Rainbow Electronics AT89C51SND1C - Manual (Page 28)

28
AT8xC51SND1C
4109E–8051–06/03
Registers Table 28. PSW Register
PSW (S:8Eh) – Program Status Word Register
Reset Value = 0000 0000b
7 6 5 4 3 2 1 0
CY AC F0 RS1 RS0 OV F1 P
Bit
Number
Bit
Mnemonic Description
7 CY
Carry Flag
Carry out from bit 1 of ALU operands.
6 AC
Auxiliary Carry Flag
Carry out from bit 1 of addition operands.
5 F0 User Definable Flag 0
4 - 3 RS1:0
Register Bank Select Bits
Refer to Table 25 for bits description.
2 OV
Overflow Flag
Overflow set by arithmetic operations.
1 F1 User Definable Flag 1
0 P
Parity Bit
Set when ACC contains an odd number of 1’s.
Cleared when ACC contains an even number of 1’s.