The Abacus

• At least 5,000 years old
• Memory aid for making mental calculations
• Not a true mechanical calculating machine
• Eventually replaced by pencil and paper

• French mathematician
• Built the first mechanical adding machine in 1642 (the Pascalene)

• Invented Jacquard loom in 1801
• Fabric patterns controlled by punched cards
• Could produce fabrics faster and more accurately than any human
• Knowledge stored in cards could be spread easily
• Machine could be tended by unskilled factory workers
• Caused riots in 1811 by skilled craftsmen fearing for their jobs (the Luddites)

• English mathematician and inventor
• Frustrated by errors in mathematical and navigation tables
• Produced prototype of Difference Engine in 1822
• Used clockwork technology (wheels, cogs, and shafts)
• Designed to solve polynomial equations (e.g., 3.56x⁷ - 7.6x³ + 2.39x - 8.94 = 0)
• Never completed
• Working version built in 1991 at the Science Museum of London using only technology available in Babbage's time

• Difference Engine inspired Babbage to design the Analytical Engine in 1833
• Steam-powered design
• General-purpose programmable machine
• Designed to store 1000 numbers of 50 decimal digits each
• Composed of several devices:
  • one to receive instructions coded on punched cards (like Jacquard loom)
  • one to perform the coded instructions
  • one to store results of intermediate calculations
  • one to print out information on paper
• Virtually identical in design to a modern computer
• Never built

• Daughter of Lord Byron
• Babbage's patron, assistant, and chronicler
• Wrote sets of instructions for the Analytical Engine
• World's first computer programmer
• U.S. Department of Defense named its programming language Ada after her
• "The Analytical Engine weaves algebraic patterns just as the Jacquard loom weaves flowers and leaves"

• Developed a tabulating machine to process U.S. census information from punched cards in 1890
• Stacks of punched cards could serve as a permanent memory
• Cut census time from 10+ years to 6 weeks
• Not programmable
• Started a company to market his machine which merged with two others to form the Computing-Tabulating-Recording Company

• American physicist
• Built ABC machine with Clifford Berry in late 1930s at Iowa State College
• Special-purpose calculator for finding solutions to systems of equations
• All-electronic design used vacuum tubes for switching elements
• Never completed, due to insufficient funding

• German engineer
• Built Z1, Z2, Z3, and Z4 in late 1930s and early 1940s with Helmut Schreyer
• Electromechanical design used relays for switching elements
• General-purpose computing device
• Controlled by perforated celluloid strips (like punched cards)
• First machine to use binary number system
• Never completed, due to insufficient funding from the Nazi government

• American physicist and applied mathematician
• Built Harvard Mark I in collaboration with Grace Hopper and IBM engineers in 1944
• Inspired by Babbage's Analytical Engine
• Electromechanical design used relays for switching elements
• Handled 23-digit numbers, logarithms, trigonometric functions
• Controlled by punched paper tape
• Fully automatic but slow (3-5 seconds per multiplication)
• Remained in use at Harvard until 1959
• Grace Hopper found first actual computer bug while working on Mark II in 1945

• English mathematician and first true computer scientist
• Described mathematical model of a computer in 1936 (Turing Machine)
• Proved fundamental theorems about the limitations of computers
• Founded the field of Artificial Intelligence in 1950
• Wrote seminal papers in other fields (self-organizing chemical reactions)
• Helped break secret German Enigma codes in World War II [simulator]
• Worked on British electronic code-breaking computer called Colossus
• Enabled Allies to read German military transmissions from 1942 on
• Persecuted by British government for being homosexual
• Committed suicide in 1954

• Electronic Numerical Integrator And Calculator
• Developed by John Mauchly and J. Presper Eckert at the University of Pennsylvania in 1945
• First general-purpose all-electronic digital computer
• Reprogramming required physically rewiring the machine
• Used 19,000 vacuum tubes
• Filled a 30-by-50-foot room, weighed 30 tons, and dissipated 150,000 watts of energy
• Performed calculations for the atomic bomb project at Los Alamos

• Hungarian mathematician, computer scientist, cyberneticist, all-around genius
• Worked on atomic bomb project during World War II
• Invented game theory and developed the theory of self-replicating automata
• Originated key concept of stored-program computer in 1945
• Program instructions stored in memory along with data (program = data)
• Easily reprogrammable
• Von Neumann computer architecture became universal standard
• First stored-program electronic computers appeared in 1947

• Electronic Discrete Variable Automatic Computer
• Designed by Mauchly, Eckert, and Von Neumann
• Stored-program design
• Used binary instead of decimal words

