Program status word(PSW)

Flags: 1 bit registers provided to store the status of results of some instruction : It is a flip flop8051 has :-4 math flags: Carry(CY), Auxiliary carry(AC), Overflow(OV), Parity(P)-3 general purpose user flag:1) Carry flag (CY) - Set when there is a carry or borrow out of the MSB (D7) of the result2)Auxiliary carry ( AC) -Set when there is a carry out from lower nibble to higher nibble or borrow from higher nibble to lower nibble3)Overflow flag(OV)-arithmetic overflow has occurred4)Parity flag(P)-the result has even parity (even no. of 1's)General purpose flags-can be set 1 or 0 as programmer desires-F0,GF0,GF! are the three general purpose flag-F0 is in PSW and GF0 and GF1 are in PCON register