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Yamaha CX5M

Music Computer and Software

1984's most eagerly-awaited electronic music product is finally making its way into dealers' showrooms. David Ellis has been taking a look at the micro itself, Yamaha's exclusive FM sound chip, the controlling keyboard and the first batch of software.

Take a standard MSX micro, give it an FM chip, a MIDI controlling keyboard, and some music software, and you've got this year's most eagerly-anticipated electronic music product. It's almost ridiculously good. David Ellis

With so much ballyhoo about the hitherto intangible CX5M in the past six months, it's been a mite difficult to separate fact from fiction. And it has to be said that leaning over the shoulder of Dave Bristow, Yamaha's principal CX5M demonstrator, is hardly the same as honest-to-goodness hands-on experience. In fact, the situation as regards reviews of the machine has been greatly complicated by the fact that Microsoft, the American company behind MSX BASIC, have been allowing computer magazines to review a Yamaha micro called the YIS503, which to all intents and purposes is the same as the CX5M but without all the software goodies that transform a fairly standard micro into something rather special. Indeed, as Yamaha-Kemble have repeatedly and patiently pointed out to telephone enquirers, this was a machine aimed at the Japanese home market, not the UK micro arena. So, all in all, it wasn't particularly sensible of Microsoft to release it for review.

And, of course, the problem with this premature exposure created was a flood of interest in a product that didn't actually exist on the UK market, and therefore succeeded in causing a great deal of frustration to one and all - including Yamaha-Kemble. As Martin Tennant of said company put it, 'If I'd had a quarter per cent share in every CX5M that people wanted to buy when it wasn't available, I'd be holidaying in the Bahamas now!' So, if you'd wondered why E&MM hadn't reviewed the YIS503, or even given space to an over-the-shoulders-of-Bristow account of the CX5M, there's the answer.

In contrast, the CX5M is Yamaha's official MSX micro for the UK market. But as most readers will already have gleaned, it's also a great deal more than just a standard MSX micro. In fact, its musical capabilities are such that its clonal parentage is little more than of passing interest. First, though, some background to fill in the whys and wherefores of Yamaha's MSX endeavours.


As anyone who's been following the progress of micros through the late seventies and early eighties will know, the one thing that can be relied upon is diversification from anything like a common standard. Whether that's such a bad thing in a rapidly expanding field is a moot point. To be honest, I'm inclined to side with Sir Clive Sinclair in his opinion that MSX freezes technology and software at a stage when it would be more profitable to look ahead. To make matters worse, the MSX standard laid down the law on a particularly uninspiring sound chip - the AY-3-8910 - which didn't exactly augur well for the musical side of MSX. But be that as it may, this was the fait accompli that Yamaha were faced with.

So, how does a manufacturer of high class synths, pianos, harps and even motorbikes produce an MSX micro without getting egg on its face in the sound department? Well, quite simply, by combining their expertise in FM synthesis and the design of custom chips. So, just as the DX7 polysynth saw the use of custom operator and envelope-generation chips churning out 12-bit data for our delight and edification, so Yamaha's new MSX micro gained precisely the same sort of squashing of FM principles onto rather less than a handful of chips.

In fact, Yamaha approached the problem in two stages: first, they designed their own version of the AY-3-8910 for use within the basic machine (a necessary evil to ensure compatibility with other MSX software); and second, they parcelled up a custom FM LSI with a keyboard interface and MIDI in a special add-on called the SFG01, which was available separately for their MSX micro along with a choice of mini or full-size (macro?) music keyboards and a range of software.

Over in the land of the Rising Yen, Yamaha released this MSX micro in two different guises: the YIS503 (32K RAM) and YIS303 (16K RAM). Like other MSX micros, the YIS503 was priced at around the £200 mark, whilst the SFG01 FM sound module and MK01 mini keyboard were available together for a further £100.

Now, all this happened more than a year ago in Japan. The UK situation is, of course, rather different. First, it's the CX5M, not the YIS503, that's coming onto the market shortly. Second, it's being marketed only as a £599 package consisting of the CX5M, SFG01, MK01 and YRM12 FM voicing software cartridge. It's hard not to notice that rather steep price increase, but as Martin Tennant pointed out to me, air freight is expensive, service facilities have to be provided, and on the other side of the value for money coin, a CX5M purchaser is actually getting considerably more than a DX9's capabilities for rather less outlay.

