The Digital Logic Level

FloydFloydDigital Fundamentals, 9/eDigital Fundamentals, 9/e

Copyright ©2006 by Pearson Education, Inc.Copyright ©2006 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458Upper Saddle River, New Jersey 07458

All rights reserved.All rights reserved.Slide 1

The Digital Logic LevelThe Digital Logic Level

Ass Prof Dr. Masri Ayob




Digital and Analog Quantities Digital and Analog Quantities

• Analog quantities have continuous Analog quantities have continuous valuesvalues

• Digital quantities have discrete sets of Digital quantities have discrete sets of valuesvalues




Digital and Analog QuantitiesDigital and Analog Quantities

Analog quantitiesAnalog quantities have have continuous valuescontinuous values Digital quantitiesDigital quantities have have

discrete sets of valuesdiscrete sets of values




Digital and Analog QuantitiesDigital and Analog Quantities

Types of electronic devices or instruments:Types of electronic devices or instruments:• AnalogAnalog• DigitalDigital• Combination analog and digitalCombination analog and digital




Binary Digits, Logic Levels, and Digital Waveforms Binary Digits, Logic Levels, and Digital Waveforms

• The conventional numbering system The conventional numbering system uses ten digits: 0,1,2,3,4,5,6,7,8, and 9.uses ten digits: 0,1,2,3,4,5,6,7,8, and 9.

• The binary numbering system uses just The binary numbering system uses just two digits: two digits: 00 and and 1.1.





• The two binary digits are designated The two binary digits are designated 00 and and 11

• They can also be called LOW and HIGH, They can also be called LOW and HIGH, where where LOW = 0LOW = 0 and and HIGH = 1HIGH = 1





Binary values are also Binary values are also represented by voltage levelsrepresented by voltage levels





• ttww = pulse width = pulse width• T = period of the waveformT = period of the waveform• f = frequency of the waveformf = frequency of the waveform

T1f




Basic Logic Operations Basic Logic Operations

There are only three basic logic operations:There are only three basic logic operations:




GatesGates

(a) A transistor inverter. (b) A NAND gate.(a) A transistor inverter. (b) A NAND gate.(c) A NOR gate.(c) A NOR gate.




Overview of Basic Logic Functions Overview of Basic Logic Functions

• Comparison functionComparison function• Decoding functionDecoding function• Counting functionCounting function• Arithmetic functionsArithmetic functions• Code conversion functionCode conversion function• Encoding functionEncoding function• Data selection functionData selection function• Data storage functionData storage function





• Comparison functionComparison function– Compares two binary values and Compares two binary values and

determines whether or not they are equaldetermines whether or not they are equal• Decoding functionDecoding function

– Converts binary-coded information into a Converts binary-coded information into a non-binary formnon-binary form

• Counting functionCounting function– Generates sequences of digital pulse that Generates sequences of digital pulse that

represent numbers represent numbers





• Arithmetic functionsArithmetic functions– Perform the basic arithmetic Perform the basic arithmetic

operations on two binary values:operations on two binary values:• AdditionAddition• Subtraction of two valuesSubtraction of two values• MultiplicationMultiplication• DivisionDivision





• Code conversion functionCode conversion function– Converts, or translates, information Converts, or translates, information

from one code format to another.from one code format to another.• Encoding functionEncoding function

– Converts non-binary information Converts non-binary information into a binary codeinto a binary code





• Data selection functionData selection function– Multiplexer (mux)Multiplexer (mux)

• Switches digital data from any number of Switches digital data from any number of input sources to a single output lineinput sources to a single output line

• Demultiplexer (demux)Demultiplexer (demux)– switches digital data from a single switches digital data from a single

input to any number of output linesinput to any number of output lines





• Data storage functionData storage function– Retains binary data for a period of Retains binary data for a period of

timetime• Flip-flops (bistable multvibrators)Flip-flops (bistable multvibrators)• RegistersRegisters• Semiconductor memoriesSemiconductor memories• Magnetic-media memoriesMagnetic-media memories• Optical-media memoriesOptical-media memories




