Sinclair Executive

The Executive was launched in September 1972 at the price of plus VAT, equivalent to £ in when adjusted for inflation. This was around half the price of comparable calculators, but still twice the average weekly wage. It was the first pocket calculator, and the first to be mass-produced, and its introduction to the market coincided with a number of other companies entering the calculator market. The entrepreneur Clive Sinclair, reckoning that the market for "executive toys" was not especially sensitive to price, ordered components for 100,000 calculators. The parts, consisting of the TMS1802 chip, 22 transistors, 50 resistors and 17 capacitors, cost close to , compared with a sale price of almost . A Sinclair Executive purchased by a Russian diplomat exploded in his breast pocket, allegedly leading to an official Soviet investigation. It was found that it had been left on by accident, leading to a drain on the batteries that overheated them until they burst. ==Design==

The calculator was significantly smaller than any of its competitors, and the first that could easily be carried in a pocket. The Executive weighed and measured . The case, designed by Iain Sinclair, was made of black injection-moulded polycarbonate and required flexible glue to hold the two halves together. It was the first calculator designed for aesthetic appeal, and New Scientist described it as "not so much a professional calculator – more a piece of personal jewellery". The Executive could display results to two, four, or six decimal places, or use a floating decimal point. Microprocessor The calculator was powered by a Texas Instruments TMC1802NC, a metal oxide semiconductor integrated circuit with 7,000 transistors. Power is supplied to the chip in 1.7-microsecond pulses as determined by the storage time of a control transistor. An oscillator clock operating at 200 kilohertz during calculations and dropping to 15 kHz between each operation means shut-off time ranges from 3.3 microseconds during calculations to more than 65 microseconds between. The small screen reduced the power consumption and material costs, but it was revised several times in pursuit of lower power consumption, creating reliability problems. == Successors ==

The Executive Memory was launched in November 1973, with the same dimensions as the original, but with the ability to memorise subtotals from any number of chain calculations. There were at least three versions, including the black and white Type 1, and the Type 2 with a gold keyboard. ==References==