Grid Computer Systems’ UK subsidiary has taken exception to a Compaq Computer Corp advert that states you can’t run a gas plasma screen off batteries: Grid says that the ad is misleading as for two years it has had a portable, the GridCase, that is battery powered and has a high resolution gas plasma screen; the company suggests that Compaq should stop calling its Portable I, II and III ‘portables’ since to call a mains powered computer ‘portable’ is cheating the market and also that its rival should be referred to the Advertising Standards Authority; for its part, Compaq says that Grid has taken the advert quote out of context and that, for most people, battery power is less of a necessity than extra performance.