PSW (Program Status Word) : 


It is a flag register. It provides four math flags and five control flags. Many Instructions affect several status flags, which are grouped together to form PSW.

CY: (Carry Flag)

It is a carry flag. Internal hardware or software sets It. It is set when there is a carry from D, bit. It is used in arithmetic, logical, jump, rotate and Boolean operations. In Boolean operation, it functions as an accumulator

AC: (Auxillary Carry Flag)

It is also called half carry. It is used in BCD arithmetic operations. It will be set
when there is a carry from D, bit

F0 : (User Flag 0)

It is user-defined flag. The user defines the function of this flag. The user can test, clear and set this flag through software.

RS1 and RSO: (Register Bank Select)

These flags are used to select only one bank of 8 registers. In default mode, it selects banko. The user can use only one bank of registers at a time. The programmer can use different banks for different programs.


OV: (Overflow Flag)

It is used in signed arithmetic operations only. It is used to detect overflow in the signed arithmetic operations

P : (Parity Flag)

It is a party flag. It shows the parity of data stored in the accumulator. If the number of 1s present in the accumulator is odd, then P flag is set to 1. This flag is reset for even number of is present in the accumulator. The parity of the data Including parity bit is always even. Hence, this flag can be used as even parity flag.