- 1820
- Charles Xavier Thomas de Colmar (1785-1870), of France, makes his
"Arithmometer", the first mass-produced calculator.
- 1822
- Charles Babbage (1792-1871), of London, having reinvented the
difference engine, begins his (government-funded) project to build one by
constructing a 6-digit calculator using similar geared technology.
- 1832
- Babbage produces a prototype segment of his difference engine,
which operates on 6-digit numbers and 2nd-order differences (i.e.
can tabulate quadratic polynomials). The complete engine was to have
operated on 20-digit numbers and 6th-order difference, but no more than
this prototype piece was ever assembled.
- 1834
- Pehr George Scheutz, Stockholm, produces a small difference engine
in wood, after reading a brief description of Babbage's project.
- 1836
- Babbage produces the first design for his "Analytical Engine".
Whether this machine, if built, would have been a computer or not
depends on how you define "computer". It lacked the "stored-program"
concept necessary for implementing a compiler; the program was in read-only
memory, specifically in the form of punch cards. In this article such a
machine will be called a "program-controlled calculator".
The final design had three punch card readers for programs and data.
The memory had 50 40-digit words of memory and 2 accumulators. Its
programmability included the conditional-jump concept. It also included a form of
microcoding: the meaning of instructions depended on the positioning of
metal studs in a slotted barrel. It would have done an addition in
3 seconds and a multiplication or division in 2-4 minutes.
- 1842
- Babbage's difference engine project is officially cancelled.
(Babbage was spending too much time on the Analytical Engine.)
- 1843
- Scheutz and his son Edvard Scheutz produce a 3rd-order difference
engine with printer, and the Swedish government agrees to fund
their next development.
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