SFG01 Module

The crux of the CX5M is the SFG01. Without this FM sound module, the CX5M would be yet another MSX micro without the 'M' for music. In fact, the SFG01 is the sort of add-on that just about everyone working in the micro music industry has been itching to get their hands on. The actual module measures about five inches square and slots into a recess on the underside of the CX5M, where it's bolted into place. Opening the module up reveals plenty of metal screening to avoid radio interference from the FM chips, and a well-constructed, double-sided PCB holding about 12 chips and various bits and bobs.

The important ones to note are those with the Yamaha code 'YM-'. Locked inside just one of those large chips (YM2151) is the secret to the DX sound. From the come data lines et al to a dual DAC (YM3012), and hence to op-amps and the output. Just two chips doing all that - makes you think, doesn't it? Alongside, a couple of other chips look as if they're having something to do with MIDI communications (YM2210) and keyboard scanning (YM2148), while at the side are a bevy of sockets - namely MIDI In and Out, the keyboard connector, and left and right audio outputs.

On the FM synthesis side, the SFG01 has 32 Operators available at your beck and call. Eight-note polyphony is the norm, so these Operators get assigned four-a-time to each voice. Then, like the DX9 (which also uses four Operators/note FM synthesis), these Operators can be arranged in eight different patterns - what Yamaha somewhat confusingly term 'algorithms'. However, where the SFG01's capabilities zoom ahead of both the DX7 and DX9 is in the delicious fact that eight different algorithms/instruments can be played at once. So, if you want to multitrack different parts with different instruments, it's no problem. In addition, rather than limiting the output of the SFG01 to just the monophonic output of the DX range, Yamaha have sensibly seen fit to endow the module with stereo outputs. More than that, each of the eight voices can be altered between output left, right and centre.

And the sound quality? Well, like its DX brethren, the SFG01 is whisper-quiet when nothing's sounding. More to the point, the sounds themselves have a breathtaking clarity to them. If there's any criticism to be made, it's when sounds are output at the low end of the spectrum, because here, in common with the DX7/9, some carrier noise does tend to creep through. Interestingly, when this appeared with the CX5M, it was most obvious on instruments using algorithm 3 (brass, strings, and pianos mainly), and manifested itself as a sort of added whistle whenever notes of an Fm7 chord were played below middle C. A bit like a certain frequency making something in the body of an instrument and its resonant pennyworth, really. Now, you could argue that this adds to the organic appeal of FM, ie. simulating even the behaviour of resonating bits of wood and metal, but personally I found it a mild annoyance. Still, one way around it may be to take greater care in the initial construction of sounds. Just remember that most things are both achievable and avoidable with FM synthesis!


Of course, without software the SFG01's as dead as a dodo, and the proof of Yamaha's musical pudding ultimately rests on what they're providing to goad all those FM parameters into action.

First, though, a word about the MSX attitude to software. Well, total compatibility and fast-loading are the two main requirements. The software side of MSX (it stands for Microsoft extended BASIC) ensures that programs will at least run happily across the entire range of machines, so that in theory, any MSX software should run on the CX5M. Whether this will include other music programs using the SFG01's capabilities remains to be seen, but clearly there's no reason why other manufacturers shouldn't produce their own FM voicing or sequencing software, though Yamaha haven't as yet provided any indication of the entry points needed to run the SFG01. The fast-loading requirement of MSX software is achieved by providing the software in ROM form in a top-loading cartridge. Since the CX5M (or any other MSX machine, come to that) doesn't come equipped with a disk drive, this clearly makes a lot of sense, though it carries the disadvantage of cost (ROMs are more expensive to produce in smallish quantities than disks or cassettes) and in-built updating difficulties.

The software Yamaha are producing for the CX5M includes the following cartridges: YRM11 Music Macro, YRM12 FM Voicing Program, YRM13 DX7 Voicing Program, YRM14 DX9 Voicing Program, and the YRM15 FM Music Composer. Apart from the YRM12 cartridge, which is included in the £599 price tag for the CX5M, all the rest are extras costing £49 each.

