Please enable JavaScript.
Coggle requires JavaScript to display documents.
2.4 Logic Gate and Logic Circuit 2.4.2 Logic Gate (A gate will have one…
2.4 Logic Gate and Logic Circuit
2.4.2 Logic Gate
Boolean Algebra and Truth Table set out the
basic principles of logic.
Any Boolean algebra operation can be
associated with a logic gate.
– AND operation AND gate
– OR operation OR gate
– NOT operation NOT gate
Gate is an electronic circuit in which the input
and output represent the statement of
Boolean algebra.
Five basic logic gates are:
– AND gate
– OR gate
– NOT gate
– NAND gate
– NOR gate
A gate will have one or more binary input of 0
or 1 but just one binary output.
AND gate - has two input and one output
OR gate - has two input and one output
NOT gate - has one input and one output
NAND gate - has two input and one output
NOR gate - has two input and one output
TRUTH TABLE
• A truth table is used to show the function of a
logic gate.
• It shows the output states for every possible
combination of input states.
• For a logic gate with n input, there are 2
n rows
in the truth table.
• Each row will represent different combination
of input states
Logic Gate: AND
The AND gate has two binary input and one
binary output
The AND gate produces a TRUE output if and
only if both A and B are TRUE.
The Boolean expression for AND gate can be
written in three ways:
Y = A • B, Y = AB, or Y = A ∩ B.
Gate AND produces TRUE only when all input are
TRUE.
Logic Gate: OR
The OR gate has two binary input and one
binary output.
The OR gate produces a TRUE output if either
A or B (or both) is TRUE.
The Boolean equation for an OR gate is
written as Y = A + B or Y = A ∪ B.
Gate OR produces TRUE when any of the input is
TRUE.
Logic Gate: NOT
The NOT gate has one binary input and one
binary output.
The output of NOT gate is the inverse of its
input. TRUE input will produce FALSE, and
FALSE input will produce TRUE.
The Boolean equation for NOT gate is written
as Y = A’
Logic Gate: NAND
Combination of AND and NOT gate.
NAND gate produce TRUE output when any of
the input is FALSE.
Produce FALSE output when all of the input
are TRUE.
The Boolean expression for NAND gate can be
written in three ways:
Y = A • B, Y = AB, or Y = A ∩ B.
Logic Gate: NOR
Combination of OR and NOT gate.
Produce TRUE output when all of the input
are FALSE.
Produce FALSE output when any of the input
is TRUE.
The Boolean equation for an NOR gate is
written as Y = A + B or Y = A ∪ B