The one hot item on the opening day of the Which Computer? Show yesterday was the pocket MS-DOS computer – the size of a Filofax – designed by Distributed Information Processing Ltd, Guildford, and made by Atari Corp in Japan. The thing has a 40 character by eight line liquid crystal display and costs UKP200 with 128Kb 80C88 CPU, UKP300 with 256Kb and interface to a conventional MS-DOS box. ROM software includes operating system, address book, diary, 1-2-3-compatible spreadsheet, calculator and editor, and it runs on AA size alkaline batteries. Atari, with permanent non-exclusive marketing rights, is hoping to get 500,000 off by the end of the year.