Sinclair Executive

Sinclair Executive
Sinclair Executive Type 1
IntroducedSeptember 1972
Invented byClive Sinclair
Display typeLight-emitting diode
Display size8 digits
ProcessorTexas Instruments TMS1802NC[1][2]
Frequency200 kHz
Power supply4 button cells
Power consumption20 milliwatts
Dimensions56 by 138 by 9 millimetres (2.20 in × 5.43 in × 0.35 in)

The Sinclair Executive was the world's first "slimline" pocket calculator, and the first to be produced by Clive Sinclair's company Sinclair Radionics. Introduced in 1972, there were at least two different versions of the Sinclair Executive, with different keyboard markings, and another called the Sinclair Executive Memory, introduced in 1973.

Its small size was made possible by pulsing the current to the Texas Instruments TMS1802 "calculator on a chip" integrated circuit, reducing the power consumption by a factor of more than 10. The Executive was highly successful, making GB£1.8 million of profit for Sinclair and winning a Design Council Award for Electronics.


The Executive was launched in September 1972 at the price of GB£79.95 plus VAT, equivalent to £970 in 2016 when adjusted for inflation. This was around half the price of comparable calculators, but still twice the average weekly wage.[3][4][5] 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.[5][6]

Clive Sinclair, reckoning that the market for "executive toys" was not especially sensitive to price, ordered components for 100,000 calculators.[7] The Executive was highly successful, and made 1.8 million pounds profit for Sinclair Radionics.[8] It was well received by both domestic and foreign markets, and US$1.5 million worth of Executives were sold in Japan in early 1974 at six times the price of Japanese models.[9] The parts, consisting of the TMS1802 chip, 22 transistors, 50 resistors and 17 capacitors, cost close to GB£10, compared with a sale price of close to GB£80.[10] The Executive impressed the engineers at Texas Instruments, who had used the same chip to produce a longer and wider calculator that was over three times as thick and a great deal more expensive.[10] In 1974, sales of the Executive were greater than GB£2.5 million, and Sinclair was producing 100,000 calculators each month, of which 55% were exported.[11]

A Sinclair Executive purchased by a Russian diplomat exploded in his breast pocket, allegedly leading to an official Soviet investigation.[12] It was found that it had been left on by accident, leading to a current drain on the batteries that overheated them until they burst.[13]