Computers: Keying in to the digital music revolution: How to read the score on buying equipment

Apple Macintosh owners already have sound processing built into their machines, so all that is required is a Midi interface, which you can find for about pounds 50 through any good Mac dealer. Owners of PC-compatible systems need both a Midi interface and a sound card, writes David Hewson.

Everyone needs 'sequencer' software, which lets you record and mix together different Midi tracks and may also turn what you play into instant musical notation. The best bet for a sound card currently is the Gravis Ultrasound which, with a Midi interface, will cost you about pounds 190, including VAT, and comes with a wide array of sound and music software, including a worthwhile sequencer.

Other cards may sound good, but usually include free games software so you may have to spend another pounds 100 on a sequencer.

An alternative route, for Macs and PCs, is Yamaha's 399 Hello Music package, including sequencing software and an external box containing sampled sounds and a Midi interface. The sound quality is excellent, as one would expect from Yamaha, but the documentation could be better. But it saves the PC user buying a sound card. On the other hand, they will have to live without sound for non-musical PC applications.

A halfway house is the Miracle Piano System, for both Mac and PC, at about pounds 299. This is an abbreviated piano-like keyboard with software and a cable to connect to the computer. The Miracle is designed to teach basic piano playing skills through an interactive course, including musical games, and is excellent. The software includes a basic sequencer that can export Midi files and, if you buy a full-blown Midi interface, you can use the Miracle keyboard to drive it just like any other Midi instrument. This is an inexpensive way to play with music on the computer before you make a big financial commitment.

Virtually all the cheap keyboard muzak machines you see in the high street include Midi interfaces, but most of these are gimmicky toys with poor sound and keyboards. The more expensive electronic keyboards are best left to the experts. If you want a home piano that will speak Midi, too, you need a digital instrument.

Yamaha-Kemble is the leader in this field with its Clavinova range. Other manufacturers include Akai and Roland. Digital pianos fall into two families, those that have the bells and whistles of electronic keyboards, such as built-in rhythms and a wide range of sounds, and those designed to be good home pianos, normally with a few piano voices, as well as harpsichord, organ and vibes.

Digital pianos start at about pounds 1,000, but you would do best to save until you can afford twice that price if you want something that is a substitute for a real piano, like Yamaha's CLP 123 ( pounds 1,999).

A cheaper option is Akai's offering at pounds 1,299, which was fine except for the mid-range where, for an experienced player, the piano sound became distinctly thin, though, to be fair, children loved it. But play a digital piano before you buy it and pay particular attention to the middle registers.