page_title: NOR gate
section_title: Hardware description and pinout
hierarchical_section_title: NOR gate / Hardware description and pinout
context_page_description: The NOR gate is a digital logic gate that implements logical NOR - it behaves according to the truth table to the right. A HIGH output results if both the inputs to the gate are LOW; if one or both input is HIGH, a LOW output results. NOR is the result of the negation of the OR operator. It can also in some senses be seen as the inverse of an AND gate. NOR is a functionally complete operation—NOR gates can be combined to generate any other logical function. It shares this property with the NAND gate. By contrast, the OR operator is monotonic as it can only change LOW to HIGH but not vice versa.
  In most, but not all, circuit implementations, the negation comes for free—including CMOS and TTL. In such logic families, OR is the more complicated operation; it may use a NOR followed by a NOT. A significant exception is some forms of the domino logic family.
  The original Apollo Guidance Computer used 4,100 integrated circuits, each one containing only two 3-input NOR gates.
context_section_description: NOR Gates are basic logic gates, and as such they are recognised in TTL and CMOS ICs. The standard, 4000 series, CMOS IC is the 4001, which includes four independent, two-input, NOR gates. The pinout diagram is as follows:
caption: Pinout Diagram of a 4001 Quad NOR DIP-format IC
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