Introduction to Computer

Science
Lecture 2
By
Alina Munir (Lecturer)
alina.munir@uet.edu.pk
THE HISTORY OF COMPUTING
 Events Before 1950 (1/2)
• Abacus
• Based on the technology of gears
– Blaise Pascal (1623-1662)
• Output by observing the final gear positions
– Gottfried Wilhelm Lebniz (1646-1716)
• Output by observing the final gear positions
– Charles Babbage (1792-1871)
• envisioned machines that would print results of computations
on paper
• Augusta Ada Byron (Ada Lovelace ): 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 Mark I
• Digital computer with vacuum tube
– John Atanasoff & Clifford Berry’s Atanasoff-Berry
Machine
– COLOSSOS
• Tommy Flowers
• Decoded German messages during World War II
– ENIAC (Electronic Numerical Integrator and Computer)
• John Mauchly and J. Presper Eckert
 Figure 0.3
Jacquard’s loom

(Courtesy of International
Business
Machines Corporation.
Unauthorized use not
permitted.) ⌦
 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
GenerationDates Technology Principal New Product
1 1950-1959 Vacuum tubes Commercial,
electronic computer
2 1960-1968 Transistors Cheaper computers
3 1969-1977 Integrated circuit Minicomputer
4 1978-199? LSI and VLSI Personal computers
and workstations
5 199?-20?? Microprocessor? Personal portable
computing devices
and parallel processors
6 Future
 Evolution of Processor Technology
2015

Integrated Circuit 1967

Transistor
1959 Molecular Computer 2015
Stored Program
1946
Vacuum Tube 1944 Optical Computer
2000
Electromechanical
1930
Mechanical
1896
 Processor Price Trends
$K
50
per MIPS

40
Traditional mainframes
30

20
Parallel CMOS
(Alternative mainframes
10 and mid-range)
Personal Computer
0
1990 1995 2005
BREAKTHROUGH FUTURE
TECHNOLOGIES
 Computer Science

• The scope of computer science contains

mathematics, engineering, psychology,
biology, business administration, and
linguistics.
• Research for computers：
– Hardware
– Algorithm
– Programming
Study of algorithms forms the core of computer science.

ALGORITHMS
 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/clear, executable steps that
define a termination activity.
• Example of algorithm
– Algorithms for
• Cooking (called recipes)
• Finding your way through a strange city (called directions)
• Operating washing machines
• Playing music (Music Sheet)
• Performing magic tricks

• A representation of an algorithm is called

a program.
– For humans (human readable format)
– For machines (machine compatible format)

• The process is called programming or coding.

 The study of algorithms
began as a subject in
mathematics. Indeed, the
search for algorithms was a
significant activity of
mathematicians long before
the development of today’s
computers.
 Figure 0.5
The central role of algorithms
in computer science
THE SCIENCE OF ABSTRACTION
 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
f=a+b
b