 # CHAPTER 1 Digital Concepts

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CHAPTER 1 Digital Concepts
Digital Fundamentals CHAPTER 1 Digital Concepts

Digital and Analog Quantities
Digital quantities have discrete sets of values Analog quantities have continuous values

Binary Digits, Logic Levels, and Digital Waveforms
The two binary digits are designated 0 and 1 They can also be called LOW and HIGH, where LOW = 0 and HIGH = 1

Figure 1–3 A basic audio public address system.
Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–5 Logic level ranges of voltage for a digital circuit.
Thomas L. Floyd Digital Fundamentals, 9e

Binary values are also represented by voltage levels.
Figure 1– Ideal pulses. Binary values are also represented by voltage levels. Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–7 Nonideal pulse characteristics.
Thomas L. Floyd Digital Fundamentals, 9e

Binary Digits, Logic Levels, and Digital Waveforms
tw = pulse width T = period of the waveform f = frequency of the waveform

Binary Digits, Logic Levels, and Digital Waveforms
The duty cycle of a binary waveform is defined as:

Figure 1–9 Thomas L. Floyd Digital Fundamentals, 9e

Figure 1– Example of a clock waveform synchronized with a waveform representation of a sequence of bits. Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–11 Example of a timing diagram.
Thomas L. Floyd Digital Fundamentals, 9e

Figure 1– Illustration of serial and parallel transfer of binary data. Only the data lines are shown. Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–13 Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–14 Thomas L. Floyd Digital Fundamentals, 9e

Basic Logic Operations
There are only three basic logic operations:

Basic Logic Operations
The NOT operation When the input is LOW, the output is HIGH When the input is HIGH, the output is LOW The output logic level is always opposite the input logic level.

Basic Logic Operations
The AND operation When any input is LOW, the output is LOW When both inputs are HIGH, the output is HIGH

Basic Logic Operations
The OR operation When any input is HIGH, the output is HIGH When both inputs are LOW, the output is LOW

Overview of Basic Logic Functions
Comparison function Arithmetic functions Code conversion function Encoding function Decoding function Data selection function Data storage function Counting function

Figure 1–19 The comparison function.
Compares two binary values and determines whether or not they are equal Thomas L. Floyd Digital Fundamentals, 9e

Overview of Basic Logic Functions
Arithmetic functions Perform the basic arithmetic operations on two binary values: Addition Subtraction of two values Multiplication Division

Figure 1–20 The addition function.
Thomas L. Floyd Digital Fundamentals, 9e

Code conversion function
Converts, or translates, information from one code format to another Encoding function Converts non-binary information into a binary code Decoding function Converts binary-coded information into a non-binary form

Figure 1– An encoder used to encode a calculator keystroke into a binary code for storage or for calculation.

Figure 1–22 A decoder used to convert a special binary code into a 7-segment decimal readout.
Thomas L. Floyd Digital Fundamentals, 9e

Overview of Basic Logic Functions
Data selection function Multiplexer (mux) Switches digital data from any number of input sources to a single output line Demultiplexer (demux) switches digital data from a single input to any number of output lines

Figure 1–23 Illustration of a basic multiplexing/demultiplexing application.
Thomas L. Floyd Digital Fundamentals, 9e

Overview of Basic Logic Functions
Data storage function Retains binary data for a period of time Flip-flops (bistable multvibrators) Registers Semiconductor memories Magnetic-media memories Optical-media memories

Figure 1–24 Example of the operation of a 4-bit serial shift register
Figure 1– Example of the operation of a 4-bit serial shift register. Each block represents one storage “cell” or flip-flop. Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–25 Example of the operation of a 4-bit parallel shift register.
Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–26 Illustration of basic counter operation.
Counting function Generates sequences of digital pulse that represent numbers Thomas L. Floyd Digital Fundamentals, 9e

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

Figure 1– Cutaway view of one type of fixed-function IC package showing the chip mounted inside, with connections to input and output pins. Thomas L. Floyd Digital Fundamentals, 9e

Fixed-Function Integrated Circuits
Dual in-line package (DIP)

Fixed-Function Integrated Circuits
Small-outline IC (SOIC)

Figure 1–29 Examples of SMT package configurations.
Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–30 Pin numbering for two standard types of IC packages
Figure 1– Pin numbering for two standard types of IC packages. Top views are shown. Thomas L. Floyd Digital Fundamentals, 9e

Introduction to Programmable Logic
SPLD—Simple programmable logic devices CPLD—Complex programmable logic devices FPGA—Field-programmable gate arrays

Figure 1–31 Programmable logic.
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Introduction to Programmable Logic
SPLD PAL (programmable array logic) GAL (generic array logic) PLA (programmable logic array) PROM (programmable read-only memory)

Figure 1–32 Block diagrams of simple programmable logic devices (SPLDs).
Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–34 General block diagram of a CPLD.
Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–36 Basic structure of an FPGA.
Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–38 Basic configuration for programming a PLD or FPGA.
Thomas L. Floyd Digital Fundamentals, 9e

Test and Measurement Instruments
Analog Oscilloscope Digital Oscilloscope Logic Analyzer Logic Probe, Pulser, and Current Probe DC Power Supply Function Generator Digital Multimeter

Figure 1–40 A typical dual-channel oscilloscope
Figure 1– A typical dual-channel oscilloscope. Used with permission from Tektronix, Inc. Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–41 Comparison of analog and digital oscilloscopes.
Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–42 Block diagram of an analog oscilloscope.
Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–43 Block diagram of a digital oscilloscope.
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Figure 1–44 A typical dual-channel oscilloscope
Figure 1– A typical dual-channel oscilloscope. Numbers below screen indicate the values for each division on the vertical (voltage) and horizontal (time) scales and can be varied using the vertical and horizontal controls on the scope. Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–45 Comparison of an untriggered and a triggered waveform on an oscilloscope.
Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–46 Displays of the same waveform having a dc component.
Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–47 An oscilloscope voltage probe
Figure 1– An oscilloscope voltage probe. Used with permission from Tektronix, Inc. Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–48 Probe compensation conditions.
Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–49 Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–50 Typical logic analyzer
Figure 1– Typical logic analyzer. Used with permission from Tektronix, Inc. Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–51 Simplified block diagram of a logic analyzer.
Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–52 Two logic analyzer display modes.
Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–53 A typical multichannel logic analyzer probe
Figure 1– A typical multichannel logic analyzer probe. Used with permission from Tektronix, Inc. Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–54 Typical signal generators
Figure 1– Typical signal generators. Used with permission from Tektronix, Inc. Thomas L. Floyd Digital Fundamentals, 9e

Figure 1– Illustration of how a logic pulser and a logic probe can be used to apply a pulse to a given point and check for resulting pulse activity at another part of the circuit. Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–56 Typical dc power supplies. Courtesy of B+K Precision.®
Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–57 Typical DMMs. Courtesy of B+K Precision.®
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Figure 1–60 Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–61 Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–62 Thomas L. Floyd Digital Fundamentals, 9e

Figure 1–63

Figure 1–64