ITPEC FE Morning April 2021 Question 6

Parity Check (Vertical Parity) — detect 1-bit transmission errors on a communication line.

A parity bit is added to make the total number of 1s either even or odd.

• •Can detect: single-bit errors (odd number of flipped bits)
• •Cannot detect: even number of bit errors (they cancel out)
• •Cannot correct: any errors — only detection, not correction

Why not others:
- (a) — parity check cannot correct errors at all; that requires Hamming code
- (c) — both odd and even parity detect 1-bit errors equally well
- (d) — neither odd nor even parity can detect an even number of bit errors; both detect only odd-count errors

Key rule: Parity check = detection only, 1-bit errors only. For correction → Hamming code. For multi-bit detection → CRC.

AI-generated — may contain errors