Sinclair Cambridge Memory electronic calculator, 1974.
© Science Museum / Science & Society Picture Library
This was one of a series of pocket calculators introduced by Clive Sinclair in the early 1970s, beginning with the 'Executive' in 1972. Sinclair was able to make a calculator small and light enough to put in the pocket by reducing the power input demanded by the calculator chip. The calculator was not only much smaller and thinner than its competitors, but also much cheaper. The case is made of plastic and it has an 8 digit, red LED (light-emitting diode) display.