ZX Printer
The Sinclair ZX Printer is a spark printer which was produced by Sinclair Research for its ZX81 home computer. It was announced alongside the ZX81 in early 1981, and available later that year with a recommended retail price of £49.95.
The ZX Printer used special wide black paper which was supplied coated with a thin layer of aluminium. To mark the paper, one of the printer's two styluses passed a current through a small area of the aluminium layer, causing the aluminium to evaporate and reveal the black under-surface. The printer's horizontal resolution was the same as the ZX81's video display, i.e. 256 dots or 32 characters.
The ZX Printer was never intended for word processing purposes, instead being aimed at users who wanted to obtain program listings for reference purposes.
The ZX Printer was also compatible with the earlier ZX80 computer and the later ZX Spectrum, and plugged directly into the expansion bus connector via a short cable. The expansion bus was duplicated on the outside of the printer's connector, allowing other peripherals to be connected concurrently. The printer drew its power directly from the expansion bus, and was sold with a larger power supply for the ZX81 to accommodate the additional power drain. The Spectrum's user manual noted that this was not needed for the Spectrum as its default 1.1A power supply was sufficient.
The peripheral was affectionately referred to during the 1980s by users in the UK home computing community as 'The Astronaut's Bog Roll' . The printer itself also bore more than a passing resemblance to a 1980s-era toilet-roll dispenser, in terms of its visual design.
After around three years on the market, Sinclair announced the discontinuation of the ZX Printer in mid-1984, citing
the fact that by then they were "selling only thousands and sales have fallen", and stating elsewhere that they had no plans to launch a replacement.