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History of Computers - Software.
In the early days of computing the control part was all done by hand.
The slow desk computers were at first controlled by hand, for example
multiplication was done by repeated additions, with column shifting
after each digit of the multiplier. Division was similarly done by
repeated subtractions. In time electric motors were applied both for
power and later for more automatic control over multiplication and
division. The punch card machines were controlled by plug board
wiring to tell the machine where to find the information, what to
do with it, and where to put the answers on the cards (or on the
printed sheet of a tabulator) , but some of the control might also
come from the cards themselves, typically X and Y punches,
(other digits could, at times, control what happened).
A plug board was usually specially wired for each job to be done,
and saved and used again each week, or month, as they were needed
in the cycle of accounting.
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