Back in the May issue of One Two we ran the first Preview of Yamaha's CX5 computer after a special demo set up by FM synthesis expert Dave Bristow. Stage two has now arrived, as we've had a chance to play with one at home for a while. We were, however, without important English instructions — the only help came from some brief notes and a couple of Japanese manuals. So let's see how we got on.

Connecting up is easy: there's a separate power supply to fire the main CX5M computer (as it's now officially designated in the UK). It also comes with a YK01 44-note F-C music keyboard, which has a computer-connector plug. Your own cassette machine will connect via the supplied DIN-to-three-mini-jack lead (red/mic, white/phones, black/remote — a machine with a remote option is obviously good as the computer can switch the tape machine on and off itself). A co-ax lead connects the computer to monitor or TV — I plugged straight into my colour TV and after a bit of fiddling around channel 40 got a good clear picture off the computer.

Yamaha intend to supply the computer complete with a YRM12 Voicing Program ROM cartridge — we suggested this in our Preview, but Yamaha have also put another £40 on the retail price to cover it. You don't get something for nothing, it seems.

So we'll assume this is the package you're faced with, and switch on with the Voicing Program inserted in the slot at the top right of the computer. If you wanted to do other computerish things with the CX5M you'd leave the cartridge out and have a normal computer page come up with a cursor standing ready.

Anyway, Voicing Prog in, switch on, and up comes an impressive looking list called the Command Menu. Fascinating use of language, these computer chaps have.

First on the menu is Directory: type in DI and up it comes, listing all the 48 internal voices. No matter how much you fiddle around with and poke at the voices with the software, these same voices will always be available when you switch on. The last two spaces of the presets are virtually blank — well, 47 is called "CSM" whatever that may be, and makes no noise; 48 is noiseless too. These are good places to start building your own sounds, though you can take the other method of subtly modifying or completely changing the preset voices, using their inherent "knowledge" of FM to point the way to what you feel are more interesting rackets.

Certainly if you're going to get anything creatively interesting and provoking out of the 5, you'll want to make your own voices, so it's comforting that Yamaha have decided to include this Program as part of the package. It makes the computer into a very impressive programmable FM synth.

There are two main routes to take: the first is to use the existing voices and/or make up new voices to play with as a real-time synth; the other is to create specific voices for use later in the Music Composer program, which lets you write music with FM sounds in up to eight parts.

But with the Voicing Program, let's call up one of the preset voices to see what can be done. So DI for directory, choose one and type in the number, then hit return. Up comes the standard CX method of displaying FM voices: there's the name of the voice, an algorithm diagram to show the shape of the constructed sound, the LFO type and make-up, and various values for each of the four operators (with particular emphasis on the envelope). The four operators combine in different "shapes", and each shape is called an algorithm (of which there are eight on offer here — not as many as on a DX synth, but more than enough to be getting along with).

Tricky, this. If you have a total lack of knowledge of FM synthesis, then all you'll see is a screen full of numbers, letters and little white bar graphs on green blocks. This is actually rather off-putting if you're keen to make new sounds straight away. My first reaction, for example, was to try to listen to one of the operators on its own so I would, I thought, be able to get more of an idea of what they'd do all mixed up. This didn't work, as the operators only wanted to work together. So you have to start playing with combinations of sounds, building up confidence as to which parts of the algorithm do what, but without being able to hear this individually.

The white bars on the green blocks represent the values for the envelope parameters, and for the level of each operator: these and the frequency number, displayed as F1, F2 etc above the operator chart, offer together a good place to start manipulating these sounds as they not only have an obvious visual part to play here, but are crucial to the tone, shape and quality of the resulting sound when thrown in together. In a way, this whole on-screen method of sound construction got me much further with FM more quickly (relatively) than much wrestling with a DX7, where all you get is a little window displaying one piece of the information at a time.

Yamaha's offered sounds themselves show some of the possibilities with FM: your reactions to these preset 48 voices obviously have a good deal to do with your own taste and what sounds you need for your purposes, but, at least you have plenty of facilities to change what's here. My particular favourites from the 48 were: BRASS1 (1), bright and throaty; STRING 1 (4), a lovely bowed cello sound; EPIAN02 (7), Rhodes-ish and tingling; EORGAN2 (13), as Hammondesque as you'll get; VIBRPHN (21), with just the right tremolo vibe; and the well funky CLAV (25). Some of the others I'd be pushed to find a use for; a few of the percussion voices are nice to have, though Yamaha haven't given you an obvious bass drum, so you'd have some constructing to do for drum sounds on the Music Composer.

There is a slight but distinct carrier noise with the sounds, audible as a low-level middle-ish hiss, and more apparent on particular voices (though only really noticeable if you put it through a good system — with it whacked through my Quad amp and Rogers monitors it was there all right). Course, if you just leave the sound going through a tinny TV speaker, you obviously couldn't care less anyway. The hiss is the sort that would get lost in ensemble mixes, but tracked up it could get intrusive.

I made up some voices of my own at this stage — not wholly successfully, I admit, as my FM credentials are still slim, but I'm getting there. You can hang on to a voice you've made up in a Save Buffer, a sort of limbo area before you decide what to do with it. Then you enter the new sound with its name into the directory by assigning a number to it. Eventually, when you've added all the new voices you want you can save this new directory of your voices — you have to save a whole directory's worth, or "file" as you'll need to call it, and can't save individual voices. Cassette-saving of these files you create is easy. The software reverts to the 48 presets, and a file you load into the computer back from your cassette becomes voices 49 to 96. In this way you can always have 96 voices on call, 48 of which could all be of your own design.

