1972 · Slimline Pocket Calculator · Work 939 of 1,871
The cutting room of a gentlemen's tailor in London, a dark grey pinstripe jacket on a wooden hanger, a hand with a white shirt cuff and a silver cufflink drawing from its inside pocket a very flat calculator fourteen centimetres long and one centimetre thin, a narrow bar of matt black plastic with a faint blue sheen, at its upper end a dark red window with a small soft red glow, below it small square black keys recessed in the black surface, all plain smooth and unmarked, a black leather wallet and tailor's chalk on the cutting table, bolts of grey and navy wool on shelves behind, soft daylight from a tall window.
What it was used for
Sinclair Radionics sold the Executive, a slim pocket calculator, from 1972 at 79.95 pounds plus tax; according to the Centre for Computing History that was about half the price of the competition, and the machine was 1 third the size of comparable calculators of 1972. It did the 4 basic operations, could hold one constant, and had a switch setting the decimal point to floating or 2, 3 or 4 places. The LED display was small and read through magnifying lenses. The museum's example runs on 4 button cells. In 1973 the Executive received the Design Council Award for Electronics.
What was new
The calculating device came from Texas Instruments: the TMS1802, a "calculator-on-a-chip" announced in September 1971. What marked the Executive was its power regime. Sinclair pulsed the supply to the chip instead of feeding it continuously and cut current draw, in the words of the Centre for Computing History, by more than a factor of 10; the machine's small size rested on that. The cases are glued shut, so on this example it cannot even be checked which chip is inside. There are at least 5 variants of the Type 1, differing among other things in the number of cells.
What the sources leave open: Only 1 source, the Centre for Computing History; it gives neither dimensions nor weight and cannot confirm the chip in the example. That the Executive was the world's first slimline pocket calculator is that page's statement, not independently checked.