CHAPTER 3 COMBINATIONAL LOGIC
Basic Combinational Logic Circuits AND-OR LOGIC
A B
X=AB+CD
C D
A B C
& ≥1 &
D
AND-OR-INVERT LOGIC
A B C D
X=AB+CD
A B C D
& ≥1 &
Basic Combinational Logic Circuits
Exclusive-ORLogic
A
X = AB + AB B
A B
A B
=1
X
Basic Combinational Logic Circuits
Exclusive-NOR Logic
A
X = AB + AB B
A B
X = AB + AB
Implementing Combinational Logic
From Boolean Expression to a Logic Circuit
It’s usually best to reduce a circuit to its SOP form
From a Truth Table to a Logic Circuit
Universal Property of NAND & NOR Gates
IC are packaged with a 4 gates per chip, buy only NAND IC and save a lots of money on inventory. One type of chip for all logic applications.
Universal Property of NAND & NOR Gates
NAND gates as a Universal Logic Element: =
A
A B
=
A
= B
Universal Property of NAND & NOR Gates
NOR gates as a Universal Logic Element: A A B A B
= = =