1. EI205 Lecture 1
Dianguang Ma
Fall, 2008

2. Textbook
Digital Fundamentals 7/E by Thomas L Floyd, China Science Press & Pearson Education, , REQUIRED TEXT.

3. Digital Fundamentals 7/E

4. Topics to be Covered
Chapters 1 — 6
Sections 7-1 — 7-4
Chapters 8 — 10
Sections 12-1 — 12-6
Sections 13-1 — 13-3

5. Grading Policy
Problem Sets: ?%
Midterm Exam: ?%
Final Exam: ?%

6. 1 INTRODUCTORY DIGITAL CONCEPTS

7. 1-1 DIGITAL AND ANALOG QUANTITIES

8. Introductory Paragraph
Electronic circuits can be divided into two broad categories, digital and analog. Digital electronics involves quantities with discrete values, and analog electronics involves quantities with continuous values. Although you will studying digital fundamentals in this book, you should also know about analog because many applications require both.

9. What’s Analog Quantity?
An analog quantity, having continuous values, takes on all the infinite values in between, say, [a, b].

10. What’ s Digital Quantity?
A digital quantity has a set of discrete values.

11. Analog Example
A public address system, used to amplify sound so that it can be heard by large audience, is one example of an application of analog electronics.

12. Digital Example
A computer system is one example of an application of digital electronics.

13. A Mixed System
The compact disk (CD) player is an example of a system in which both digital and analog circuits are used.

14. The Digital Advantage
Digital has certain advantages over analog, e.g., digital data can be stored, processed, and transmitted more efficiently and reliably than analog data.

15. 1-2 BINARY DIGITS, LOGIC LEVELS, and DIGITAL WAVEFORMS

16. Introductory Paragraph
Digital electronics involves circuits and systems in which there are only two possible states. These states are represented by two different voltage levels: a HIGH and a LOW. The two states can also be represented by current levels, open and closed switches, or lamps turned on and off. In digital systems, combinations of the two states, called codes, are used to represent numbers, symbols, alphabetic characters, and other types of information. The two-state number system is called binary, and its two digits are 0 and 1. A binary digit is called a bit.

17. Binary Digits
The two digits in the binary system, 1 and 0, are called bits, which is a contraction of the words binary digit.

18. How to represent 0 and 1?
In digital circuits, two different voltage levels are used to represent the two bits. The higher/lower voltage level is referred to as a HIGH/LOW, or H/L.

19. Logic Levels
The voltages used to represent a 1 and a 0 are called logic levels.
In a practical digital circuit, a HIGH can be any voltage between a specified minimum value and a specified maximum value. Likewise, a LOW can be any voltage between a specified minimum and a specified maximum.

20. Positive Logic System
A 1 is represented by HIGH and a 0 is represented by LOW.

21. Negative Logic System
A 0 is represented by HIGH and a 1 is represented by LOW.

22. Codes
Groups of bits (combination of 1s and 0s), called codes, are used to represent numbers, letters, symbols, instructions, and anything else required in a given application.
The American Standard Code for Information Interchange (ASCII) – pronounced “askee” – is a universally accepted alphanumeric code used in most computers and other electronic equipment. 1

23. ASCII

24. Digital Waveforms
Digital waveform consists of a series of pulses, (voltage levels that are changing back and forth between the HIGH and LOW levels).

25. Pulse Train
Digital waveforms are sometimes called pulse trains.

26. Ideal Pulses
A single positive-going pulse is generated when the voltage goes from its normally LOW level to its HIGH level and then back to its LOW level.
A single negative-going pulse is generated when the voltage goes from its normally HIGH level to its LOW level and then back to its HIGH level.

27. Nonideal Pulse
The time required for the pulse to go from its LOW (HIGH) level to its HIGH (LOW) level is called the rise (fall) time. In practice, it is common to measure rise (fall) time from 10%(90%) of the pulse amplitude to 90%(10%) of the pulse amplitude.

28. Nonideal Pulse
The pulse width is a measure of the duration of the pulse and is often defined as the time interval between the 50% points on the rising and falling edges.

29. Nonideal Pulse
The pulse width is a measure of the duration of the pulse and is often defined as the time interval between the 50% points on the rising and falling edges.

30. Period Pulse
A periodic waveform is one that repeats itself at a fixed interval, called a period (T ). The frequency (f ) is the rate at which it repeats itself and is measured in hertz (Hz). The relationship between f and T is expressed as follows:

31. Period Pulse
The duty cycle (D ) is defined as the ratio of the pulse width (tw ) to the period (T ) and can be expressed as a percentage.

32. Nonperiodic Pulse
A nonperiodic waveform, of course, does not repeat itself at fixed intervals and may be composed of pulses of randomly differing pulses widths and/or randomly differing time intervals between the pulses.

