(1) Let's say we have a circuit from which we obtain a high when any input is low, and the
high output is used to activate another circuit or light a lamp.
(2) We probably would select a NOR gate with circles on the input rather than the NAND
symbol with a circle at the output even though they perform the same function. The reason is that we
usually select symbols that show the active output - in this case the high we need to activate a circuit or
light a lamp.