Computer Science — An Overview J. Glenn Brookshear

Chapter Zero

Introduction

Outline

• The Study of Algorithms

• The Origins of Computer Machines

• The Evolution of Computer Science

• Abstraction

• Ethical/Social/Legal Repercussions

• Social Issues

• Additional Reading

What is Computer ？

• Kinds of Computers– MACs

• Steven Jobs & Steplen Wozniak constructed APPLE Computer in 1976

– PCs• 1981 IBM has its first PC

– Workstations

– Supercomputers

– Embedded Computer

• Macintosh: personal computer with– one main manufacturer: Apple– one operating system: MACOS

• Advantages:– simplicity and uniformity– good for beginners and casual users– desk top publishing, graphic design

• Disadvantages:– lack of variety of software– closed system design

Apple - Macs

Personal Computer (PC)

•IBM Compatible PC (or PC)– many manufacturers, but one design– one operating system: Windows (98/NT)

•Advantages:– reasonable simplicity (after Windows 95)– huge variety of software– open system design, very adaptable

•Disadvantages:– hardware variations cause incompatibilities– unexpected complexities arise

Killer Applications

• Killer Application of Internet: e-mail

• Killer Application of PC: Lotus 1-2-3

Workstations

•Workstation: shared lab computer– many manufacturers (Sun, HP...)– one operating system (family): Unix

•Advantages:– highly adaptable and customizable– free academic software (?)– good for programmers, groups, systems

•Disadvantages:– can be difficult for beginners– variations in versions of Unix

Supercomputers

•A supercomputer runs heavy duty programs:– weather forecasting, cosmology, particle

physics, vehicle design, flow simulation

•Vector supercomputers do the same operation to lots of numbers at the same time. Effective, but not general purpose.•Parallel supercomputers have many processors and memory banks, and an interconnect. Transputer has been used in some of these!

Embedded Computers

• Modern processor, yet simple enough to describe. Complete system on one chip:

– processor, memory, I/O, process manager

• Has no keyboard/screen etc. of its own because particularly suitable for:

– embedding in consumer products (ex: hand-held devices, IA)

– building parallel computers

Thinking

• Are computers smart?– Yes! Why?– No! Why?

• What is the intelligence of the computers?– By executing a list of commands, your

computer performs the task.– Computers never think.

Topics

• The Study of Algorithms

• The Origins of Computer Machines

• The Evolution of Computer Science

• Abstraction

• Ethical/Social/Legal Repercussions

• Social Issues

• Additional Reading

Algorithm

• An algorithm is a set of steps that defines how a task is performs.– Computer program is just the form that is

compatible with machine.

• Formal definition of algorithm:– An algorithm is an ordered set of unambiguous,

executable steps that define a termination activity.

• Example of algorithm

Figure 0.1 (1/2)An algorithm for a magic trick

Figure 0.1 (2/2)An algorithm for a magic trick

Figure 0.2The Euclidean algorithm for finding the greatest

common divisor of two positive integers

M=12 N=8

M=12 N=8 R=4

M=8 N=4

M=8 N=4 R=0

R≠0 R=0 GCD=N=4

Performance of a Task

• Human thinks the algorithm.– Once an algorithm has been found, the

understanding of the principles and theorem are no longer requires.

• The task is reduced to the process of following directions in the algorithm.

• The level of intelligence displayed by machines is limited as that of algorithms.

Computers

• Software = algorithm programs– How algorithms are discovered (Chapter 4)– Programming language (Chapter 5)– Software engineering (Chapter 6) – Data storage (Chapters 7,8,9)

• Hardware– Design and construction of machines (Chapters 1, 2)

• Operating System and Network (Chapter 3)

Topics

• The Study of Algorithms

• The Origins of Computer Machines

• The Evolution of Computer Science

• Abstraction

• Ethical/Social/Legal Repercussions

• Social Issues

• Additional Reading

Events Before 1950 (1/2)

• Abacus

• Based on the technology of gears– Blaise Pascal (1623-1662)– Bottfriedn Wilhelm Lebniz (1646-1716)– Charles Babbage (1792-1871)

• Augustra Ada Byron: First Programmer in the world

– Joseph Jacquard’s loom (1801) – Herman Hollerith (1860-1929)

Events Before 1950 (2/2)

• Electronic mechanical machine– Georage Stibitz (1940)– Howard Aiken & IBM’s Maker I

• Digital computer with vacuum tube– John Atanasoff & Clifford Berry’s Atanasoff-

Berry Machine– COLOSSOS– ENIAC

(Courtesy of International Business

Machines Corporation. Unauthorized use not

permitted.)

