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Sinclair Scientific
1975-77


Size: 50 mm x 111 mm x 19 mm (Scientific)

73 mm x 155 mm x 34 mm (Scientific Programmable)

Display: 7 digits, red LED

Power: 4V (4 x AAA batteries) (Scientific)

9V (PP3 battery) (Scientific Programmable)


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The Sinclair Scientific, launched in August 1975, was a highly unusual calculator. It displays only in scientific notation - 5 digit mantissa, 2 digit exponent. Because of the way its processor (a custom chip from Texas Instruments) is designed, it relies on reverse Polish notation. This unusual method of mathematical problem solving meant that, for instance, to add 2 and 4, one had to enter 2, then 4, then the + symbol. There was no = key.

The Scientific Programmable was an advanced version launched in 1977, again using reverse Polish notation. It could handle programs of up to 24 steps and cost £29.95.

The Scientific Programmable Mark 2 was powered either by a 9V battery or a mains adaptor and cost £17.22. It came with twelve sample programs, with another 294 contained in an additional four-volume library which could be bought for £4.95. Each volume was dedicated to a different application: finance and statistics, mathematics, physics and engineering, and electronics.


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Chris Owen 1994-2003