16
Neither This NOR That
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
93, you can see the LED (D1) 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).
NOT This AND That
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
94, you can see the LED (D1) 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.
Project 95
Project 96
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).
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