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Introduction to Computing

Introduction to Computing. CMSC 120: Visualizing Information 1/29/08. What is Computing?. To determine by calculating To use a computer. What is a Computer?. A device that accepts information (data), processes it according to specific instructions,

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Introduction to Computing

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  1. Introduction to Computing CMSC 120: Visualizing Information 1/29/08

  2. What is Computing? • To determine by calculating • To use a computer What is a Computer? • A device that accepts information (data), • processes it according to specific instructions, • and provides the results as new information

  3. *A computer: a person who works with numbers First Computers Pen and Paper People 0 1 2 3 4 5 6 7 8 9 Number Systems Abacus

  4. Mechanical Age (1450-1840) Slide Rule • Early 1600s • An analog computer • Blaise Pascal (1642) • A gear driven adding machine Pascaline Analog: represents data by measurement of a continuous physical variable

  5. Mechanical Age (1450-1840) Stepped Reckoner • Gottfried Wilhelm von Leibniz (1670s) • Add, subtract, multiply, divide • Mechanically unreliable

  6. Mechanical Age (1450-1840) Punch Card • Joseph Jacquard (1810) • Weaving instructions for looms stored in cards with holes punched in them

  7. Mechanical Age (1450-1840) The Analytical Engine • Followed program in punched cards • Store information in memory unit • Make decisions The Difference Engine (1822) • Charles Babbage

  8. Analytical Engine Anecdote • Babbage’s collaborator was Ada, Countess of Lovelace, daughter of Lord Bryon • Sponsored, tested, publicized device • “First Programmer” • Stated that the engine would never “originate anything” • A machine, no matter how powerful, could think

  9. Electro-mechanical Age (1840 – 1940) • Hermann Hollerith (end 19th century) • Created to tabulate US Census • Used electricity • Information punched into cards • Metal pins open and closed electrical circuits Electronic Tabulating Machine • Population: 63 million; 6 weeks • Founding product of International Business Machines (IBM)

  10. Electro-mechanical Age (1840 – 1940) • IBM + Harvard under leadership of Howard Aiken (1930s) • Storage: Mechanical relay telephone switches • Input: Punch Cards • Output • No decision making 51 feet in length 5 tons 750, 000 parts Mark I What is the difference between a calculator and a computer?

  11. The First Computer Bug • Grace Hopper (1909 – 1992) • One of first programmers of Mark I • Developed first compiler

  12. Electronic Age (1840 – Today) Electronic Numerical Integration and Calculator (ENIAC) • John Mauchly and J. Presper Eckert (finished 1946) • Initially secret military project begun during WWII • University of Pennsylvania

  13. Electronic Age (1840 – Today) • Occupied 1500 square feet • Weighed 30 tons • Used vacuum tubes • >17,000 • Able to make decisions: first true computer • Programming involved wiring and switch flipping ENIAC

  14. Electronic Age (1840 – Today) • John von Neumann (1940s) • Storing computer instructions in a central processing unit (CPU) • No longer necessary to flip switches or rewire • Large Corporations, US Government Stored Program Computer • Processing Model: • Input data • Store data while being processed • Process data according to specific instructions • Output the results in the form of new data

  15. Electronic Innovations • Vacuum tubes • Large and expensive • UNIVAC: 35 tons • 1000 calculations per second • 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

  16. Electronic Innovations • 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

  17. Modern Computers • 1951 – 1958: Vacuum tubes (First Generation) • 1959 – 1964: Transistors (Second Gen) • 1965 – 1970: Integrated Circuits (Third Gen) • 1970 + : Large Scale Chips and Microprocessors (Fourth Gen)

  18. Modern Computers • Microprocessor: a CPU an a single chip • Designed in 1970 by Marcian Hoff (Intel Corporation) • Microcomputer: a desktop size computer • ALTAIR (1975) • Apple (Stephen Wozniak and Steven Jobs; 1977)

  19. The State of Modern Computing • Computing power doubles every 18-24 months From the BBC

  20. Hardware (Computer Architecture) • Input Devices • Memory • Central Processing Unit • Output Devices Input Memory Output CPU

  21. Memory • Read Only Memory (ROM) • Most basic operating instructions • Permanent • Random Access Memory (RAM) • Main memory • Data and instructions are temporarily stored • Registers • Temporary memory locations within the CPU • Auxiliary Memory

  22. CPU • Directs all activities of the computer • All information flows through the CPU • “Brain” • Only executes tasks according to instructions it has been given • Arithmetic Logic Unit (ALU) • Adds • Compares

  23. Software • Computer programs • Interface between computer and user • Disk Operating System (DOS) • MS-DOS, Windows, Linux, UNIX • Graphical User Interface (GUI)

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