Figure 0.3Jacquard’s loom

Figure 0.4

The Mark I Computer

The Mark I Computer, completed in 1940 at Harvard University

Valves (ENIAC, UNIVAC...)

“ Where... the ENIAC is equipped with 18,000 vacuum tubes and weighs 30 tons, computers in the future may have 1,000 vacuum tubes and perhaps weigh just 1-1/2 tons.” Popular Mechanics, March 1949, p.258

Events 1952-1959

•1952 ： drum memory (IBM702) core memory (whirlwind)•1956 ： Keyboard input (whirlwind)•1957 ： DEC founded Photograph scanned, processed, redisplayed by Computer•1959 ： transistors (IBM1401) PDP-1 (4k 18bit words, paper tape, CRT, $159,000) Integrated circuit

Transistors

Integrated Circuits

Events 1960-1968•1961 ： IBM7090•1962 ： Burroughs 6500,CTSS time-sharing system•1963 ： SKETCHPAD (precursor to CAD)•1964 ： PDP-8 (first mass-produced minicomputer), IBM 360, Chip in a Dip CDC6600•1965 ： Stereo headset (first VR helmet)•1967 ： CMOS integrated circuits•1968 ： Mouse•“I got the idea for the mouse while attending a talk at a computer conference. The speaker was so boring that I started daydreaming and hit upon the idea.”

• Doug Engelbert

Events 1969-1977

•1971 ： Intel 4004 (first microprocessor), Poketronic (first pocket calculator)•1972 ： Intel 8008, HP-35 calculator ($395)•1973 ： Ethernet•1974 ： Intel 8080•1975 ： DEC system 10, Z80, 6502, 6800, IBM RISC project •1976 ： Cray-1 supercomputer, Last slide rule, Adventure game•1977 ： Apple II (6502, 16K RAM, 16K ROM, $1298), Commodore PET (6502, 4K RAM, 14K ROM, $595)

Microprocessors

•The first microprocessor: Intel 4004 calculator chip, available 1971.

– designed by Ted Hoff– 2300 transistors, 4-bit device, 60,000

instructions/sec for $300.

•Intel 8008 sponsored by a company planning a terminal - too slow. Introduced as a microprocessor 1972.

•Intel 8080 launched 1974 .

Events 1978-1990•1978 ： Intel 8086, 8088 •1979 ： Ethernet adopted by Xerox, DEC, Intel•1980 ： 64K DRAM, Motorola 68000, Intel 80186, NS16000•1981 ： IBM PC, Xerox ALTO, Osborne I portable•1982 ： SONY announces CD technology•1987 ： 4Mbit DRAM•1989 ： Intel i486

Motorola 68K

•Motorola 6800 designed by Chuck Peddle; moved to MOS technology and designed 6502.

•These microprocessors initiated the PC revolution.

•Motorola 68000 launched 1979; delivered the capabilities of minicomputers at a fraction of the cost.

•Immediately used as the technology base of new companies (SUN and Apple).

Computing Trends

•1990s: cost of computing and network access drops to consumer price points

– emergence of consumer appliances, networks, servers

•1995+: continuing increase in performance/cost, higher integration, rapid advances in interfaces (eg LCDs)

– emergence of portable and wearable computers, pervasive networking, massive media databases

The Origins of Computing Machines

Generation Dates Technology Principal New Product1 1950-1959 Vacuum tubes Commercial,

electronic computer2 1960-1968 Transistors Cheaper computers3 1969-1977 Integrated circuit Minicomputer4 1978-199? LSI and VLSI Personal computers

and workstations5 199?-20?? Microprocessor? Personal portable

computing devices and parallel processors

Evolution of Processor Technology

2015

2000

1959

1967

2015

19461944

1930

1896

Electromechanical

Mechanical

Vacuum Tube

Stored Program

Transistor

Integrated Circuit

Optical Computer

Molecular Computer

How Fast to Market?

