Transcript Introduction to Computing - Bryn Mawr Computer Science

Introduction to
Computing
CMSC 120: Visualizing Information
1/29/08
What is Computing?
To determine by calculating
 To use a computer
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What is a Computer?
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A device that accepts information (data),
processes it according to specific instructions,
and provides the results as new information
*A computer: a person who works with numbers
First Computers
Pen and Paper
People
01234
56789
Number Systems
Abacus
Mechanical Age (1450-1840)
Slide Rule
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Early 1600s
An analog computer
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Blaise Pascal (1642) Pascaline
A gear driven adding machine
Analog: represents data by measurement of
a continuous physical variable
Mechanical Age (1450-1840)
Stepped Reckoner
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Gottfried Wilhelm
von Leibniz (1670s)
Add, subtract,
multiply, divide
Mechanically
unreliable
Mechanical Age (1450-1840)
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Punch Card
Joseph Jacquard (1810)
Weaving instructions for looms stored in cards with
holes punched in them
Mechanical Age (1450-1840)
The Difference Engine (1822)
 Charles Babbage
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The Analytical Engine
Followed program in punched cards
Store information in memory unit
Make decisions
Analytical Engine Anecdote
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Babbage’s collaborator was Ada, Countess of
Lovelace, daughter of Lord Bryon
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Sponsored, tested, publicized device
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“First Programmer”
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Stated that the engine would never “originate
anything”
– A machine, no matter how powerful, could think
Electro-mechanical Age (1840 – 1940)
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Electronic Tabulating Machine
Population: 63 million; 6 weeks
Founding product of International
Business Machines (IBM)
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Hermann Hollerith (end
19th century)
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Created to tabulate US
Census
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Used electricity
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Information punched into
cards
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Metal pins open and
closed electrical circuits
Electro-mechanical Age (1840 – 1940)
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IBM + Harvard under
leadership of Howard
Aiken (1930s)
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Storage: Mechanical
relay telephone
switches
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Input: Punch Cards
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Output
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No decision making
51 feet in length
5 tons
750, 000 parts
Mark I
What is the difference
between a calculator and
a computer?
The First Computer Bug
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Grace Hopper (1909 –
1992)
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One of first programmers
of Mark I
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Developed first compiler
Electronic Age (1840 – Today)
Electronic Numerical Integration and Calculator (ENIAC)
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John Mauchly and J. Presper Eckert (finished 1946)
Initially secret military project begun during WWII
University of Pennsylvania
Electronic Age (1840 – Today)
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Occupied 1500 square
feet
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Weighed 30 tons
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Used vacuum tubes
– >17,000
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Able to make decisions:
first true computer
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Programming involved
wiring and switch flipping
ENIAC
Electronic Age (1840 – Today)
Stored Program Computer
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Processing Model:
–
–
–
–
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John von Neumann
(1940s)
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Storing computer
instructions in a central
processing unit (CPU)
– No longer necessary to flip
switches or rewire
 Large Corporations,
Input data
Store data while being processed Government
Process data according to specific instructions
Output the results in the form of new data
US
Electronic Innovations
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Vacuum tubes
– Large and expensive
– UNIVAC: 35 tons
– 1000 calculations per second
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Transistor: semiconductor used as an amplifier or
electronically controlled switch
–
–
–
–
Reduced size
10,000 claculations per second
IBM model 650 (1960s)
Magnetic tape replaced punched cards
Electronic Innovations
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Integrated Circuits
– Replacement of transistors with integrated circuits or chips
– Silicon blocks with logic circuits etched onto surface
– Millions of calculations per second
– IBM System 360 was one of the first computers to use
integrative circuits
– Hospitals and Universities could now own computers
Modern Computers
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1951 – 1958: Vacuum tubes (First Generation)
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1959 – 1964: Transistors (Second Gen)
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1965 – 1970: Integrated Circuits (Third Gen)
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1970 + : Large Scale Chips and Microprocessors
(Fourth Gen)
Modern Computers
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Microprocessor: a CPU an a single chip
– Designed in 1970 by Marcian Hoff (Intel Corporation)
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Microcomputer: a desktop size computer
– ALTAIR (1975)
– Apple (Stephen Wozniak and Steven Jobs; 1977)
The State of Modern Computing
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From the BBC
Computing power
doubles every 18-24
months
Hardware
(Computer Architecture)
Input Devices
 Memory
 Central Processing Unit
 Output Devices
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Input
Memory
CPU
Output
Memory
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Read Only Memory (ROM)
– Most basic operating instructions
– Permanent
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Random Access Memory (RAM)
– Main memory
– Data and instructions are temporarily stored
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Registers
– Temporary memory locations within the CPU
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Auxiliary Memory
CPU
Directs all activities of the computer
 All information flows through the CPU
 “Brain”
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– Only executes tasks according to instructions
it has been given
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Arithmetic Logic Unit (ALU)
– Adds
– Compares
Software
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Computer programs
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Interface between computer and user
– Disk Operating System (DOS)
– MS-DOS, Windows, Linux, UNIX
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Graphical User Interface (GUI)