The XOR Gate

The XOR gate (pronounced "exclusive OR") is an important logic gate that appears frequently in GCSE Computer Science exams. It is similar to the OR gate but with one key difference — the output is 1 only when the inputs are different.

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How the XOR Gate Works

XOR stands for Exclusive OR. For a two-input XOR gate:

• The output is 1 when the inputs are different (one is 0 and the other is 1).
• The output is 0 when the inputs are the same (both 0 or both 1).

The crucial difference between OR and XOR is what happens when both inputs are 1:

• OR: 1 OR 1 = 1 (at least one input is true — output is true)
• XOR: 1 XOR 1 = 0 (both inputs are the same — output is false)

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Truth Table for XOR

Input A	Input B	Output (A ⊕ B)
0	0	0
0	1	1
1	0	1
1	1	0