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80

Penetration of households %

Videocassette Recorder

1975-1988

Personal Computer 1975-

1995

Cable 1950-1991

Telephone 1876-1950

Years after coming to market

Overall Technology Characteristics1992 1995 1998 2001 2004 2007

Feature Size (um) 0.50 0.35 0.25 0.18 0.12 0.10

Gates/Chip 300K 800K 2M 5M 10M 20M

Bits/Chip

DRAM 16M 64M 256M 1G 4G 16G

SRAM 4M 16M 64M 256M 1G 4G

Wafer Processing

Cost ($/sq cm) 4.00 3.90 3.80 3.70 3.6 3.50

Performance (MHz)

Off Chip 60 100 175 250 350 500

On Chip 120 200 350 500 700 1,000

Processor Price Trends

20

40

50

30

10

0200519951990

$K per MIPS

Traditional mainframes

and mid-range)(Alternative mainframes

Parallel CMOS

Personal Computer

Comparison since 1950Year Name Size

(cu ft) Power (watts)

Performance (adds/ sec)

Memory (KB)

1951 UNIVAC I 1000 124,500 1,900 48 1964 IBM S360/ 50 60 10,000 500,000 64 1965 PDP-8 8 500 330,000 4 1976 Cray-1 58 60,000 166,000,000 32,768 1981 IBM PC 1 150 240,000 356 1991 HP 9000/ 750 2 500 50,000,000 16,384

Year Price Performance / Price vs

UNIVAC

Adjusted Price

(1991 $)

Performance / Price vs

UNIVAC 1951 $1,000,000 1 $4,533,607 1 1964 $1,000,000 263 $3,756,502 318 1965 $16,000 10,855 $59,947 13,135 1976 $4,000,000 21,842 $7,675,591 51,604 1981 $3,000 42,105 $3,702 154,673 1991 $7,400 3,556,188 $7,400 16,122,356

Semiconductors - Basic Parameters

Transmission Costs & Capacity

Storage Price Trends

0.1

10

100

1

0.01

0.001

2005200019951990

Seminconductor (DRAM)

Magnetic Technology

Optical

Technology Trends

•Sustained advance in:– processing– communication– storage

•Significant improvements– integration - move towards single-chip

systems– communication - optical and wireless– storage density - CDROM, DVD etc

Market Trend - “Consumer Friendly”

•Visual Communication– 3D sounds and images

•Internet Explosion– Information and communication

•Information Appliances– Personal organizers– Mobile phones– Wearable computers

Topics

• The Study of Algorithms

• The Origins of Computer Machines

• The Evolution of Computer Science

• Abstraction

• Ethical/Social/Legal Repercussions

• Social Issues

• Additional Reading

Computer Science

• The scope of computer science contains mathematics, engineering, psychology, biology, business administration, and linguistics.

• Research for computers ：– Hardware– Algorithm– Programming

Algorithm

• All of questions in the computer science are based on the study of algorithms.

• Algorithm is the central point of the computer science.

Figure 0.5The central role of algorithms

in computer science

Topics

• The Study of Algorithms

• The Origins of Computer Machines

• The Evolution of Computer Science

• Abstraction

• Ethical/Social/Legal Repercussions

• Social Issues

• Additional Reading

Envision Computer Systems

• Today’s computer systems are extremely complex and can be overwhelming when viewed in all their detail.

• We envision the computer in terms of component– ignore the internal details of components– concentrate on how components interact with

other components

Abstraction

• Abstraction is a simplification technique.– extract the external properties for components– ignore the internal details

• Use abstract modules to construct more complex function

a

bf = a + b

Topics

• The Study of Algorithms

• The Origins of Computer Machines

• The Evolution of Computer Science

• Abstraction

• Ethical/Social/Legal Repercussions

• Social Issues

• Additional Reading

Ethical/Social/Legal Repercussions

• Engineers should take more care about their environment and society.

• There is often no single correct answer, and many valid solutions are compromises between opposing views.

• We need to listen, recognize, debate and expand our’s own opinion as new insights are gained.

Topics

• The Study of Algorithms

• The Origins of Computer Machines

• The Evolution of Computer Science

• Abstraction

• Ethical/Social/Legal Repercussions

• Social Issues

• Additional Reading

Social Issues (1/2)

• These questions help you understand some of the ethical/social/legal issues associated with the field of computing.

1. Is our society better after the computer revolution?

2. Is it acceptable to participate in today’s technical society without understanding the technology?

Social Issues (2/2)

5. Should a government regulate computer and its applications?

7. As technology advances, our educational system is challenged to reconsider at which topics are presented.

Example: spelling skill/reading/long division/trigonometric function?

Topics

• The Study of Algorithms

• The Origins of Computer Machines

• The Evolution of Computer Science

• Abstraction

• Ethical/Social/Legal Repercussions

• Social Issues

• Additional Reading

Additional Reading

• Dejoie, D., G. Fowler, and D. Paradice. Ethical Issues in Information Systems. Boston: Boyd and Fraser, 1991.

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