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PRELAB 7
BOOLEAN ALGEBRA  LOGIC GATES
KARNAUGH MAPS & COMBINATIONAL LOGIC
1. OBJECTIVES
s
Review the input/output logic of AND, OR, NOR, NAND and XOR gates.
s
Learn how to use Karnaugh’s maps to solve a given problem.
2. NOTATIONS
•
:
Logic AND
+
:
Logic OR
x
:
Logic XOR
‘
:
Logic NOR
3. BOOLEAN ALGEBRA
So far we have been building circuits using analog signals. In electric circuits, an analog signal is
an electric signal that can have several values (i.e. from 0 to 12 Volts including 2.50, 2.51, 3.2,
8.7, etc). On the other hand, a digital signal can only have certain values. Binary digital signals
can only have two values (usually 5 Volts or 0 Volts)
BINARY DIGITAL SIGNALS
ELECTRICAL
BOOLEAN
High
5 Volts
True (1)
Low
0 Volts
False (0)
It is also said that digital signals have
discrete values
. The Boolean algebra is the name given to
the mathematics associated with binary numbers (0 or 1). Logic functions (such as AND, OR,
NOT, etc) can be shown in the form of truth tables.
4. LOGIC GATES
Logic gates are electrical devices that perform logical functions using electrical inputs. Most of the
systems we use on a daily basis may be understood as combinational circuits using logic gates
that perform basic functions:
s
When using a washing machine, the washing cycle will only start if you selected the
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This note was uploaded on 09/18/2011 for the course ME 140L taught by Professor Staff during the Fall '09 term at University of Texas at Austin.
 Fall '09
 Staff

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