33. A Digital Waveform Carries Binary Information
Binary information that is handled by digital systems appears as waveforms that represent sequences of bits. When the waveform is HIGH, a binary 1 is present; when the waveform is LOW, a binary 0 is present. Each bits in a sequence occupies a defined time interval called a bit time, or bit interval.

34. The Clock
In digital systems, all digital waveforms are synchronized with a basic timing waveform, called the clock. The clock is a periodic waveform. The clock waveform itself does not carry information.

35. The Clock
In digital systems, all digital waveforms are synchronized with a basic timing waveform, called the clock.

36. More about Clocks
Clocks are used extensively in computers. All processors run with an internal clock. Modern chips run at frequencies up to 3 GHz. This works out to a period as little as 0.33 ns.

37. Timing Diagrams
A timing diagram is a graph of digital waveforms showing the actual time relationship of two or more waveforms and how each changes in relation to the others.

38. Data Transfer
Data refers to groups of bits that convey some type of information. Binary data, which are represented by digital waveforms, must be transferred from one circuit to another within a digital system or from one system to another in order to accomplish a given purpose.

39. Serial Data Transfer
When bits are transferred in serial form from one point to another, they are sent one bit at a time along a single conductor. To transfer n bits in series, it takes n time intervals.

40. Parallel Data Transfer
When bits are transferred in parallel form, all the bits in a group are sent out on separate lines at the same time. There is one line for each bit. To transfer n bits in parallel, it takes one time interval.

41. 1-3 BASIC LOGIC OPERATIONS

42. Introductory Paragraph
In its basic form, logic is the realm of human reasoning that tells you a certain proposition (declarative statement) is true if certain conditions are true. Propositions can be classified as true or false. Many situations and processes that you encounter in your daily life can be expressed in the form of propositional, or logic, functions. Since such functions are true/false or yes/no statements, digital circuits with their two-state characteristics are applicable.

43. Logic Functions
Several propositions, when combined, form propositional, or logic functions. For example, the propositional statement “The light is on” will be true if the “The bulb is not burned out” is true and if “The switch is on” is true. The first statement is then the basic proposition, and the other two statements are the conditions on which the proposition depends.

44. Boolean Algebra
In 1850s, the Irish logician and mathematician George Bool developed a mathematical system for formulating logic statements with symbols so that problems can be written and solved in a manner similar to ordinary algebra.

45. Basic Logic Operations
In Boolean algebra, there are three basic logic operations: NOT, AND, and OR.
Each of the three basic logic operations produces a unique response (output) to a given set of conditions (inputs).
The standard distinctive shape symbols for the three basic logic operations are shown below.

46. Logic Gates
A circuit that performs a specified basic logic operation is called a logic gate. Logic gates form the building blocks for digital systems.
The true/false statements mentioned earlier are represented by a HIGH (true) and a LOW (false).
AND and OR gates can have any number of inputs.

47. The NOT Operation
The NOT operation changes one logic level to the opposite logic level.
The NOT operation is implemented by a logic circuit known as an inverter (NOT gate).

48. The AND Operation
The AND operation produces a HIGH output only if all the inputs are HIGH. When any or all inputs are LOW, the output is LOW.
The AND operation is implemented by a logic circuit known as an AND gate.

49. The OR Operation
The OR operation produces a LOW output only if all the inputs are LOW. When any or all inputs are HIGH, the output is HIGH.
The OR operation is implemented by a logic circuit known as an OR gate.

50. 1-4 BASIC LOGIC FUNCTIONS

51. Introductory Paragraph
The three basic logic elements AND, OR, and NOT can be combined to form more complex logic circuits that perform many useful operations and that are used to build complete digital systems. Some of the common logic functions are comparison, arithmetic, code conversion, encoding, decoding, data selection (multiplexing, demultiplexing), storage, and counting. This section provides a general overview of these important functions so that you can begin to see how they form the building blocks of digital systems such as computers.

52. The Comparison Function
Magnitude comparison is performed by a logic circuit called a comparator. A comparator compares two quantities and indicates if they are equal or not equal and, if not equal, which is greater.

53. The Longest Man

54. The Tallest Buildings

55. The Arithmetic Functions
Addition/subtraction/multiplication/division is performed by a logic circuit called an adder/subtracter/multiplier/divider. An adder adds two binary numbers and generates a sum and a carry.
A Subtracter/multiplier/divider can be implemented by using an adder in conjunction with other circuits.

56. The Encoding Function
The encoding function is performed by a logic circuit called an encoder. The encoder converts (noncoded) information (for example, a calculator keystroke) into some binary code.

57. The Decoding Function
The decoding function is performed by a logic circuit called an decoder. The decoder converts a binary code into some (noncoded) information (for example, a decimal digit).