Another section you can get to from the master Command Menu is a sort of performance control and peripheral section, which you reach by typing MU for CALL MUSIC — you can also get this and the 48 presets (only) without software cartridges plugged in. Anyway, MU brings up a display of preset BRASS 1 from the factory-set voices. Let's keep looking at this BRASS 1 display as it'll show the general changes we can make to the sounds and what we can bring in at this CALL MUSIC level.

Five boxes are headed Poly, Rhythm, LFO, Mono, and Balance. First things first: you can put a split anywhere on the music keyboard by typing K and hitting a key: fully poly requires one mono note at the top and identical voices for poly and mono sections. A poly/poly split is not available. You can put any of the preset sounds on either side of the poly/mono split, and reverse the assignment by typing "U" or "(U)".

You can change values of all the displayed parameters in the five boxes by using controls on the computer keyboard, so in the Poly box we can sort through the preset voices, or loaded voices, until we get one we need, while the other three lines cover pitch and amplitude modulation, and turn sustain either on or off (no level). The Rhythm box (hah) is an odd inclusion, very home-keyboard, very dull and unprovocative. Good for when you show it off to Auntie Mabel.

Mono gives voice options plus portamento types and rate. The Balance box adjusts such levels as exist from other areas and, most usefully, operates the "sequencer" facility via a few computer function buttons. I chucked in five minutes' worth of unwieldy chords without interruption on perfect playback, though apparently there are 2000 steps on offer. You can also save "sequences" to cassette, but unfortunately there's no evidence at all of any syncing or triggering options, which limits this to being merely a short-space recorder.

Now we take out the Voicing Program and replace it with the other main program on test here, the Music Composer. Yamaha will also be making available a program cartridge each for visual voicing of the DX7 and DX9 (the CX5 has, of course, MIDI sockets.) The company also has something called Macro Musical, which apparently puts FM sounds into your regular computer programs, so you can zap Klingoids with gentle harpsichord tones, for example. But on to the Music Composer, and on we switch. Coo, lovely!

Up come two staves running across the blue screen, and a darker blue strip underneath has all kinds of musical symbols and other signs on it. There's a red cursor down there too (on a crotchet when you turn on), and up on the stave lurks a blue cross-shaped cursor.

You can write eight parts on to these staves in musical notation, one part at a time, and with virtually limitless space. Enough for most pieces of reasonable length, anyway. I certainly never ran out of room. You can choose any of the available voices to play the parts on, eight different ones if you so wish, either from the presets, or any you've made on the Voicing Program and saved to cassette — these have to be loaded into the Composer program as soon as you get the thing going.

So let's have a try at putting some notes down. First we have to turn on the sound and the music keyboard: there are two ways of working on to the screen, one of which tells it to do things like select a part, play a part back, and save compositions to cassette. The other way is for note selecting and generally writing the parts on to the staves.

The three main methods I found of writing in music were: by pressing notes on the keyboard; by moving the blue star cursor to the stave position for the note; or by using computer keyboard buttons to select the pitch. In each case the technique was combined with a selection of note type, or value, from the lower blue strip.

But in the case of the music keyboard entry method, perhaps the most attractive for use by, er, keyboard players, the scheme takes on something of a computer game aspect as the cursor will leap back and forth along the possible notes while the operator must release the music keyboard note as the required note type comes into the firing line.

It is a shame, too, that you can't actually enter pitch and note value from the keyboard, but maybe wanting a perfect real-time keyboard-to-notation converter for around £600 is asking too much.

Something else I wanted to do pretty soon was to write chords, and this involves rather a messy and confusing set of actions where a chord-like symbol is selected from the blue strip. You then tell the computer what you're going to do (poly = 3 for a triad, for example), and then write in the notes via your chosen method all on to one stave. The notes come out thinner than normal so you can see where you've written chords, and the machine does indeed magically play chords when you run it back.

After you've written the parts in you'll need to add expression to get some sort of feel into the music, otherwise it's all a bit stilted and sort of step-time-like. Some expression marks are written as you would in music, like "ff" for fortissimo; others need computer keyboard function buttons, like "<" for crescendo. Although this is necessary to breathe life into the stuff, it is laborious if, like me, you have little written-music knowledge and have to look things up continually. That's true of this whole program, in fact, but I do feel as if the computer is helping my education along.

Once you've written in as many of the eight parts that you need — and you can't see one when writing another — then you can hear them back by typing "play = ". This will play back everything written, all the parts you've made, while "play = 1", for instance, would just play part 1, and so on. It isn't possible to play a couple of selected parts together from an eight-part composition, although you can tell the computer to play one part straight after another. And, mais naturellement mes braves, you can save your compositions on to cassette for reloading later, as you're faced with the dismal prospect of all your work disappearing when you turn the machine off. As can happen if you press the load button and the return, but that's my problem (he sobbed).

At the moment I'd sum as:
Likes Visual introduction to FM and (for me) music notation; compact package with so many facilities; endless store and save to cassette; keyboard feel (music and computer); imminent English instructions.

Dislikes No display of voices for Music Composer; carrier noise on good quality systems; sudden change of computer keyboard functions in different modes so you don't get the symbol you type; only stereo audio out, not eight parts on music Composer; feeling the desire to learn Japanese.

We'll keep you posted on developments, both in the light of English instructions, and when other software becomes available, from, Yamaha and other sources. In the meantime, thanks to Kuma Computers whose childish and violent game "Bomber Man" actually felt calming and amusing after hours of CXing. I still can't get over 5000 points, however. Maybe I'm just clumsy with computers.

Yamaha CX5: £599