Logic Gates :)

What is a logic gate? 

• A logic gate is a device that performs a Boolean function (a function where the input(s) and outputs are 1 or 0 / true or false).
• Logic gates are used in electronic circuits and most of them have 2 inputs and 1 output.
• Truth tables are used to show every possible combination of inputs and their corresponding outputs for a logic gate/circuit.
• The logic gates on the OCR A Level Computer Science specification are: AND, OR, NOT & XOR

AND gate

left to right: logic gate diagram, OCR exam notation, javascript notation

• 2 binary inputs, 1 binary output
• Outputs 1 only if both inputs are 1, otherwise outputs 0

OR gate

left to right: logic gate diagram, OCR exam notation, javascript notation

• 2 binary inputs, 1 binary output
• Outputs 1 if one or both of the two inputs are 1, otherwise outputs 0

NOT gate

left to right: logic gate diagram, OCR exam notation, javascript notation

• 1 binary input, 1 binary output
• Outputs the opposite value to the input (0 → 1, 1 → 0)

XOR gate

left to right: logic gate diagram, OCR exam notation

• 2 binary inputs, 1 binary output
• XOR is the shorthand for "exclusive OR"
• Outputs 1 only if one of the inputs is 1 and the other is 0, otherwise outputs 0

Beyond the OCR spec:

NAND gate:

• 2 binary inputs, 1 binary output
• NAND is shorthand for NOT AND
• Outputs the logical inverse of an AND gate (Outputs 0 only if both inputs are 1, otherwise outputs 1)

NOR gate

• 2 binary inputs, 1 binary output
• NOR is shorthand for NOT OR
• Outputs the logical inverse of an OR gate (Outputs 0 if one or both of the inputs are 1, otherwise outputs 1)

Interactive truth tables!

NOT gate:

Other gates:

• Click buttons to reveal outputs for each logic gate :)