- It is also called as check bit.
- A bit added to binary code that indicates whether the number of 1 bits in string is even or odd.
- Parity bits are used as error detecting code.
- Parity bit applied to the smallest unit of a communication protocol.
- Parity bit checking is used for transmitting ASCII characters, which have 7 bits, leaving the 8th bit as a parity bit.
Types:
- Even Parity
- Odd Parity
Even Parity:
- Each byte should contain an even number of ones.
- If the count is odd then the parity bit value set to 1.
- If the count is already even then the parity bit value set to 0.
Odd Parity:
- Each byte should contain an odd number of ones.
- If the count is even then the parity bit value set to 1.
- If the count is already odd then the parity bit value set to 0.
Error Detection:
- An odd number of bits are transmitted incorrectly, the parity bit will be incorrect thus indicating that parity error occurred in the transmission.
- The parity bit only for detecting error, not correcting an errors.
- Error detection uses the concept of redundancy, adding extra bits for detecting error at the destination.
Usage:
- It is used for detecting the error in transmission code.
Drawbacks:
- Single parity bit check only can detect single bit, can not detect more than 1 bit.
