Wrist Calculator - Vintage Sinclair

Specifications:

Date: Feb. 1977
Cost new: £11
Cost today: £200 - £400
Scarcity: Very Rare.
Display : 8 digit Red LED
Functions : +, -, *, /, %, memory, square root
Power : 6 X watch batteries (8.1V)
IC: Mostek MK50321N
Size : 47 x 45 x 18 mm (1.9 x 1.75 x 0.7 ins).

Clive Sinclair loved to miniature everyday electronic items and this calculator on the wrist is a good example. Although watch-calculators were common, I believe only one other manufacturer made a pure wrist calculator. It used the same chip from the Sovereign calculator with a custom LED display. Came in self-assembly kit form only. There was also a later version with additional scientific functions. An unknown number were sold but they are amongst the rarest of Sinclair products today.

Thanks to www.vintagecalculators.com for the use of this photo.