Combinational Logic
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Transcript Combinational Logic
Combinational Logic
Weiqiang Sun
A brief review
Logic gates
AND, OR, NOT
NAND, NOR, XOR, XNOR
Boolean algebra
Rules and axioms
Analysis of logic circuits
DeMorgan’s Theorem
Standard forms of Boolean expressions
K-Map
A brief review –
continued…
Functions of combinational logic
Adders
Comparators
Decoders
Encoders
Code converters
Multiplexers
Parity Generator/checkers
Problem
With logic gates, design a logic circuit to check whether
the blood plasma type of the donor is compatible with
that of the recipient.
Repeat the previous problem with the blood
compatibility table below.
Problem
Implement a full subtractor with logic gates.
Problem
Repeat the problem with 3-line to 8-line decoders and
NAND gates.
Problem
Design a logic circuit that converts BCD to excess-3
codes
Problem
Repeat the previous problem with a 4-line to 16-line
decoder and necessary gates
Problem
Repeat the problem with 1-out-of-16 multiplexers
(data selector).
Problem
Repeat the problem with 1-out-of-8 multiplexers
(data selector).
Homework
1. Design a 5-line to 32-line decoder with 74LS138
and 74LS139.
2. Implement the following logic function with
74LS138 and NAND gate
a.
b.
F=ΣX,Y,Z(2,4,7),
F=ΣA,B,C,D(2,4,6,14)
3. Repeat problem 2 with 74X151