IF YOU spent last weekend relaxing in front of the box, make the most of it - for the days of the couch potato may be numbered.

The era of interactive television is fast approaching and if you look at all the technologies due to be launched in the next few years, there are many people who will hanker after the good old days of the soap opera and feature film. Probably the most dramatic change in the way we use television will come with the advent of video on demand (VOD) services.

Imagine this: You come home after a hard day's work. You don't fancy Terminator 17 on ITV; BBC 1 is showing Return to Eldorado and BBC 2 and Channel 4 closed down years ago in cost-cutting measures. Your cable channels offer nothing special. You pick up your remote control and the VOD system taps in to a local computer and up on the screen pops a menu of options. You can choose sports, feature films, foreign language films, documentaries and other topics. You select documentaries and, by a couple of quick choices, pick one on Chilean Nose Flute playing.

To a certain extent this exists already, using cable TV technology. But within a couple of years the system I described above should be available over ordinary telephone lines to 90 per cent of British homes.

This technology has cable TV companies around the world very nervous. In Britain, British Telecom would be prohibited from offering VOD itself because of various regulations, but there is a chance that other companies (including cable companies) might be allowed to use BT's lines to deliver programming. While the technology is mainly seen in terms of VOD, there are other multimedia opportunities such as computer games and home shopping that would be possible. The regulatory situation for these is much more complicated. In the US, however, these types of interactive services are set to take off with a system called TV Answer.

TV Answer uses radio signals in a system similar to cellular telephony, to communicate with a set-top box. This controls the TV, the video and cable system.

At its simplest, it can be used to send messages from the user to the studio so, for example, viewers can vote on what they want to see next on a football show - an interview with the quarterback or a replay of the last touchdown. They can also take part: predicting where the next pass will go, for example, with the viewer making the best number of correct choices being awarded a prize at the end of the game.

TV Answer can also be used for home shopping and home banking. All your details, name, address, credit card number, are stored in the machine. Some adverts will have TV Answer data attached and you will be able to press a button to be sent a brochure, get a salesman to phone you or simply to buy, buy, buy. There are plenty of dangers with this type of system but the basic technology offers some fascinating opportunities.

All this is not just happening in the United States, however. Interactive TV is already in operation here. The Canadian cable company, Videotron, with franchises in London and southern England, has a system called Videoway which allows viewers to select camera angles in a football game, watch action replays, choose specific band members while watching a pop concert and, using the same interactivity, take part in computer games. So far the company only has a limited number of programmes for the UK market but in February it screened its first Videoway English football game.

But if you do not have a Videotron cable system in your street, your TV can still be interactive even if it is not connected to the outside world. Available for almost a year, Philips' CD-I machine is, essentially, a device for creating interactive television and some of the video games machines about to hit the shops are similar.

The CD-I player plugs into the back of the television and, by using a remote control, you decide what is read off the CD-I disc. This can involve games, such as armchair golf or battleships, or guitar lessons, with you deciding what your teacher on the screen will show you next.

By the end of this year, CD-I will have the ability to play video clips. This will make interaction all the more fun. For example, there will be interactive movies where, in a murder mystery, you can decide where the hero detective goes next - into the house, into town or back to bed.

Philips will not have this all their own way. There are several other companies with products similar to CD-I under development and the games makers Sega and Nintendo are putting their weight behind their own technology. Sega is about to launch its CD player, which will allow you to play games that are essentially interactive TV.

The best example I have seen is called Night Trap, where you have to stop killer zombies dragging teenage girls into their nether world. Not exactly politically correct, but completely new as far as computer and video games are concerned. When you decide to jump from room to room you see a video clip of what is going on in that room - a zombie disappearing out of the room, the girls dancing, or whatever. It really does feel as if you are dashing from room to room trying to save these skimpily dressed, dizzy creatures (- I did say it was not PC).

Interactive TV looks set to be with us in a big way before the end of this century. It will allow us more control over what we watch, how we watch it and how we interact with the world around us.

But one thing it is not likely to do is stop couch potatoes being couch potatoes. Interactive TV will just mean that finding undemanding, mindless rubbish will be even easier. Sounds like heaven, doesn't it?

(Photograph omitted)