A parity bit, or check bit, is
a bit added to the end of a string of binary
code that indicates whether the
number of bits in the string with the value one is even or odd.
There are two variants of parity bits: even parity bit and odd parity bit.
In case of even parity, the parity bit is set to 1 if the count of ones in a given set of bits (not including the parity bit) is odd, making the count of ones in the entire set of bits (including the parity bit) even.
When using odd parity, the parity bit is set to 1 if the count of ones in a given set of bits (not including the parity bit) is even, making the count of ones in the entire set of bits (including the parity bit) odd.
8051 Parity flag (PSW.0)
The parity flag reflects the number of 1 s
in the A (accumulator) register only. If the A register contains an odd number
of Is, then P = 1. Therefore, P = 0 if A has an even number of Is.
