Over the last couple of months we've had your home micros performing some fairly weird and wonderful tasks — controlling synthesizers, sampling sounds and playing them back, storing vast quantities of notes and so on. What we're forgetting is that the micro manufacturers in their wisdom have already made some provision for music on most machines, and although it may be as exciting as a damp sponge in some cases, other micros can be little musical virtuosi.

The most obvious examples are the BBC Micro and the Commodore 64. The poor old Sinclair Spectrum only has one sound function, which is very descriptively called BEEP and does little else. You can get sound effects such as zaps and bonks for Space Invaders games out of it, but trying to produce music on the Spectrum is about as rewarding as banging your head against a fish. The new MSX range of computers are a possibility, but there's little music-oriented backup for them at the moment (although JVC promise a MIDI interface with their MIDI home keyboard in mind) so you'd have to do all the programming yourself. More expensive micros such as the Apple, IBM and Macintosh have some possibilities, the Macintosh being quite powerful musically, but if we concentrate on the Commodore and BBC we'll find life much more interesting.

Why is this, I hear you ask? (but only in the same sense that TV presenters keep their promise to "see you again next week"). This is because there are lots of musical aids about for the Commodore and Beeb, including some genuine, full-sized, honest-to-goodness musical keyboards. Ears prick up, stand to attention, chin in, chest out. Carry on.

The current models for the Commodore 64 are the Commodore Music Maker, Autographies Microsound 64, the LVL Echo 1, the SIEL CMK 49, the SCI Music Mate, the MusiCalc Colortone and the Melodion. For the BBC there's a version of the LVL Echo 1, the Acorn 500, the Clef PDSG system and possibly a forthcoming SIEL model.

FROM THE TOP

Let's look at these one at a time, Commodore models first. The Music Maker is an exceedingly inexpensive way of getting some kind of musical control over the computer's powerful, three-voice sound chip SID (Sound Interface Device). It's a plastic moulding with two octaves of hinged keys which sit over the top two rows of the computer's typewriter keys — it's surprisingly playable! There are lots of software packages available for the Music Maker, from music games to educational packages to synthesizers and sequencers. You have a simple synthesizer graphic layout on the basic package with waveform selection, octave and so on, with some preset sounds and a user-definable option. There's also a Casio VL-Tone style facility for simple backing rhythms over which you can enter a tune and then time-correct it by tapping a single key. The basic package is around £29.95 and it's available in many computer departments.

If you want a full-sized real keyboard, your cheapest option is the LVL Echo. It's a three-octave model which comes complete with a software package on disk; the adapter cable plugs into the 64's cartridge port and sound emerges from the TV speaker. The software offers you preset sounds representing conventional instruments, a few oddities and a special effects section for nonmusical noises, with a simple synthesis section for programming and saving sounds but no facility for composing and saving tunes.

SIEL's CMK 49 is a new product offering a four-octave keyboard as the first part of an expanding system. Again it attaches to the 64's cartridge port, but it also has a follow-on connector which allows you to attach a SIEL or other MIDI interface. This lets the keyboard act as a MIDI master control ler with a programmable split point.

The software consists of an extensive selection of monophonic and polyphonic sounds, some of which are very impressive. The Edit page allows you to modify these sounds and store them for later use, or to create new sounds. Unfortunately you can't get at some of the 64's wackier sound facilities, which is a pity since the possibilities of independent envelopes and combined filter modes are quite extensive. Again there's no compositional software yet, but at £129 with the promise of many more accessories to come, the CMK could turn out to be a bargain.

The Autographies system has been a long time a-comin', and it's still under development, but it's much more ambitious than many others since the software includes full compositional facilities and the hardware incorporates MIDI interfacing and the option of a sound sampling unit. The basic four-octave keyboard at £129 connects to the 64's joystick ports and features two sliders which can be used as live performance controllers for modulation or filter changes.

The synthesis software allows control of all the 64's sound parameters and there are also extensive sequence, looping and multitracking facilities within the limitations of the three voices available. The £229 digital sampler, which is expected to produce a 1.8s monophonic sample, allows replay from the keyboard at any pitch, or from the sequencing software. Unfortunately this bit's still under development at the time of writing!

Touch Sensitive

The Colortone is a touch-operated rather than a mechanical two-octave keyboard from Waveform in the States — it's fully compatible with the powerful Musicalc software range, which includes hundreds of options in pre-programmed backings, preset sounds, scales, score printing and compositional techniques, but it's unlikely that the keyboard will appear in the UK for economic reasons. MusiCalc UK may well develop their own version though.

The Melodion is a bit of an unknown quantity, but there seem to be no plans to import it into the UK at the moment in any case. For an extensive list of Commodore accessories with contact addresses, you could do worse than to consult Electronic Music On The Commodore 64 by Mark Jenkins and Commodore 64 Music by Ian Waugh, Sunshine Publications, price £6.95 from your local WH Smiths and other booksellers of good repute.

Onto the Beeb, and the best bet here is the appropriate version of the LVL Echo 1 detailed above. Some of the sounds produced as presets are a little weak, but the provision of an optional miniature combo amplifier which overrides the BBC's built-in speaker (the EchoSound at £50) is a great advantage. The Beeb, like the Commodore, can be played three-note polyphonically with lots of envelope and filtering options.

SIEL are fast converting their software to the BBC, so don't be surprised to see a keyboard from them to run a version of the CMK49 software. Island Logic's excellent 'Music System' software on tape or disk, shortly to be available for the 64 as well as the Beeb, may well have a keyboard option in the near future, and possibly a MIDI interface too.

Also to be taken into account is the Acorn 500 synthesizer, a hardware/software synthesis and composition package for around £199. The disc drive-sized voice module is 16-note polyphonic and is supported by a special music composition language. Sounds are defined by additive synthesis which seems complex at first — and still seems complex when you've struggled halfway through the massive handbook.

Still, the sound potential is there, and the Acorn provides an escape from the limitations of the number and quality of voices on the computer itself. The point we're struggling towards slowly is that a full-sized keyboard add-on is a possibility for the not-too-distant future, but of course having paid £199 for the voice module, the economy of the 'play your computer as a synth' idea is already lost.

If you're into building kits, Clef have their PDSG (Programmable Digital Sound Generator) which is a 32-voice machine controlled by the BBC Micro. Again, the quality of the voices is much greater than anything you'd find on board a computer and you do have a real keyboard to play, but the cost is quite considerable.

In the near future there's going to be a spate of home micros with particularly powerful built-in sound chips. The Atari 310 ST features a MIDI interface as standard, and another of the planned Atari machines has a 16-note polyphonic sound chip with 64 harmonics per voice and a wide range of envelope and other control parameters. You'll have to hold your breath for anything up to 12 months for these though.

Before you dash out to buy a keyboard for your existing micro, it's as well to have some idea of the limitations. Playing from a real keyboard only overcomes a few of the performance problems of sound chips which are basically designed for effects rather than for music, and you're not going to get screaming lead lines or huge lush string chords out of any unexpanded home micro. Nor are you going to become a star of stage and screen, because taking any home computer (with or without keyboard) onto a stage with musical intent is about as utterly reliable as the rhythm method.

However, don't be discouraged by the limitations — be encouraged by the fact that, for lots of applications in composing and rehearsing and producing sound effects, your home micro and a cheapish add-on keyboard may save you most of the money you were about to spend on that shiny new synthesizer.