The NOR gate output is only 1 if neither input A NOR input B is 1.
Two more logic gates (Fig. 45.23) are useful in processing inputs. The AND gate
does just as the name implies.
The output of an AND gate is 1 only if inputs A AND Bare 1.
The NAND gate is the inverse of the AND.
The NAND gate output is 1 unless both its inputs are 1