Project 89
Neither This NOR That
Project 90
NOT This AND That
This circuit is commonly called a NOR gate. NOR
gates are used in digital logic circuits to perform
an inverted logical add. When one of the inputs is
high (one of the switches is on) the output is low
(LED off). The output will only be high (LED on) if
both inputs are low (both switches are off).
Build the circuit at left and test the combinations of the slide switch (S1)
and press switch (S2). If you compare it to the OR circuit in Project #82,
you can see the color LED (D8) lights in the opposite combinations of
that circuit. Hence, we refer to it as a NOR circuit (short for “NOT this
OR that”). Like the OR and AND, it is an important building block in
computers.
This circuit is commonly called a NAND gate.
NAND gates are used in digital logic circuits to
perform an inverted logical multiply. When one of
the inputs is low (one of the switches is off) the
output is high (LED on). The output will only be
low (LED off) if both inputs are high (both switches
are on).
Build the circuit at left and test the combinations of the slide switch (S1)
and press switch (S2). If you compare it to the AND circuit in Project
#83, you can see the color LED (D8) lights in the opposite combinations
of that circuit. Hence, we refer to it as a NAND circuit (short for “NOT
this AND that”). This circuit can also have more or less than two inputs,
though when it only has one input it is referred to as a NOT circuit. Like
the OR, AND, and NOR, NAND and NOT are important building blocks
in computers.
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