The Program Status Word (PSW) is an 8-bit register that contains status flags in microprocessors like the 8085 and microcontrollers like the 8051. The PSW has an accumulator and flag register, with the accumulator being higher order and flag register lower order. The PSW tracks status flags like the carry, parity, auxiliary, zero, and sign flags to indicate results of operations such as carries/borrows between bits and whether a result is zero or negative.

1. PROGRAM STATUS WORD
(PSW)
By:- Sheetal Verma

2.  Program status word refers to the accumulator and
the flag register where accumulator is the high order
register and the flag register is the lower order
register.
 PSW is a 8 bit register.
 PSW will be in 8085 microprocessor and 8051
microcontroller.

4. Different Flags in PSW
Carry Flag
This flag is set whenever there has been a carry out of, or a borrow into, the
higher order bit of the result (8 bit).
Parity Flag
This flag is set when the result has even parity, an even number of 1 bit.

5. Auxiliary Flag
This flag is set, whenever there has been a carry out of the lower nibble into
the higher nibble or a borrow from higher nibble into the lower nibble of an 8
bit quantity, else AF is reset.
Zero Flag
This flag is set, when the result of the operation is zero else it is reset.
Sign Flag
This flag is set, when the MSB(most significant bit) of the result is 1.