Logic Gates (Cambridge (CIE) A Level Computer Science) : Revision Note

(A AND B)

Returns TRUE only if both inputs are TRUE 

TRUE AND TRUE = TRUE

Otherwise = FALSE

(A OR B)

Returns TRUE if either input is TRUE 

TRUE OR FALSE = TRUE 

FALSE OR FALSE = FALSE

(NOT A)

Reverses the input value

NOT TRUE = FALSE

NOT FALSE = TRUE

(A XOR B)

Returns TRUE if either input is TRUE but NOT both

TRUE OR FALSE = TRUE 

FALSE OR FALSE = FALSE

TRUE OR TRUE = FALSE

(A NAND B)

Returns TRUE if either or both inputs are FALSE

TRUE OR FALSE = TRUE

FALSE OR FALSE = TRUE

TRUE OR TRUE = FALSE

(A NOR B)

Returns TRUE if both inputs are FALSE

TRUE OR FALSE = FALSE

FALSE OR FALSE = TRUE

TRUE OR TRUE = FALSE