Explain with example a block parity code

Block parity code is a type of error detection method used in digital communications to detect and correct errors. It works by adding an extra bit, called a parity bit, to the data being transmitted. This parity bit is used to ensure that the total number of 1-bits in the data (including the parity bit) is even (in the case of even parity) or odd (in the case of odd parity).

Let's take an example to understand this better:

Suppose we have a 7-bit ASCII code for a character, let's say 'A', which is 1000001 in binary.

If we are using even parity, we count the number of 1-bits in the data. In this case, there are two 1-bits. Since 2 is already an even number, we don't need to add a parity bit. So, the parity bit is 0 and the data transmitted is 10000010.

If we are using odd parity, we again count the number of 1-bits in the data. Since 2 is an even number and we want the total number of 1-bits to be odd, we add a parity bit of 1. So, the data transmitted is 10000011.

The receiver then counts the number of 1-bits in the received data. If the total number of 1-bits is not even (for even parity) or not odd (for odd parity), the receiver knows that there was an error during transmission.