IC80C51
IC80C31
Table 2. Special Function Registers
Symbol
Description
Direct Address
Bit Address, Symbol, or Alternative Port Function
Reset Value
ACC(1)
B(1)
Accumulator
B register
E0H
F0H
83H
82H
E7
F7
E6
F6
E5
F5
E4
F4
E3
F3
E2
F2
E1
F1
E0
F0
00H
00H
00H
00H
DPH
DPL
Data pointer (DPTR) high
Data pointer (DPTR) low
AF
AE
AD
AC
AB
AA
A9
A8
IE(1)
IP(1)
P0(1)
Interrupt enable
Interrupt priority
Port 0
A8H
B8H
80H
EA
—
—
ES
ET1
EX1 ET0 EX0
BA B9 B8
PX1 PT0 PX0
82 81 80
0XX00000B
XXX00000B
FFH
BF
BE
BD
BC
BB
—
—
—
PS
PT1
87
86
85
84
83
P0.7 P0.6
AD7 AD6
P0.5 P0.4 P0.3 P0.2 P0.1 P0.0
AD5 AD4 AD3 AD2 AD1 AD0
97
96
95
94
93
92
91
90
P1(1)
P2(1)
Port 1
Port 2
90H
A0H
P1.7 P1.6
P1.5 P1.4 P1.3 P1.2 P1.1 P1.0
FFH
FFH
—
—
—
—
—
—
—
—
A7
A6
A5
A4
A3
A2
A1
A0
P2.7 P2.6
AD15 AD14 AD13 AD12 AD11 AD10 AD9 AD8
B7 B6 B5 B4 B3 B2 B1 B0
P3.7 P3.6 P3.5 P3.4 P3.3 P3.2 P3.1 P3.0
P2.5 P2.4 P2.3 P2.2 P2.1 P2.0
P3(1)
Port 3
B0H
87H
FFH
RD
WR
T1
T0
INT1 INT0 TXD RXD
PCON
Power control
SMOD
—
—
—
GF1 GF0 PD
IDL
0XXX0000B
D7
D6
D5
D4
D3
D2
D1
D0
PSW(1)
SBUF
Program status word
Serial data buffer
D0H
99H
CY
AC
F0
RS1 RS0
OV
—
P
00H
XXXXXXXXB
9F
9E
9D
9C
9B
9A
99
98
SCON(1)
SP
Serial controller
Stack pointer
98H
81H
SM0 SM1
SM2 REN TB8 RB8
TI
RI
00H
07H
8F
8E
8D
8C
8B
8A
89
88
TCON(1)
TMOD
TH0
Timer control
Timer mode
Timer high 0
Timer high 1
Timer low 0
Timer low 1
88H
89H
8CH
8DH
8AH
8BH
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
00H
00H
00H
00H
00H
00H
GATE C/T
M1
M0 GATE C/T
M1
M0
TH1
TL0
TL1
Notes:
1. Denotes bit addressable.
S3-10
Integrated Circuit Solution Inc.
MC001-0B
ICSI [ INTEGRATED CIRCUIT SOLUTION INC ]
