Even parity rule in digital communications: “In even parity, the sum (count) of 1-bits in the code group must be even.” Determine if this definition is accurate and complete.

Introduction / Context:
Parity bits provide a simple, low-cost method to detect single-bit errors during storage or transmission. The question checks knowledge of the precise rule that defines even parity and how the parity bit relates to the data bits.

Given Data / Assumptions:

• A “code group” is the set of data bits plus, when present, a parity bit.
• Even parity aims for an even count of logic 1s across the group after adding the parity bit.
• Scope includes serial links (UART), memory systems, and simple buses where parity may be used.

Concept / Approach:
Parity enforces a constraint on the count of 1s. With even parity, the transmitter sets the parity bit so that the total number of 1s in data + parity is even. At the receiver, the same count is performed; a mismatch indicates an odd number of flipped bits (most notably a single-bit error).

Step-by-Step Solution:

Verification / Alternative check:
Worked example: data 1011001 has four 1s (even). Even parity bit = 0; total remains even. If noise flips one bit, total becomes odd; error is detected. If two bits flip, parity may miss it (even number of errors).

Why Other Options Are Wrong:

• Incorrect: The definition provided is the standard rule.
• Applies only to 7-bit ASCII or odd parity: Parity rules are independent of the particular payload width and parity selection (odd/even).
• Depends on stop bits: Stop bits are UART framing parameters separate from parity logic.

Common Pitfalls:
Confusing parity with checksums/CRCs; assuming parity guarantees multi-bit error detection (it does not); mixing up the direction (even vs. odd).

Final Answer:
Correct