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Digital Electronics
NUMBER SYSTEM
BINARY CODES
TYPES OF BINARY CODES
BCD CODE
EFFICIENCY OF BCD
EXCESS-3 CODE
GRAY CODE
M out of N CODING SCHEME with EFFICIENCY
PARITY BIT
ERROR DETECTION by PARITY
QUESTION
HAMMING CODE (General form)
Relation of PARITY BIT with MESSAGE BITS
ILLUSTRATION-I
ILLUSTRATION-II
BOOLEAN ALGEBRA
K MAPS
COMBINATIONAL CKT
SEQUENTIAL CIRCUITS
TIMING CIRCUITS

 

 

Parity bit:

A parity bit is an extra bit that is attached to the information that is being sent from one position to the other. This bit is attached just to detect the error if any in the information during the transmission.  This bit is used to make number of 1’s in the message or information either even or odd. So if there is any change in any bit during transmission then there would be change in number of 1’s hence error would change the number of 1’s from odd to even or even to odd which can be detected. This way parity bit helps to detects errors.  So whenever we need to send information we’ll pass the information firstly through PARITY GENERATOR CIRCUIT and then send. Also at the receiver end information received is passed trough the PARITY CHECK CIRCUIT and if parity matches, only then we use the information. If we make number of 1’s even then it is called even parity and if number of 1’s is made odd then it is called odd parity.

But there are few drawbacks attached with this method:

    • This system can detect only odd combinations of error, not even combinations. That means if there is 2 or 4 or 6 etc number of then it would go undetected while it can easily detect 1, 3, 5 etc number of errors.
    • We can not check the position of error even if we are able to detect it.

     

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