-
nate effect.
Table 1. AT89C4051 SFR Map and Reset Values
4
0D8H
0D0H
0C8H
0C0H
0E8H
0E0H
0B8H
0B0H
0A8H
0A0H
0F8H
0F0H
98H
90H
88H
80H
XXX00000
0XX00000
00000000
00000000
00000000
11111111
00000000
11111111
00000000
SCON
TCON
PSW
ACC
P3
P1
IP
IE
B
XXXXXXXX
AT89C4051
00000000
00000111
TMOD
SBUF
SP
00000000
00000000
DPL
TL0
00000000
00000000
DPH
TL1
User software should not write 1s to these unlisted loca-
tions, 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.
00000000
TH0
00000000
TH1
0XXX0000
PCON
0FFH
0F7H
0EFH
0E7H
0DFH
0D7H
0CFH
0C7H
0BFH
0B7H
0AFH
0A7H
9FH
97H
8FH
87H