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The devices that ended the three hundred year supremacy of the
logarithm table. Early examples were comparatively power hungry
and had a very limited battery life. They were frequently used
with mains adaptors. The development of low power integrated
circuits and in particular, liquid crystal displays meant that
calculators at last became truly portable.
Top row, from left to right
- Rockwell 24RD-II - (1976). Six functions (+
- × ÷ % √). This has a 9 digit fluorescent
display and is powered by three AA size dry cells. These give a
useful lifetime of between three and five hours.
- Sinclair Scientific An early scientific
calculator by Clive Sinclair. Four arithmetic functions (+ -
× ÷) and additionally, log, sin, cos, tan and their
inverses. This calculator is dry cell powered and has 9 digit LED
- Texas Instruments TI-55-II - (1981). A
programmable scientific calculator, with liquid crystal display.
This has up to eight user memories (0-7) and up to 56 program
steps Program and data memory is shared and every eight program
steps take up one user memory, starting at 7 and working back
towards 1. Memory location 0 cannot be used for programming. The
calculator is powered by two button cells. These retain the
contents of memory when the calculator is switched off and last
at least a year.
- Texas Instruments SR-51A - (1974). An early
scientific calculator with a fourteen digit LED display. This has
a built-in rechargeable battery pack, which gives a usable life
of about three hours. The calculator has three addressable
memories and limited statistical functions, mean, standard
deviation, linear regression. I bought this particular example in
the early 1970s when it cost about £70.
Front row - some novelties - left to right:
- A credit card sized disposable solar powered
calculator - (1999). Six functions (+ - × ÷
% √). This calculator is approximately one eighth of an
inch (3mm) thick and has a nine digit liquid crystal display. It
is a good illustration of the changes that have taken place since
the 1970s, being about the same size and weighing little more
than the cover of the battery compartment of the
Rockwell 24RD-II described above.
- Casio AQ-2200 - (1982). A six function
calculator (+ - × ÷ % √) with additional
calendar and timer functions (clock, alarm clock,
- A novelty "book match" calculator - (1989).
A calculator disguised as a pack of matches. Open the pack and
the keys are printed inside the card cover.
||A final word ...
Hyper intelligent beings don't need calculators.
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