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## History of digital computers

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**HISTORY of DIGITAL COMPUTERS**• Before Digital Computers • Early Systems • Contemporary systems**Before Digital Computers**• The Abacus • Napier’s Bones • Pascal’s Arithmetic Machine • Leibniz and the Stepped Reckoner • Jaquard’s Loom • Babbage’s Analytical Engine • Lady Lovelance • Boolean Logic • Hollerith’s Punched-Card Tabulating Machine • Powers and the Simultaneous Punching Machine**Bead at center**counts 5 counts 1 0 0 7 2 3 0 1 8 9 The Abacus • 3000 B.C. until now used by the Chinese**Napier’s Bones**• 1615 Scottish John Napier invented a computing device that facilitated multiplications and divisions • 1620 the principle was used to invent the first slide rule • The slide rule disappeared in the 1970’s by introducing the electronic calculator**Pascal’s Arithmetic Machine**• 1642 Blaise Pascal (19 years old) designed the Pascal’s arithmetic machine. • Via wheels and gears calculations were possible. • Principle nowadays still used in automobile odometers to record mileage. • The machine revealed to the public in 1645 was not a success because it required considerable skill to operate. • The machine performed +, -, *, /**Leibniz and the Stepped Reckoner**• 1673 Gottfried Leibniz modified Pascal’s machine to perform * and / more directly. • Multiplication was implemented automatically via a number of additions. Divisions via a number of subtractions. • The machine turned complex arithmetic into a series of steps involving simpler operations.**Jaquard’s Loom**• Major contribution to computer methods came from the weaving industry. • 1801 Joseph Marie Jacquard developed an attachment for weaving looms that used punched cards to “program” a loom to a specific pattern.**Babbage’s Analytical Engine**• 1830 Babbage worked on the Difference Machine which was abandoned in 1834 for the Analytical Engine. • The Analytical Engine was designed to have • a store to hold data and results of calculations • a mill was to be a central mechanism for performing mathematical operations • a systems of gears and levers was to transfer data back and forth between the store and the mill • the input/output unit was to read data from outside the machine into its store and display the results of the calculations • Effort stopped in 1842.**Lady Lovelance**• 1842 Augusta Ada Byron, Countess of Lovelance, daughter of the poet Lord Byron, translated a paper on Babbage’s Analytical engine from French to English. • She made so much notes and examples which were later considered as the first computer programs. • The ADA programming language is named after her.**Boolean Logic**• The application of the binary system to computers was facilitated by work performed in the mid 1800s by George Boole. • 1854 publishing of the Principles of Boolean logic**Hollerith’s Punched-Card Tabulating Machine (1)**• US census every 10 years. Manual treatment took 7 years if only heads were counted. • tabulation of social, ethnic and economic data would take 12 years to treat manually. • John Billing suggested the used of punched cards for recording the facts and a machine to treat them. • Herman Hollerith (Billings’s associate) made the design which was patented on March 31, 1884.**Hollerith’s Punched-Card Tabulating Machine (2)**• The census of 1890 used the machine and took only 2,5 years to complete. • Hollerith started the Tabulating Machine Company in 1896 which became the Computing-Tabulating-Recording Company after a series of mergers. • In 1924, under the leading of J. Watson, Sr. the company was renamed International Business Machines (IBM) which is now the largest computer company.**EARLY SYSTEMS**• Aiken and the Harvard Mark I • Atanasoff and the ABC • Mauchly, Eckert and the ENIAC • Von Neuman and the Stored Program Concept • Wilkes and the EDSAC • UNIVAC: the first commercial computer • IBM: the Giant Awakens**Aiken and the Harvard Mark I**• If Babbage had lived 75 years later, I would have been out of job. Howard Aiken • 1939 H. Aiken of Harvard University began working on a machine to perform scientific calculations faster. • IBM sponsored Aiken and the MARK I was completed in 1944 (IBM ASCC) • The first real computer was born. • the first general purpose digital electro-mechanical computer • The MARK I performed faithfully for 10 years.**Mark I**• 51 feet long, 8 feet high, 3 feet deep • weight: many tons • 3000 mechanical switches • 750.000 electronic components • 500 miles of wiring • Controlled by punched paper tape • Stored its numbers in mechanical switches • Used decimal numbers • Accuracy: 23 digits • 3 +/s, 1 * in 6 s, 1 / in 12 s**Atanasoff and the ABC**• 1942 John Vincent Atanasoff of Iowa State College and Clifford Berry (his graduate student) completed work on an electronic vacuum tube computer. • The Antony, Berry Computer (ABC) is the first electronic digital computer • Used the binary system • Designed for solving simultaneous equations**Mauchly, Eckert and the ENIAC**• John W. Mauchly of the University of Pennsylvania together with J. Presper Eckert, Jr. a graduate student, built the first electronic general purpose computer. • The Electronic Numerical Integrator and Computer (ENIAC) was funded by the U.S. Army as the need for computing accurate ballistic tables in WW II. • Completed in 1945.**ENIAC**• 1500 square feet of floor - 30 tons • 19.000 vacuum tubes • 500.000 soldered joints and no moving parts • Decimal arithmetic • in 1 sec: 5000 + or 300 * of 10 digit numbers • Needed a lot of power • Big problem to keep the machine working (vacuum tubes were relatively short-lived)**ENIAC**150MHz Pentium Speed 5,000 additions / second 300,000,000 Memory 200 digits 16,000,000 Elements 18,000 vacuum tubes 6,000 switches 10,000 capcitors 70,000 resistors 1,500 relays 4,000,000 transistors (CPU) Size 10 feet tall x 1,800 square feet 9" x 12" x 3" Weight 30 tons 6 pounds**Von Neuman and the Stored Program Concept**• 1946: John von Neumann joined Mauchly & Eckert and began working on an improved version of the ENIAC called EDVAC (Electronic Discrete Variable Automatic Computer). • von Neumann proposed that the program as well as the data it operated should be stored in the computer’s memory • perform a program from memory is much faster than performing it from punched cards. • This is one of the most important developments in the computer field in the 1900s**Wilkes and the EDSAC**• 1949 (before EDVAC) the first stored program computer was developed by Maurice Wilkes at the University of Cambridge in England: EDSAC (Electronic Delay Storage Automatic Calculator) • As soon as we started programming, we found to our surprise that is wasn’t as easy to get programs right as we had thought. Debugging had to be discovered. I can remember the exact instance when i realized that a large part of my life from then on was going to be spent in finding mistakes in my own program. • M. Wilkes at the opening of the Digital Computer Museum in Marlboro, Massachusetts (now in Boston) in 1979.**UNIVAC: the first commercial computer**• 1946: Echert and Mauchly left the University of Pennsylvania to form Eckert-Mauchly Computer Corporation which was acquired by Remington Rand three years later. • Remington Rand intended for commercial data processing systems. • They delivered a computer called UNIVAC I in 1951 at the Bureau of Census in the US. • The computer was used reliably until 1963. • The UNIVAC I computer was used in 1952 to predict the election of Eisenhower with only 3 percent of the popular vote counted.