Dead-flesh keys

When the ZX Spectrum was unveiled, on 23 April 1982, at the Churchill Hotel in London, there was a surprise. A pre-launch brochure showed grey keys of hard plastic, like a calculator's, but they belonged only to a mock-up used in the photographs. The machines that reached buyers had rubber keys, and their feel was described at the time, unkindly, as "dead flesh" ^[1].

The keyboard was the idea of Rick Dickinson, Sinclair Research's industrial designer, who had joined the company before even finishing his course at Newcastle Polytechnic and had already designed the ZX80 and ZX81 ^[3]. Sketches for the Spectrum case began in early August 1981, still with an angular wedge shape inherited from the ZX81; by mid-September they already showed the flatter design, with the raised back and rounded sides, that was eventually manufactured. The keyboard went on being revised until February 1982 ^[1].

Hundreds of parts swapped for a rubber mat: that is how the Spectrum got cheap.

The reason was cost. A conventional keyboard had hundreds of components; Dickinson's came down to "maybe four or five moving parts" ^[4]. The 40 keys are a single rubber mat moulded in one go, with the raised keys poking through rectangular openings in the lid ^[2]. Underneath is a membrane with tracks, and the computer reads it as 8 half-rows of 5 keys: each key pressed sets a bit to 0 ^[5].

The rubber was not the weak point. What failed was the membrane underneath, which over the years became brittle, cracked and stopped making contact ^[2]. It is still one of the most common repairs on a Spectrum 48K, and new membranes are made to replace them.

Sinclair eventually gave in. In October 1984 came the Spectrum+, with hard plastic keys, and curiously some of Dickinson's sketches from the time of the first Spectrum already showed the round-key-on-square-base design that would only appear then ^[1]. In July 1982, Dickinson told Sinclair User that the Spectrum was "a step upmarket" from the ZX81, a machine not meant for the same hobbyist audience ^[1].

Rick Dickinson died on 24 April 2018, one day after the Spectrum's 36th anniversary. As well as the Sinclair cases, he designed the Cambridge Z88 and, towards the end of his life, the case of the ZX Spectrum Next ^[4].