Cambridge O Level Computer Science · Syllabus 2210 · Boolean Logic
AND Gate
What is AND Gate?
A two-input logic gate whose output is 1 only when both inputs are 1 and 0 in every other case; its symbol is a D shape with a flat back and a semicircular nose, and it is written X = A AND B.
This definition is part of the Boolean Logic chapter in Cambridge O Level Computer Science.
Common mistakes with AND Gate
- “Any gate can be given three inputs if the question needs it.”ActuallyAll gates except NOT are limited to two inputs. There is no three-input symbol in section 4 of the syllabus.The fixCascade. Three conditions ANDed together take two AND gates; four take three.
Examiner tips on AND Gate
- Read the limits as instructions, not as background. “Circuits must be drawn for the statement given, without simplification” is not a hint about how examiners mark — it is the mark scheme. If the expression says NOT (A AND B), the circuit has an AND gate followed by a NOT gate. Replacing the pair with a single NAND gate changes the structure, and the structure is what is being assessed.
- Where the brackets go is not arbitrary. ((NOT A) AND B) AND C and (NOT A) AND (B AND C) give the same output on every row, and both are two AND gates. Either is acceptable as an expression — but whichever you write is the circuit you must then draw. Write it once, bracket it fully, and draw exactly that.
Reviewed by Academiq Edu Instructor PanelLast reviewed Syllabus 2026-2028