• Stored-program computers with random access memory (RAM) of ~1000 words
• Used vacuum tubes (but took up much less space than ENIAC)
• Punched cards for input and output
• Vacuum tube memory or magnetic core memory for data storage
• Programmed directly in binary machine language
• Included EDVAC and UNIVAC (first commercially available computers)

• Invented at Bell Labs in 1947 by William Shockley, John Bardeen, and Walter Brattain
• Generated far less heat than vacuum tubes
• Required far less power than tubes
• Much smaller, faster, cheaper, and more reliable than tubes
• Incorporated into Second Generation computers (late 50s - mid 60s)

• Invented in late 1950s by Jack Kilby of Texas Instruments
• Many transistors etched on a single silicon chip as a single circuit
• Faster due to decreased distance between transistors
• Incorporated into Third Generation computers (mid 60s - early 70s)

• Thousands or millions of transistors per chip
• Incorporated into Fourth Generation computers (early 70s - present)

• Programming in binary machine language very tedious and difficult
• First compiler written in 1952 by Grace Hopper
• FORTRAN developed by John Backus and a team of IBM programmers in 1957
• ALGOL developed in 1958
• COBOL developed in 1959 by Grace Hopper
• LISP developed by John McCarthy at MIT in 1958
• BASIC developed in 1964 by Thomas Kurtz and John Kemeny at Dartmouth
• Pascal developed by Niklaus Wirth in 1968
• Prolog developed by Alain Colmerauer and Phillip Roussel in 1972
• C developed by Brian Kernighan and Dennis Ritchie at Bell Labs in early 1970s
• Ada developed by U.S. DOD in early 1980s (named in honor of Lady Lovelace)
• Java developed in 1990s by Sun Microsystems

• First microprocessor, the Intel 4004, released in 1971
• Designed by Ted Hoff for Japanese calculator company Busicom
• Followed by Intel 8008 and 4040 (1972) and 8080 (1974)
• Entire computer packaged as a single integrated circuit chip
• Equivalent to having an Analytical Engine the size of a shirt button
• Motorola 6800 (1974)
• MOS Technology 6502 (1975)
• Zilog Z80 (1976)

• First popular and affordable microcomputer (~$375)
• Based on Intel 8080 chip
• Some assembly required
• No software available
• 256 bytes of RAM
• Programmed by manually flipping switches on front panel
• Bill Gates and Paul Allen promised MITS a BASIC interpreter for the Altair, leading to the creation of Microsoft in 1975

• IMSAI 8080 was another microcomputer similar to the Altair 8800
• Doug Engelbart invented mouse at SRI in 1964
• Xerox PARC Alto computer (1974) used mouse, graphics, menus, icons
• Apple Computer founded in 1976 by Steve Jobs and Steve Wozniak
• Apple I based on 6502 chip
• Apple II had color graphics, BASIC, 4K RAM, cassette tape data storage ($1300)
• Apple Computer's sales went from $2.5M to $583M in six years (Fortune 500 by 1982)
• Radio Shack TRS-80 [2] introduced in 1977 (Z80 chip, 4K RAM, $600)
• Commodore PET introduced in 1977 (6502 chip, 4K RAM, $600)
• VisiCalc for Apple II released in 1979
• Steve Jobs visits Xerox PARC in 1979; inspired to develop Macintosh
• IBM PC introduced in 1981
• Apple Macintosh [2] introduced in 1984; first microcomputer with GUI
• Dell Computer founded by Michael Dell in 1984
• Compaq reverse-engineers IBM PC BIOS to produce first PC clone
• Steve Jobs quits Apple in 1985 to found NeXT Computer, Inc.

• ARPANET created in 1969 by connecting together 4 computers at UCSB, UCLA, Utah, and SRI
• World Wide Web developed at CERN in Switzerland by Tim Berners-Lee in late 1980s
• First Web browser written in 1990 by Tim Berners-Lee using a NeXT computer
• Marc Andreesen and Eric Bina at U. of Illinois develop Mosaic Web browser
• Marc Andreesen and Jim Clark found Netscape Communications in 1994
• Netscape goes public on August 9, 1995; worth $3 billion by the end of the day

• "I think there is a world market for maybe five computers"
  —Thomas Watson, Chairman of IBM, 1943

• "If automotive technology had progressed as fast as computer technology between 1960 and today, the car today would have an engine less than a tenth of an inch across, would get 120,000 miles per gallon, have a top speed of 240,000 miles per hour, and would cost $4"
  —Rick Decker and Stuart Hirshfield, The Analytical Engine

For Further Reading

The best available history of the personal computer revolution is
Fire in the Valley: The Making of the Personal Computer (2nd Edition)
by Paul Freiberger and Michael Swaine