#073 4-input NOR Gate

Demonstrates building a 4-input NOR gate from 74LS02 NOR gates and an 74LS08 AND gate, with test automation using an Arduino.

Notes

See the LEAP#072 74LS02 Quad 2-input NOR gate test for more detail on the 74LS02.

This project demonstrates building a 4-input NOR gate from 74LS02 NOR gates and an 74LS08 AND gate.

Construction

Designed with Fritzing: see QuadNOR.fzz.

Setup on a breadboard for testing:

The Sketch

See QuadNOR.ino.

The sketch simply drives the A1, B1, A2, B2 lines through all 16 combinations.

Behaviour

Connected to a logic analyzer & scope for testing:

Here’s the trace confirming the behaviour:

• D0-D6: A1, B1, AB1, A2, B2, AB2, Y1
• D7: unused
• CH1 (Yellow): Y1

The resulting logic table:

Credits and References

• LEAP#072 74LS02 Quad 2-input NOR gate test
• 74LS02 datasheet
• 7400 series