YRM11 Music Macro

Problems here. I plug in the cartridge, switch the machine on, and the usual display comes up informing me that I'm using MSX BASIC Version 1.0, after which the Yamaha Music Macro takes over. Fine, but it doesn't tell me what I can do with it. Solution: look for English translation of manual. There isn't one. Panic. Flick through Japanese manual to get some gist of what's going on.

Well, from what I can see through a maze of Japanese calligraphy, Music Macro is an extension to MSX BASIC that allows all (or most) of the SFG01's formidable facilities to be used from within the user's own programs, though only by using BASIC commands. It also allows speech to be synthesised (using the keyword 'SAY'), though all attempts to get the machine to produce anything other than Japanese proved fruitless. I'd always wondered what 'onseigousei' sounded like: hope it's not rude. Trying to get it to say 'hello' only produced a stream of Japanese invective reminiscent of the worst sort of airport PA system, ie. totally unintelligible. A bit beside the point if your interests are musical, though as this also uses the SFG01, it shows once again what FM is capable of.

Conclusions: I reserve final judgement, but it should be very useful to those of a self-programming bent once the English manual has materialised.

YRM12 FM Voicing Program

Lots of menus, lots of parameters: even a command called 'Kill'. Shame Yamaha couldn't apply this to the side of this software accessed with the command 'Call Music'. The latter gives you access to the least favourable side of the CX5M's activities - auto-playing replete with rinky-dink rhythms and 'instant funk bass' patterns. Not for the faint of heart or, indeed, the musically sensitive.

Moving rapidly back to the main menu, and pressing the 'F1' function key, takes you to far more interesting territory - the edit display for the FM voices, which also allows you to play the attached YK01 keyboard. This is of the mini variety, which belongs to the school of evolution that believes in musicians adapting and growing miniature fingers. Well, you do adapt - sort of - but to be frank, this is a toy keyboard, not the real thing.

As an alternative to the YK01, there's the 'not-yet-available' YK10, which we're promised offers a full-size option for less than £100. The only problem here is that the CX5M package deal obliges you to get a YK01 first, which is a bit thick really. However, that's only one of the annoying features. Let's suppose you've got a DX7 that you want to use with the CX5M via MIDI, with the DX7 providing the velocity-sensed notes. Well, the short answer is you can't. For some bizarre reason, Yamaha saw fit to allow the MIDI In on the SFG01 module to receive only voice parameter data (in the context of the YRM13 program), not anything remotely musical. 'Grrr!' is what I say.

Still, moving on to the 46 preset voices available for use with these keyboard options. Of these, nine are excellent, about the same are bearable, and the rest should have taken an honourable way out. If it's any consolation, the excellent ones are the sort you'd use time and time again, ie. brass 1, guitar, electric bass 1, electric piano 3, piccolo, clarinet, glockenspiel (printed as 'grockenspiel', would you believe), vibraphone, xylophone, and clavinet.

Now, assuming you're of a reasonably inventive nature, you'll soon get the itch to construct your own FM voices. Fortunately, the edit side of the program makes this relatively painless - it's really just a question of using the cursor keys to send a brown box hopping around from one value to another, the numeric keys to change a value, and return to enter the same. To make things easier, a buffer store is provided so that your changed voice data isn't lost for all eternity. Your own instruments can be allocated to voices 49-96, and when you're satisfied with what you've got, the whole shooting match of both preset voices and your own can be saved onto cassette (or disk, should one become available) under the filename 'VOICE'. The idea is that this can then be loaded subsequently for consumption by the FM Music Composer program.

As far as similarities and differences to DX7/9 programming are concerned, you'll find both. One area that's considerably simpler is that of envelope generation. With the CX5M, this gets cut down in complexity to just five parameters for each Operator, ie. Attack rate (0-31), 1st Decay rate (0-31), Sustain level (0-15), 2nd Decay rate (0-31), and Release rate (0-15). But it's really no good having fancy envelopes if you can hear audible steps. So what's important to take home from this side of the FM voicing story is that the envelopes sound utterly smooth and seamless. In general, the range of all parameters is smaller, which makes for easier decision-making.

