HPS202 Lecture 18: Computing Before Computers

Early Aids to Calculation

• Human; Finger counting and reckoning
• Abacus; unknown origin, not Oriental, still common in Europe until 17th century.
• Quadrant; quarter circle tool for measuring altitudes
• Napier's Bones; John Napier (1550-1617) inspired by gelosia method; bones are collection of gelosia strips to simplify multi-digit multiplication; 19th century: Genaille-Lucas rulers simplified further
• Logarithms; invented by Napier; simplified trigonometric and geometric calculations
• Slide-rules; adapted from logarithms 17th century, not popular until 20th

Mechanical Calculating Machines

• Wilhelm Schickard (1592-1635); German polymath; 1623: first known description of mechanical calculator for multiplication
• Blaise Pascal (1623-1662); French mathematician and philosopher; 1642: mechanical addition and subtraction
• Gottfried Wilhelm Leibniz (1646-1716): German mathematician and philosopher; attempted modification of Pascal machine, in early 1670s invented his own mechanical multi-digit multiplication
• Others: 1820s, M. Charles Xavier Thomas de Colmar's arithmometer; 1880s, Dorr E. Felt's Comptometer; 1890s, William S. Burroughs' adding and printing machine

Babbage and his Engines

• O.E.D.: One who computes; a calculator, reckoner; spec. a person employed to make calculations in an observatory, in surveying, etc
• General purpose and special purpose tables; 1766 Nautical Almanac; Division of labour used by Baron Gaspard de Prony to generate metric conversions in 1790s
• Charles Babbage (1791-1871) inspired by de Prony and problem of table errors to build a mechanical tabulator
• Difference Engine: generality that a polynomial equation F(x) can be evaluated by noting the differences between adjacent values of x; 1822 prototype completed to raise government funds; 1833 second prototype finished but attention diverted
• Analytical Engine intended as universal mathematical machine, capable of much more functions; included printer; never built by Babbage

Cash Registers

• National Cash Register Company founded by John H. Patterson (1844-1922); N.C.R. dominated industry
• N.C.R. connections to computing: (1) one of oldest computer companies; (2) Thomas Watson Sr. (1874-1956), first president of I.B.M learned his trade at N.C.R