Pascal's calculator Jacquard's loom Babbage's Difference Engine Hollerith's machine electromagnetic relay

Pascal's calculator
Jacquard's loom
Babbage's Difference
Engine
Hollerith's machine
electromagnetic
relay
A Balanced Introduction to Computer Science and Programming
David Reed
Creighton University
Copyright © 2004 by Prentice Hall
Chapter 6: The History of Computers
Where a calculator on the ENIAC is equipped with 18,000 vacuum tubes and weighs 30 tons, computers in the future may have only 1,000 vacuum tubes and weigh only 1 1/2 tons.
Popular Mechanics, 1949
Never trust a computer you can't lift.
Stan Mazor, 1970
If the automobile had followed the same development cycle as the computer, a Rolls-Royce would today cost $100, get one million miles to the gallon, and explode once a year, killing
everyone inside.
Robert X. Cringely
Computers are such an integral part of our society that it is sometimes difficult to imagine life without them. However, computers as we know them are relatively new devices, with the first electronic computers dating back to the s. Since that time, technology has advanced at an astounding rate, with the capacity and speed of computers approximately doubling every two years. Today, pocket calculators have many times the memory capacity and processing power of the mammoth computers of the sand 1960's.
This chapter presents an overview of the history of computers and computer technology. The history of computers can be divided into generations, roughly defined by technological advances that led to improvements in design, efficiency, and ease of use.
Generation 0: Mechanical Computers (1642-1945)
The first working calculating machine was invented in 1623 by German inventor Wilhelm Schickard (1592-1635), although details of its design were lost in afire soon after its construction. In 1642, the French scientist Blaise Pascal (1623-1635) built a mechanical calculator when he was only 19. His machine used mechanical gears and was powered by hand. A
person could enter numbers up to eight digits long using dials and then turn a crank to either add or subtract. Thirty years later, the German mathematician Gottfried Wilhelm von Leibniz) generalized the work of Pascal to build a mechanical calculator that could also multiply and divide. A variation of Leibniz's calculator, built by Thomas de Colmar (1785-
1870) in 1820, was widely used throughout the 19th century.
While mechanical calculators grew in popularity in the early s, the first programmable machine built was not a calculator at all, but a loom. Around Frenchman Joseph-Marie Jacquard (1752-1834) invented a programmable loom that used removable punched cards to represent patterns. Before Jacquard's loom, producing tapestries was complex and tedious work. In order to produce a pattern, different colored threads (called wefts) had to be woven over and under the cross-threads (called warps) to produce the desired effect.
Jacquard devised away of encoding the patterns of the threads using metal cards with holes punched in them. When a card was fed through the machine, hooks passed through the holes to selectively raise warp threads, and so produce the desired over-and-under pattern. The result was that complex brocades could be encoded using the cards, and then reproduced exactly. Simply by changing the cards, the same loom could be used to automatically weave different patterns.
The idea of using punched cards for storing data was adopted in the mid s by the English mathematician Charles Babbage (1791-1871). In 1821, he proposed the design of his Difference Engine, a steam-powered mechanical calculator for finding the solutions to polynomial equations. Although a fully functional model was never completed due to limitations in 19th century manufacturing technology, a prototype that punched output onto copper plates was built and used in computing data for naval navigation. Babbage's work with the Difference Engine led to his design in 1833 of a more powerful machine that included many of the features of modern computers. His Analytical Engine was to be a general-purpose, programmable computer that accepted input via punched cards and printed its output on paper. Similar to the design of modern computers, the Analytical Engine was to be made of integrated components, including a readable/writeable memory for storing data and programs (which Babbage called the
store), and a control unit for fetching and executing instructions (which he called the mill). Although a working model of the Analytical Engine was never completed, its innovative and visionary design was popularized by the writings and patronage of Augusta Ada Byron, Countess of Lovelace (Punch cards resurfaced in the late sin the form of Herman Hollerith's tabulating machine. Hollerith invented a machine for sorting and tabulating data for the 1890 US. Census.
His machine utilized punch cards to represent census data, with specific holes on the cards representing specific information (such as male/female, age, home state, etc) Recall that in
Jacquard's loom, the holes in punch cards allowed hooks to selectively pass through and raise waft threads. In the case of Hollerith's tabulating machine, metal pegs passed through holes in the cards, making an electrical connection with a plate below that could be sensed by the machine. By specifying the desired pattern of holes, the machine could sort or count all of the cards corresponding to people with given characteristics (such as all men, aged 30-40, from Maryland. Using Hollerith's tabulating machine, the 1890 census was completed in six weeks (compared to the 7 years required for the 1880 census. Hollerith founded the Tabulating Machine Company into market his machine. Eventually, under the leadership of Thomas J. Watson, Sr, Hollerith's company would become known as International Business Machines (IBM).
It wasn't until the sand the advent of electromagnetic relays that computer technology really started to develop. An electromagnetic relay is a mechanical switch that can be opened and closed by an electrical current that magnetizes it. The German engineer Konrad Zuse (1910-1995) is credited with building the first computer using relays in the late
1930's. However, his work was classified by the German government and eventually destroyed during World War II, and so did not influence other researchers. In the late s, John Atanasoff
(1903-1995) at Iowa State and George Stibitz (1904-1995) at Bell Labs independently designed and built automatic calculators using electromagnetic relays. In the early s, Howard Aiken) at Harvard rediscovered the work of Babbage and began applying some of Babbage's ideas to modern technology. Aiken's Mark I, builtin, maybe seen as an implementation of Babbage's Analytical Engine using relays.
In comparison with modern computers, the speed and computational power of these early computers may seem primitive. For example, the Mark I computer could store only 72 numbers in memory, although it could store an additional 60 constants through manual switches. The machine could perform 10 additions per second, but required up to 6 seconds to perform a multiplication and 12 seconds to perform a division. Still, it was estimated that complex calculations could be completed 100 times faster using the Mark I as opposed to existing technology at the time.