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History of Computers
Topic 1

A Brief History

 

  1. Early societies

    1. People notice patterns

    2. Natural patterns and counting

    3. People devised counting mechanism

      1. Keep track and predict seasons

      2. Use the sun, moon, stars, etc.

      3. Became intertwine with magic

      4. Source of power and supernatural ability

  2. Mechanisms

    1. Sticks

    2. Marks on a wall

    3. People kept records

      1. Help in predictions

      2. Teach the next generation

  3. Monumental structures

    1. Calendars

    2. Stonehenge was built in England around 2800 BC

      1. Oriented towards equinoxes and solstices

        1. Equinox - the date when day and night are equal

        2. March 20/21 and September 22/23 each year

        3. Solstice - either the longest or shortest day of the year

        4. Longest day June 20/21

        5. Shortest day December 20/21

      2. Used for agriculture

  4. Civilization

    1. Government tax records

    2. Ben Franklin - two things are certain in life - death and taxes!

    3. Abacus - earliest known counting/calculation instrument

      1. Used to aid mental calculations 3,000 BC

      2. The abacus is invented in Babylonia

      3. Used by Greeks and Romans

  5. Mathematicians built mechanical counting machines during the Renaissance

    1. Expansion of business

      1. Predict seasons

      2. insurance companies - actuarial tables

    2. Military

      1. Artillery and guns

      2. After 19th century, code breaking, secret communications, etc.

    3. Definition of a computer

      1. Original - people whose job involved calculating or computing

      2. Now - an electrical device that computes

  6. 20th Century

    1. Computers are used in everything

    2. Military - code breaking, secret communications, etc.

    3. Electronic Numerical Integrator And Computer (ENIAC)

      1. Early digital computer

      2. U.S. Army used it to compute World War II ballistic firing tables

      3. 18,000 Vacuum tubes

      4. ENIAC could add, subtract, multiply, divide, and calculate square roots

      5. ENIAC stored a maximum of twenty 10-digit decimal numbers

 

The Basics

 

  1. Digital Computer Basics

    1. Digital computers are essentially switches.

      1. Either ON or OFF

      2. On is 1 while OFF is 0

      3. Computer moves or manipulates data

      4. Example - 10101010

    2. Computer buses - computers process groups of digits

      1. Four bits is four on/off states

        1. Total of 16 combinations

        2. 24 = 16

      2. 32- bit microprocessor

        1. 232 = 4,294,967,296

        2. This number can be a color for a monitor, calculation on a spreadsheet, etc.

        3. Memory, graphics capability, etc. relate to the number of bits

      3. Currently, 64-bit microprocessor

        1. 264 = 18,446,744,073,709,551,616

    3. Technology

      1. Mechanical Computers

        1. Uses gears

        2. Large and slow

      2. Electrical Computers

        1. Relay Switches - a mechanical switch controlled by electricity

        2. Vacuum Tubes - similar to a light bulb, but can turn off and on

        3. Transistors (1947) - much smaller than a vacuum tube and uses less electricity

        4. Integrated Circuits (1958) - group of transistors on one computer chip

        5. Microprocessors (1971) - many transistors on one computer chip

  2. Moore’s Law - the number of transistors per square inch on integrated circuits would double every 18 months.

    1. Most experts expect

    2. Transistor Count

      1. Pentium            1993               3.1 million

      2. Pentium II        1997                7.5 million

      3. Pentium III      1999                 9.5 million

      4. Pentium IV      2000                 42 million

      5. Core 2 Duo     2006               291 million

    3. What happens if we hit the limit?

      1. The industry switches to multiple cores.

      2. Duo core - two computers on one chip

      3. Quad core - four computer on one chip

  3. Programming Languages - computer is taught logical English

    1. Humans have trouble thinking in computer code

    2. Compiler - translates English instructions into machine code

      1. Invented by Grace Hopper

      2. A goal is to design computer languages in a natural language

  4. Graphical User Interface (GUI)

    1. Xerox

      1. Mouse and graphical interface

      2. Developed by Xerox engineers in early 1970s

      3. Xerox management did not understood what they had

    2. Apple Computers

      1. Steve Jobs and Steve Wozniak started Apple Computers in their garage in California

      2. They stole the GUI from Xerox

      3. Implemented in the Lisa in 1983; too expensive and not successful

      4. Macintosh was extremely successful in 1984

    3. Microsoft

      1. Founded by Bill Gates in April 4, 1975

      2. Dropped out of college and wrote programs in Basic for the Altair 8800

      3. Stole the ideas of the GUI from Apple Computers

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