NOR GATE
Outputs ON only when ALL inputs are OFF. The inverse of an OR gate. Built by feeding an OR gate through a NOT gate. Fundamental to RS NOR latches (memory circuits).
Truth Table
| Input A | Input B | Output |
|---|---|---|
| 0 (OFF) | 0 (OFF) | 1 (ON) |
| 0 (OFF) | 1 (ON) | 0 (OFF) |
| 1 (ON) | 0 (OFF) | 0 (OFF) |
| 1 (ON) | 1 (ON) | 0 (OFF) |
Overview: what the NOR Gate is and does
Outputs ON only when ALL inputs are OFF. The inverse of an OR gate. Built by feeding an OR gate through a NOT gate. Fundamental to RS NOR latches (memory circuits).
In plain terms, the output is on only when every input is off. NOR is OR followed by inversion, and because two cross-coupled NOR gates form the RS latch, it is the gate that makes redstone memory possible.
This page describes the gate as it behaves in Java Edition 1.21; the truth table and timings below match vanilla redstone exactly.
How it works: the redstone mechanics
Across its four input combinations the output is on in 1 case — A off with B off — and off in the remaining 3.
Expressed as boolean algebra that is output = NOT (A OR B).
A single-block NOR (inputs into a block, torch on the output face) adds 1 redstone tick.
Because redstone signals are just on or off, "on" here means a powered line (signal 1-15) and "off" means an unpowered line (signal 0); the gate cares only about presence or absence of power, not its exact strength.
How to build it
- 1Run input A and input B into the same solid block using redstone dust.
- 2Place a redstone torch on the output side of that block.
- 3The torch turns OFF when any input powers the block.
- 4Output is ON only when both inputs are OFF.
- 5This is the basis for the RS NOR latch memory circuit.
- 6Verify it against the truth table: setting the inputs to OFF and OFF should drive the output ON. Walk through every input combination once to confirm the gate matches the table above.
Uses & applications
- ▸NOR is OR followed by inversion, and because two cross-coupled NOR gates form the RS latch, it is the gate that makes redstone memory possible.
- ▸Single-block NOR (two inputs into block, torch on top) — a practical build choice for this gate.
- ▸Wall-mounted NOR (torch on side of block) — a practical build choice for this gate.
- ▸RS NOR latch (two cross-coupled NOR gates for memory) — a practical build choice for this gate.
Tips & common mistakes
- !Keep your inputs isolated with repeaters if signals are flowing back into each other; uncontrolled backflow between dust lines is the most common reason a gate reads the wrong value.
- !Remember the propagation cost: A single-block NOR (inputs into a block, torch on the output face) adds 1 redstone tick. If you chain several gates, those ticks add up and can desynchronise a fast circuit.
- !When a multi-gate circuit misbehaves, test each gate in isolation against its own truth table before assuming the wiring between them is at fault.
NOR Gate FAQ
What does a NOR Gate do in Minecraft?
A NOR Gate outputs a signal where the output is on only when every input is off. In boolean terms, output = NOT (A OR B).
What is the truth table of a NOR Gate?
Across its four input combinations the output is on in 1 case — A off with B off — and off in the remaining 3. The boolean expression is output = NOT (A OR B).
How do you build a NOR Gate with redstone?
Run input A and input B into the same solid block using redstone dust. Place a redstone torch on the output side of that block. Common variants include single-block NOR (two inputs into block, torch on top) and wall-mounted NOR (torch on side of block).
How much delay does a NOR Gate add?
A single-block NOR (inputs into a block, torch on the output face) adds 1 redstone tick. That matters most in clocks and adders where every redstone tick counts.