- A parity or check bit is a single bit added to a binary data.Parity bit is added at the end of the binary data.
- The main purpose of adding parity bit to the binary data is " Error Detection " in transmission.
Parity Bit Types :
Even Parity Bit :
- When we using the Even parity, we set the Parity bit 1 if binary data contains odd number of 1's.
- And set the parity bit to 0 if binary data contains the even number of 1's.
Odd Parity Bit :
- When we using the Odd parity, we set the Parity bit 0 if binary data contains odd number of 1's.
- And set the parity bit to 1 if binary data contains the even number of 1's.
| 7 bits of binary data | (count of 1's in binary data) | 8 bits including parity bit | |
|---|---|---|---|
| Even Parity | Odd Parity | ||
| 0000000 | 0 | 00000000 | 00000001 |
| 1000110 | 3 | 10001101 | 10001100 |
| 1011001 | 4 | 10110010 | 10110011 |
| 1111111 | 7 | 11111111 | 11111110 |
Why we need Parity bit ?
- When we transfer the digital data from one place to the other place can result in transmission errors.The receiver not receiving the same signal as transmitted by the transmitter as a result of electrical noise in the transmission process.
- If receiver want to know the received data is correct or not.At that time he will use the parity checksum.
Advantages of parity bit :
- Parity bit used for error detection in transmitted binary data.
- It also used to check the errors on memory devices.
Disadvantages of Parity bit :
- Not capable of finding all errors. Only errors which cause an odd number of bits to flip will be detected.
- No way to find which bit is false.
- Not able to correct the data so the data has to be retransmitted.