58. The Multiplexing Function
The multiplexing function is performed by a logic circuit called a multiplexer, or mux for short. The mux switches digital data from several input lines onto a single output line in a specified time sequence.

59. The Demultiplexing Function
The demultiplexing function is performed by a logic circuit called a demultiplexer, or demux for short. The demux switches digital data from one input line to several output lines in a specified time sequence.

60. Time Division Multiplexing (TDM)
Multiplexing and demultiplexing are used when data from several sources are to be transmitted over one line to a distant location and redistributed to several destinations.

61. A KVM Switch
This KVM switch allows four computers to share a single keyboard, video monitor, and mouse.

62. The Storage Function
When an input is applied to a circuit, the output will change its state, but it will remain in the new state even after the input is removed. This property of retaining its response to a momentary input is called memory.
The purpose of storage is to retain binary data for a period of time. Common types of storage devices are flip-flops, registers, semiconductor memories, magnetic disks, magnetic tape, and optical disks.

63. Flip-flops
The flip-flop is a bistable (two stable states) logic circuit that can store only one bit at a time, either a 1 or a 0. The output of a flip-flop indicates which bit it is storing.

64. Flip-flops

65. Registers
A register is formed by combining several flip-flops so that groups of bits can be stored.
In addition to storing bits, registers can be used to shift the bits from one position to another within the register or out of the register to another circuit; therefore, these devices are known as shift registers.

66. Semiconductor Memories
Semiconductor memories are typically used for storing large numbers of bits.

67. Magnetic memories are used for mass storage of binary data.

68. The Motherboard

69. Attractive Woman with Tape Reel and Tape Drive

70. The Counting Function
The counting function is performed by a logic circuit called a counter. The basic purpose of counters is to count events or to generate a particular code sequence.

71. 1-5 DIGITAL INTEGRATED CIRCUITS

72. Introductory Paragraph
All the logic elements and functions that have been discussed – and many more – are available in integrated circuit (IC) form. Modern digital systems use ICs almost exclusively in their designs because of their small size, high reliability, low cost, and low power consumption. It is important to be able to recognize the IC packages and to know how the pin connections are numbered, as well as to be familiar with the way in which circuit complexities and circuit technologies determine the various IC classifications.

73. IC
A monolithic IC is an electronic circuit that is fabricated on a single chip of semiconductor material (usually silicon) called substrate. All the components that make up the circuit – transistors, diodes, resistors, and capacitors – are an integral part of that single chip.

74. IC Packages
ICs are enclosed in a protective casing or encapsulation which is made of plastic (for normal temperature range and commercial, low cost applications) or ceramic (for high temperature range and industrial and military applications).

75. Through-hole Mounted or Surface Mounted
IC packages are classified according to the way they are mounted on printed circuit (PC) boards as either through-hole mounted or surface mounted.

76. DIP
The through-hole packages have pins (leads) that are inserted through holes in the PC board and can be soldered to conductors on the opposite side. The most common type of through-hole package is the dual-in-line package (DIP).

77. SMT
The pins of the surface-mount technology (SMT) packages are soldered directly to the conductors on one side of the board, leaving the other side free for additional circuits.

78. Common Types of SMT Packages
Four common types of SMT packages are the SOIC (small-outline IC), the PLCC (plastic leaded chip carrier), the LCCC (leadless ceramic chip carrier), and the flat pack (FP).

79. Pin Numbering
All IC packages have a standard format for numbering the pins. Looking at the top of the package, pin 1 is indicated by an identifier that can be either a small dot, a notch, or a beveled edge. Starting with pin 1, the pin numbers increase as you go counterclockwise.

80. Integrated Circuit Complexity Classification
ICs are classified according to their complexity depending on the number of equivalent gate circuits on a single chip:
Small-scale integration (SSI): < 12, gates, flip-flops.
Medium-scale integration (MSI): 12 – 99, encoders, decoders, registers, multiplexers (data selectors), adders.
Large-scale integration (LSI): 100 – 9,999, memories.
Very large-scale integration (VLSI): 10,000 – 99,999, microprocessors, single-chip computers.
Ultra large-scale integration (ULSI): 100,000 – 999,999
Giga-scale integration (GSI): > 1000,000

81. Integrated Circuit Technologies
The types of transistors with which all ICs are implemented are either BJTs (bipolar junction transistors) or MOSFETs (metal-oxide semiconductor field-effect transistors).
Two types of digital circuit technology that use BJTs are TTL (transistor-transistor logic) and ECL (emitter-coupled logic).
The major circuit technologies that use MOSFETs are CMOS (complementary MOS) and NMOS (n-channel MOS).
SSI and MSI circuits are generally available in both TTL and CMOS.
LSI, VLSI, ULSI, and GSI are generally implemented with CMOS or NMOS because it requires less area on a chip and consumes less power.

82. Homework 1
Problems 2, 6, 11, 12, 16, 20.