Having mice always causes problems - ask anyone who's got one. The switches pack up and the small rubber ball picks up dust and dirt and happily deposits it around the internal rollers making the movement as smooth as treacle. No matter how often you take it apart and clean it, the problem re-occurs. It's an unavoidable fact of life.

Or is it? There are mice without balls - and Alfa Data are one of the companies that have developed one. The two rollers which are normally used to translate mouse movement into cursor motion on the screen have been replaced by a couple of LEDs which are situated underneath the mouse. The light beam from these is reflected off the special mat, included with the mouse, and picked up by a sensor. Obviously, less moving parts are used, so there is less to wear out.

The mouse mat is a sturdy, plastic-backed affair which should stand up to extensive use. With a resolution of 300 dots per inch, the Optical Mouse causes the cursor to speed back and forth across the screen and as long as good contact is made with the mat, the movement is very smooth. The other advantage of not using a ball-operated mechanism is that it is practically impossible to make it 'skate' - a problem that often occurs when you move a conventional mouse very quickly and the cursor on-screen doesn't keep up.

The switches are of the high-quality micro-switch type and produce a very positive 'click' when pressed. They should last for years - the manufacturers rate them at one million operations. The overall design of the mouse ensures it fits very nicely into your hand with none of the squat, box-like feel of most mice. And with six feet of cable, you can happily position it wherever you wish.

The Alfa Data mouse may be used with either the Atari ST or the Commodore Amiga - a switch on the base selects between the two - and the package also includes a mouse holder which can be fixed to the side of your monitor. The price is about double the cost of a standard mouse, but remember, the longevity of the Optical Mouse is likely to be measured in years. The manufacturers certainly seem to believe so; they provide a two year warranty. Go on, treat yourself!