The Jupiter Ace was a British home computer of the 1980s, marketed by a company named Jupiter Cantab. The company was formed by Richard Altwasser and Stephen Vickers, who had been on the design team for the Sinclair ZX Spectrum. The machine somewhat resembled a ZX81 in a white case, with rubber keys like the spectrum, It displayed output on a television, and programs could be saved and loaded on cassette, as was standard at that time. The machine came with 3K of RAM, expandable to 49K.
The major difference from the ZX81, however, was that its designers intended it to be a machine for programmers: the machine came with Forth as its default programming language. Though this gave a great speed advantage over the interpreted BASIC that was used on other machines, it kept the Ace in a niche market. Sales of the machine were never very large; surviving machines are now (October 2001) quite uncommon, and fetch quite high prices as collectors items.