Sinclair Wrist Calculator
Sinclair Wrist Calculator
Display is 8 digits, red LED.
4-functions, %, memory, square root.
8.1v (6x mercury cells).
Integrated circuit - Mostek MK50321N, here date coded mid-1976.
47 x 45 x 18 mm (1.9 x 1.75 x 0.7 ins).
Made in England.
1977.
Was available only as a self-assembly kit, by mail order from Science of Cambridge, previously Sinclair Instrument Ltd.
There appear to be two versions of this calculator, see photograph below.
Total price was £11Sterling (about US$20).
Although several companies made combined watch-calculators, such as the Compuchron, only Sinclair made a purely wrist calculator.
Clive Sinclair was always interested in making tiny versions of common electronic items. Here, into the smallest practical volume he managed to squeeze the LED display and chip used in other Sinclair calculators (the Sinclair Cambridge Memory and Cambridge Universal), which were then becoming obsolescent.
