Students, you have to write this experiment in your RECORD.
EXPERIMENT:
1 LOGIC GATES
AIM:- To study and verify
the truth table of logic gates
LEARNING
OBJECTIVE:-
Identify various ICs
and their specification.
COMPONENTS
REQUIRED:-
Logic gates (IC)
trainer kit.
Connecting patch
chords.
IC 7400, IC 7408, IC
7432, IC 7406, IC 7402, IC 7404, IC 7486
THEORY:
The basic logic gates
are the building blocks of more complex logic circuits. These logic gates
perform the basic Boolean functions, such as AND, OR, NAND, NOR, Inversion, Exclusive-OR,
Exclusive-NOR. Fig. below shows the circuit symbol, Boolean function, and truth.
It is seen from the Fig that each gate has one or two binary inputs, A and B,
and one binary output, C. The small circle on the output of the circuit symbols
designates the logic complement. The AND, OR, NAND, and NOR gates can be
extended to have more than two inputs. A gate can be extended to have multiple
inputs if the binary operation it represents is commutative and associative. These
basic logic gates are implemented as small-scale integrated circuits (SSICs) or
as part of more complex medium scale (MSI) or very large-scale (VLSI)
integrated circuits. Digital IC gates are classified not only by their logic
operation, but also the specific logic-circuit family to which they belong.
Each logic family has its own basic electronic circuit upon which more complex
digital circuits and functions are developed. The following logic families are
the most frequently used.
TTL _Transistor-transistor logic
ECL _Emitter-coupled logic
MOS _Metal-oxide semiconductor
CMOS _Complementary metal-oxide semiconductor
TTL and ECL are based
upon bipolar transistors. TTL has a well established popularity among logic
families. ECL is used only in systems requiring high-speed operation. MOS and CMOS,
are based on field effect transistors. They are widely used in large scale
integrated circuits because of their high component density and relatively low
power consumption. CMOS logic consumes far less power than MOS logic. There are
various commercial integrated circuit chips available. TTL ICs are usually
distinguished by numerical designation as the 5400 and 7400 series.
AND gate
The AND gate is an electronic circuit that gives
a high output (1) only if all its inputs are
high. A dot (.) is used to show the AND operation i.e. A.B. Bear in
mind that this dot is sometimes omitted i.e. AB
OR gate
The OR gate is an
electronic circuit that gives a high output (1) if one or more of
its inputs are high. A plus (+) is used to show the OR operation.
The NOT gate is an electronic circuit that
produces an inverted version of the input at its output. It is also known
as an inverter. If the input variable is A, the inverted
output is known as NOT A. This is also shown as A', or A with a bar over
the top, as shown at the outputs. The diagrams below show two ways that the
NAND logic gate can be configured to produce a NOT gate. It can also be done
using NOR logic gates in the same way.
This is a NOT-AND gate
which is equal to an AND gate followed by a NOT gate. The outputs of all
NAND gates are high if any of the inputs are low. The symbol
is an AND gate with a small circle on the output. The small circle represents
inversion.
NOR gate
This is a NOT-OR gate which
is equal to an OR gate followed by a NOT gate. The outputs of all NOR
gates are low if any of the inputs are high.
The symbol is an OR gate with a small circle on
the output. The small circle represents inversion.
The 'Exclusive-OR'
gate is a circuit which will give a high output if either, but not both,
of its two inputs are high. An encircled plus sign (
) is used to show the Ex-OR
operation.
) is used to show the Ex-OR
operation.
The
'Exclusive-NOR' gate circuit does the opposite to the
Ex-OR gate. It will give a low output if either,
but not both, of its two inputs are high. The symbol is an EX-OR gate with
a small circle on the output. The small circle represents inversion.
PROCEDURE:
1. Check the
components for their working.
3. Make connections
as shown in the circuit diagram.
4. Provide the input data
via the input switches and observe the output on output LEDs.
RESULT:
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