The Sinclair Executive calculator was the world's first slimline pocket calculator. It was released in 1972 and cost £79.95 +VAT. It was one third the size of any of its competitors in 1972 and cost half as much as it featured Texas Instrument's new TMS1802 "calculator-on-a-chip" IC which had been announced in September 1971.

Its small size was achieved by reducing the power input demanded by the TMS1802 chip that was used in the calculator by pulsing the current to the IC, reducing the power consumption by a factor of more than 10.

The calculator was capable of addition, subtraction, division and multiplication, and was able to store a constant.

The Sinclair Executive won a Design Council Award for Electronics in 1973.

There are two known versions of casing for the Sinclair Executive with different keyboard markings. This example in our collection is Type 1 which has a K (constant) two-way switch, rather than the button on the Type 2 version. On the Type 1 there is a decimal point switch on the right side of the calculator, which allows you to choose between Floating, 2, 3 and 4 decimal places, while the Type 2 is constantly set to floating point.

There are also at least five known variations of the Type 1 Executive calculator, including differences in LED display size, number of batteries required, and the chip. This example in our collection uses four button cells, and has the small LED display which uses bubble magnifiers. However, because the cases are glued shut we are unable to tell what chip is inside this model.

Manufacturer: Sinclair Radionics
Date: 1972

This exhibit has a reference ID of CH62672. Please quote this reference ID in any communication with the Centre for Computing History.

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