Fixed-Function Integrated Circuits Fixed-Function Integrated Circuits

IC package stylesIC package styles• Dual in-line package (DIP)Dual in-line package (DIP)• Small-outline IC (SOIC)Small-outline IC (SOIC)• Flat pack (FP)Flat pack (FP)• Plastic-leaded chip carrier (PLCC)Plastic-leaded chip carrier (PLCC)• Leadless-ceramic chip carrier (LCCC)Leadless-ceramic chip carrier (LCCC)





• Dual in-line package Dual in-line package (DIP)(DIP)





• Small-outline IC Small-outline IC (SOIC)(SOIC)





• Flat pack (FP)Flat pack (FP)





• Plastic-leaded chip Plastic-leaded chip carrier (PLCC)carrier (PLCC)





• Leadless-ceramic chip carrier (LCCC)Leadless-ceramic chip carrier (LCCC)




Introduction to Programmable Logic Introduction to Programmable Logic

• SPLDSPLD——Simple programmable logic Simple programmable logic devicesdevices

• CPLDCPLD——Complex programmable logic Complex programmable logic devicesdevices

• FPGAFPGA——Field-programmable gate arraysField-programmable gate arrays




Introduction to Programmable Logic Introduction to Programmable Logic

• SPLDSPLD– PAL (programmable array logic)PAL (programmable array logic)– GAL (generic array logic)GAL (generic array logic)– PLA (programmable logic array)PLA (programmable logic array)– PROM (programmable read-only memory)PROM (programmable read-only memory)




Test and Measurement Instruments Test and Measurement Instruments

• Analog OscilloscopeAnalog Oscilloscope• Digital OscilloscopeDigital Oscilloscope• Logic AnalyzerLogic Analyzer• Logic Probe, Pulser, and Current Logic Probe, Pulser, and Current

ProbeProbe• DC Power SupplyDC Power Supply• Function GeneratorFunction Generator• Digital MultimeterDigital Multimeter




Logic Gates Logic Gates

• InverterInverter• AND GateAND Gate• OR GateOR Gate• Exclusive-OR GateExclusive-OR Gate• NAND GateNAND Gate• NOR GateNOR Gate• Exclusive-NOR GateExclusive-NOR Gate




The Inverter The Inverter

Boolean expressionTruth table0 = LOW1 = HIGH

Pulsed waveforms

The output of an inverter is always the The output of an inverter is always the complement (opposite) of the input.complement (opposite) of the input.




The AND Gate The AND Gate

Boolean expression

Truth table0 = LOW1 = HIGH Pulsed waveforms

The output of an AND gate is HIGH only The output of an AND gate is HIGH only when all inputs are HIGH.when all inputs are HIGH.




The AND Gate The AND Gate

3-Input AND Gate3-Input AND Gate

4-Input AND Gate4-Input AND Gate




The OR Gate The OR Gate

Boolean expression

Truth table0 = LOW1 = HIGH

The output of an OR gate is HIGH The output of an OR gate is HIGH whenever one or more inputs are HIGHwhenever one or more inputs are HIGH

Pulsed waveforms




The OR Gate The OR Gate

3-Input OR Gate3-Input OR Gate

4-Input OR Gate4-Input OR Gate




The NAND GateThe NAND Gate

Boolean expression


The output of a NAND gate is HIGH The output of a NAND gate is HIGH whenever one or more inputs are LOW.whenever one or more inputs are LOW.

Pulsed waveforms




The NAND Gate The NAND Gate

3-Input NAND Gate3-Input NAND Gate 4-Input NAND Gate4-Input NAND Gate




The NOR Gate The NOR Gate

Boolean expression


The output of a NOR gate is LOW The output of a NOR gate is LOW whenever one or more inputs are HIGH.whenever one or more inputs are HIGH.

Pulsed waveforms




The NOR Gate The NOR Gate

3-Input NOR Gate3-Input NOR Gate 4-Input NOR Gate4-Input NOR Gate




Exclusive-OR Gate Exclusive-OR Gate

Boolean expression


The output of an XOR gate is HIGH The output of an XOR gate is HIGH whenever the two inputs are different.whenever the two inputs are different.

Pulsed waveforms




Exclusive-NOR Gate Exclusive-NOR Gate

Boolean expression


The output of an XNOR gate is HIGH The output of an XNOR gate is HIGH whenever the two inputs are identical.whenever the two inputs are identical.

Pulsed waveforms




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The Digital Logic Level