Registers
Table 29. PSW Register
PSW (S:8Eh) – Program Status Word Register
7
6
5
4
3
2
1
0
CY
AC
F0
RS1
RS0
OV
F1
P
Bit
Bit
Number
Mnemonic Description
Carry Flag
Carry out from bit 1 of ALU operands.
7
CY
Auxiliary Carry Flag
Carry out from bit 1 of addition operands.
6
5
AC
F0
User Definable Flag 0
Register Bank Select Bits
Refer to Table 26 for bits description.
4 - 3
RS1:0
Overflow Flag
Overflow set by arithmetic operations.
2
1
OV
F1
User Definable Flag 1
Parity Bit
0
P
Set when ACC contains an odd number of 1’s.
Cleared when ACC contains an even number of 1’s.
Reset Value = 0000 0000b
28
AT8xC51SND2C
4341D–MP3–04/05