TALK ABOUT hard to keep up to date, mate. It doesn't seem more than a couple of months ago that we first reviewed the Syntron Digidrum, a neat little add-on for the Commodore 64 computer which turns it into an all-singing, all-dancing digital drum machine. In fact it was in the August issue, and here we are looking at a set of updates which make its earlier capabilities about as convincing as a C&A shirt in an episode of Miami Vice.

First, then, a quick update on the aspects of the Digidrum which haven't changed. It's still a small black plastic box intended to fit into the Commodore 64's Cartridge Port, and it still has an unconfusing two sockets — Audio Out (a standard jack) and Trigger Out (a standard phono). The underside of the cartridge is labelled so that you can't insert it upside down (producing backwards drum sounds perhaps?).

As before, the module only comes to life when the accompanying software is loaded into the computer. At this point we come to a problem, because you may not have a Commodore 64. An electronic typewriter, digital watch or micro-chip controlled toaster simply will not do.

Once you've loaded the software the Digidrum displays a menu, then a compositional chart, on the screen. This is where the improvements start to come in, because while the old display was useable enough, the new one has been much tidied up. It's now possible to hear the individual drum sounds by tapping a single key rather than having to program and run a pattern; the basic sounds are crash cymbal (C), open hi-hat (0), closed hi-hat (H), "drum" (small tom) (D), snare drum (s), grand tom (!) (G), floor tom (F), and bass drum (B).

These sounds are about on a par with those on Korg's inexpensive DDM 110/220 PCM drum machines. The sampling quality is outstanding for the money, and although some of the sounds (particularly the cymbals) are clipped a little short they're still useable. You can compose a pattern simply by entering beats on the compositional grid and play the pattern back by pressing the computer's Function 7 key. The Function 1 key determines the end point of the pattern and so can allow you to program patterns with any number of beats.

It's now possible to erase individual instrument sounds rather than having to erase all the instruments on one beat; you can have up to three sounds playing simultaneously on any one beat, and the cursor will now optionally scroll to the next beat automatically.

It's possible to write up to 51 patterns (rather than the previous 10), which are stored in the computer's memory as soon as you assign them a number at the top of the screen. Once you've written your patterns (or chosen some of the demo patterns that take your fancy) you can go to the Track Composition Page, which again is tidied up and which allows you to program songs of 100 steps.

One song step consists of two numbers: the number of the pattern you want to hear, and the number of times it's repeated. You can start composing a Song with a selection of 10 patterns, but you can also load more as you're composing — so the number of patterns which can be included in a song is limitless. The computer will hold 10 Songs at the same time as its 51 rhythm patterns, and will load a new set in about 10 seconds — "fast enough to change sounds in an on-stage environment", claim an optimistic Syntron who obviously have unusually reliable power supplies on their Commodore 64s.

How difficult is it to program a song? Well, all you have to do is type P1, 4R, P2, 3R, P3, 1R and you'll have a neat bar with two patterns and a variation. The Rs just stand for Return, the Ps for Pattern, and the numbers after the comma for the number of repeats of that pattern.

The Song-mode programming is massively improved over the original version by the addition of facilities to copy whole sections (say to repeat a chorus later in a song), to delete and insert any number of steps, to erase whole songs and to list the content of songs. You can set the tempo from 1 to 64, with ranges from 33-50 being most used, although there's no facility to have patterns of different speeds within a song.

Being software-based, the Syntron obviously loads new information from disc (or cassette if you really want to feel your life passing by), and the Commodore's disc system is pretty slow compared to the BBC's, for instance. But you can load a new set of 51 patterns and 10 songs in about 30 seconds, and you can give a name of up to 14 letters to a new set and save them to disc in about the same time.

The third disc mode on the Syntron is Load Sounds, which allows you to increase the sonic capability of the kit as a whole. New sounds must go over the existing sounds and come in sets of four so for instance 1/Glass and 2/Glass indicate two sets of four glass instruments, and C/Conga indicates a conga sound which will replace the built-in Crash sound. You can change the prefixes used in order to create your own kit from any combination of sounds in any positions.

The final option is a Quick Loader which loads the software (without sounds or patterns) in about a tenth of the normal two minutes, assuming you want to use your own rhythms rather than the demo rhythms and your own kits of sounds rather than the standard kit. For synchronisation purposes the Trigger Out from the phono socket is one positive pulse per beat — which is fine for analogue synths and sequencers, the EDP Spider and most arpeggiators, but not much good for MIDI or Sync 24-based equipment.

Overall the Digidrum is pretty easy to use, and by this time you'll be wondering what the final effect's like. The answer is bleedin' amazing — instant Depeche Mode as soon as you load the Glass Instruments file, instant Simmons Kit as soon as you load the Electronic Percussion file, an excellent Latin set, lots of effects such as lasers and Rattlesnake, some horrible bendy toms which shouldn't have survived from the original version, and much more.

Agreed, the Syntron can't sample, but you won't find many of its sounds on any other drum machine so your chances of sounding original are fairly high. It has two main problems — no separate outputs (and before you ask, not a chance in hell of adding them) and no sound feed to the monitor, so you will always need an amp or a rather specialised kind of TV with an audio input to do your composition.

The remaining question is whether the Syntron has any appeal to non-computer owners, considering the fact that you can get a Commodore 64 and disc drive for about £180 nowadays. Let's put it this way — if you could use a digital drum machine and you're already thinking of buying a computer, the 64 is by far the best bet for musical purposes and it's cheaper than the BBC. There's nothing like the Syntron available on any other micro, so the thing's a damn good argument for buying the computer on its own. If you already have a Commodore 64 you shouldn't be reading this — you should be filling in your order form.

SYNTRON digidrum module: £65

CONTACT: Syntronics, (Contact Details).