Chapter6.docx

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Department
Computer Science
Course
CMPT 120L-115
Professor
Matthew Johnson
Semester
Fall

Description
A Balanced Introduction to Computer Science, 3 Edition rd David Reed Chapter Six: The History of Computers A. Generation 0: Mechanical Computers (1642-1945) 1. 1600s: century of genius a. Galileo, Kepler, Fermat, Leibniz, Boyle, and Newton laid the foundation for modern science by defining a rigorous and methodical approach to technical investigation based on a belief in unalterable natural laws i. Increased interest in science andmath b. William Schickard: 1 calculator (1623) i. Lost in a fire c. Blaise Pascal: 1 prototype of a calculator (1642) i. Gottfried Wilhelm von Leibniz (1672) expanded this to include multiplication and division d. The precision required for a working calculator made it difficult to build at the time i. 1820: Thomas de Colmar made a variation of Leibniz’s calculator 2. Programmable Devices st a. Joseph-Marie Jacquard invented the 1 programmable machine (a loom) in 1801 i. Stored the patterns as holes punched in cards b. Charles Babbage used this idea for the design of his Difference Engine (steam-powered mechanical calculator for solving mathematical equations) 1821 i. A prototype was built, but never a fully function model ii. Envisioned expanding to an Analytical Engine (like modern computers) iii. The store would hold data/programs and a control unit (the mill) c. Ada Byron supported the Analytical Engine- had extensive notes on it (step-by-step instructions for the machine) i. She was considered the 1 programmer 3. Electromagnetic Relays – mechanical switch that can be used to control the flow of electricity through a wire a. A magnet attached to a metal arm i. The arm is open (interrupting electrical flow) until current is applied to a control wire and he magnet pulls the arm closed b. Used in early telephone exchanges c. 1930s: began to be used to define the logic of a computer i. Konrad Zuse: 1 relay-powered computer ii. John Atanasoff and George Stibitz indepently made computers with electromagnetic relays d. Howard Aiken used Babbage’s designs to make modern technology i. Mark I computers (1944) ii. Made complete complex calculations B. Generation 1: Vacuum Tubes (1945-1954) 1. Electromagnetic relays made computer speeds limited by the inertia of moving parts 2. Vacuum tubes – small glass tubes from which all or most of the gas has been removed, allowing electrons to move with minimal interference a. replaced electromagnetic relays in mid 1940s b. worked faster than electromagnetic relays 3. Computing and WWII a. Alan Turing: 1 electronic computer, COLOSSUS to decode Nazi communications i. Had over 2,300 vacuum tubes b. John Maunchly and J. Presper Eckert built an electronic computer, the ENIAC i. Computed ballistics table for the US Army (1946) ii. Performed complex challenges 4. von Neumann Architecture a. John von Neumann: designed computer architecture in which programs could be stored in memory along with data i. Replaced witches and cables b. This architecture focused on how computers were programmed, not designed c. Programs were first written in machine languages (0 and 1) i. Corresponded to instructions executed by the hardware d. Assembly languages (1950s) simplified the act of programming by substituting mnemonic names for binary numbers e. Eckert Mauchly Computer Corporation sold commercial computers (1951) i. UNIVAC I C. Generation 2: Transistors (1954-1963) 1. John Bardeeny, Walter Brattain, and William Sh
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