In the future, all television sets will be interactive. Or so said the experts who gathered in Edinburgh last week.
The future of television was unveiled to an international audience in Edinburgh last week, when 250 delegates at the iTV96 conference and exhibition saw presentations from leading players from around the world. Two messages came across loud and clear: first, there is no consensus on what "interactive TV" is, as was demonstrated by the diversity of systems under discussion and on display. Second, the Internet dominates all debate on the subject.

So what might interactive TV be? Derek Nicoll, principal organiser of iTV96, defined it as "any form of interaction with the television set in a technological or cognitive sense". Equipment such as games machines, video recorders and satellite or cable decoder boxes all fit the definition, to a certain extent. Interactive TV usually features a special "set-top box", however, which gives access to such services as video-on-demand, online shopping, banking, games and Internet access.

"Interactivity is the key to the education process," said Jonathon Drori, a BBC executive producer who previewed the Corporation's plans for the new wide-screen digital format to be introduced early in 1998. Mr Drori demonstrated an experimental interactive service where viewers with a set-top box and controller could interact with programmes.

The demonstration film showed Diana Moran "helping" Howard Stableford of Tomorrow's World to become fitter. During the film, interactive sequences allowed the viewer to carry out a body mass index check, after which further health information could be selected, as well as personalised information on local fitness clubs. By using a PC instead of a TV, the interactive information could be stored, and links made to the Internet.

Donald Emslie, commercial director of Scottish Television, the ITV franchise- holder for central Scotland, announced the start next month of an interactive teletext-based service. "This is not a trial but a launch," stressed Mr Emslie, in introducing OKTV. "It's here today."

As the system uses the same technology as sub-titles, there is nothing to install. The user needs only a pounds 20 handset from a retailer such as Dixon's. Mr Emslie demonstrated the system by showing how a competition to win a Vauxhall Nova could have been superimposed on a World Cup match. Viewers will be able to send in their Football Pools coupons via OKTV in conjunction with Littlewoods, register their opinions, play games and win prizes. "Points can be built up during the evening," said Mr Emslie, "with prizes at 10.30pm to avoid the 10pm switch to Channel 4's American sitcoms."

Two Way TV is another non-digital system aimed squarely at those who like quiz and games shows. The system lets the viewer join in with shows like Mastermind or Play Your Cards Right, or even have a "flutter" on the horses. This requires a modem connected to a telephone socket to send information back to Two Way TV.

The system launches next March in Birmingham, where it is currently on trial by 750 households. A national launch will follow in autumn 1997. A set-top box, modem and two handsets will cost pounds 99.99 in major retail stores, with a monthly subscription to the service of pounds 95.

ITE of Denmark have taken a completely different approach. Their Interactive Multimedia For You (IM4U), downloadable from the Web, uses a sound signal from the TV to start games on a PC, tailor advertising, feed back to the television from tailored offers or direct the viewer to Internet sites, according to their profile. The system will be tested in Germany and Scandinavia during the coming winter.

BSkyB was conspicuous by its absence from the distinguished company in Edinburgh, and rumours were flying that its delegates had all been pulled out. Ben Adradi, an associate partner with Andersen Consulting, warned that set-top boxes were extremely expensive and that if BSkyB gave them away, "then it's curtains for any other digital service".

Acorn Risc Technologies' prototype NewsPAD attracted a considerable amount of favourable comment from, among others, Bob Glass of SunSoft. The A4- sized touch panel has no controls other than an on/off switch and forms part of a personalised multimedia newspaper project which Acorn will be trialling with a Catalan-language newspaper.

The NewsPAD will be "filled" with broadcast electronic news, filtered according to preferences previously expressed by the reader. The device also includes a loudspeaker, so that news items can be "read out" on the drive to work, for instance. Although the NewsPAD is intended for carrying around, it is currently rather too heavy, weighing about the same as a notebook computer.

Another exhibit gathering interest was Mixed Emotions, an interactive soap created by Rosa Freitag, a Brazilian living in London. The viewer is asked for advice by the characters in the soap and can influence the storyline. Something to be incorporated in Coronation Street and East Enders, perhaps?