The 7427 IC contains three independent 3-Input NOR gates. Pins 7 and 14 supply power to all three gates within the chip. NOR gates, also known as inclusive NOR respond only if ALL of the input pins are logical zero. If any of the three inputs receives a high signal the state of the output pin will be logical zero (LOW).

This chip is similar in function to the 74LS02, which is the quad 2-input version of the NOR gate.