Parity/Non-parity Check Early transmission codes had a serious problem in that a bit could be lost or gained in transmission because of an electrical or mechanical failure/ If the loss went undetected, the character received on the other end of the To Prevent this from happening, a parity check system was developed. Each character is represented by a byte consisting of a combination of intelligence bits (seven bits in ASCII and eight bits in EBCDIC) and an additional bit called a check or parity bit. Even parity codes place a check bit with each byte that contains an uneven number of 1 bits.