The Film Card

1983 · Solar Card Calculator · Work 957 of 1,871

A hotel room desk in Tokyo at night, an open wallet of soft brown leather under a brass desk lamp, a hand in a dark suit sleeve drawing from one of its pockets a wafer-thin solar calculator eight and a half by five and a half centimetres, a smooth silver-grey card with rounded corners, at its upper left a small dark display window, at its upper right a dark solar strip of four narrow bands, below them a flat grid of twenty-four faint square fields, the whole surface plain, smooth and unmarked, a heavy brass room key and a glass of water beside the wallet, blurred city lights in the dark window.

What it was used for
According to Casio's own corporate history the SL-800 "Film Card" appeared in November 1983: a credit-card-sized calculator only 0.8 mm thick. The Centre for Computing History gives 85 x 54 x 0.8 mm and 12 g. It calculated to 8 digits on liquid crystal, with square root, percent and one memory; power came, according to the Casio Calculator Museum, from an amorphous-silicon cell that sufficed from about 150 lux. The same source gives the retail price as 5,900 yen. The Centre for Computing History reckons the device at about 0.07 per cent of the weight and about 0.008 per cent of the volume of Casio's first calculator, the Model 001.
What was new
What marked it was the construction: the electronics sat on film, and the Centre for Computing History says this film technology contributed to Casio's further miniaturisation. The barb is in the production record: according to the Casio Calculator Museum the SL-800 was made only from November 1983 to September 1984, about 11 months.

What the sources leave open: Month and thickness come from Casio's own corporate history, dimensions, weight and the comparison from the Centre for Computing History, whose text is taken from the Casio Calculator Museum. No source claims a priority. Solar cell, lux figure, price and production period come from the Casio Calculator Museum, a private collector's site. The Computer History Museum's catalogue record dates the same model to 1978; that figure stands against Casio itself and is not used here.

Further reading