Conclusions: It's a shame the auto-playing side of the program hasn't been jettisoned for the UK market. The fact that it's still there shows (a) the original marketing angle of the YIS503 - a home micro with very advanced sound capabilities, and (b) the inflexibility of putting software onto ROM. The FM voicing side, on the other hand, looks very good. Furthermore, it shows that the sound and timbral quality of the SFG01 is right up to the standard of the DX7/9, though the noise on notes below middle C could be an annoyance.

YRM13 DX7 Voicing Program

Yamaha-Kemble claim that 'it's worth having a CX5M just for this'. Briefly, when the CX5M is powered up with a DX7 connected to the SFG01's MIDI In and Out, all the voice data in the DX7 is transferred to the CX5M and a directory of voices shows what's where. The next stage is the edit mode which, as on the YRM12 software, displays all the parameters for each voice. Here, though, we're talking in DX7, rather than SFG01 language, so there's rather more to take account of. But, let's be honest, it really does look very pretty, which is all highly conducive to an enjoyable relationship. And aside from the fact that seeing everything at once helps you to understand rather more clearly what's actually happening FM synthesis-wise, the program also allows you to spell out graphically certain areas of the DX7's programming, ie. the pitch envelope generator (sic), the envelope generator, and the keyboard scaling. All pretty useful stuff.

Other things you can do include displaying all the effect data, tranferring voice data from the CX5M to a RAM cartridge en masse, and generally taking part in all manner of loading, saving, copying, and swapping operations with the DX7.

In addition, all the voice data can also be printed out as hard copy, assuming you've got a printer to hand that will interface with the CX5M. Still, the one thing the software doesn't do is help you visualise what FM is actually doing to the sound you're hearing. I'd really love to see some software that spelled out the effect of one Operator modulating another in the shape of graphic illustrations of the resultant dynamically-changing harmonics and inharmonics. If I had something like that, I think I'd then start to appreciate just how FM sounds evolve and devolve. Perchance to dream, and all that...

Conclusions: Yes, a very useful program. But no, I wouldn't buy a CX5M just for this. On the other hand, it does make a tricky task a lot easier, looks very pretty, and the hard copy printout feature should prove invaluable for members of the DX Owners' Club and 'Patchwork' contributors!

YRM15 Music Composer

I can't pretend that I'm new to the game of putting up notes on screens and pretending that they duplicate the function of pen and paper. In fact, I remember reviewing some very similar (in intent, anyway) software from Mountain Computer back in E&MM May '81 and thinking that it was truly wonderful. To be honest, with hindsight and a lot of water under the bridge, I can see that I was duped, because although that software undoubtedly looked pretty, it was also slow, inflexible, bug-ridden, and generally everything you don't want in a supposedly interactive composing tool. Yamaha's YRM15 Music Composer cartridge, on the other hand, is simply the best I've seen on any micro. More than that, it's musical.

What the software essentially gives you is eight tracks that can be filled with up to 8359 events. How you use these tracks is really up to you, but it's important to realise at the outset that an 'event' can encompass not only a solitary note but also an indication to repeat a four-bar phrase a couple of hundred times or a host of other musical and control commands.

Still, you've got to start somewhere, and in the simplest application, you can enter a monophonic line on each of the tracks, assign a particular instrument to each line at the start, stick to the same dynamics and so on throughout, and then send the respective parts off to the CX5M's FM sound module. The typical home computer user's way of approaching composition, you might say.

Moving onwards and upwards, you might elect to put polyphonic data on each track, with voice, dynamic, tempo, phrasing, vibrato, and spatial changes sprinkled liberally from note to note, and then send some of these parts off to the FM sound module and others to other synths via MIDI, or stagger the recording of all eight tracks by using the tape sync option.

The ways in which these notes can be entered is also pretty flexible. The first option is to use the QWERTY keyboard to select durations ('1' is a semibreve, '2' is a minim, and so on) and pitches ('V' is C, 'G' is C-sharp, 'B' is D, and so on across the keyboard). Nothing wrong with that, but you need practice and patience to work out which key is what when no help is given in the way of keyboard overlays. To add insult to injury, the Music Composer software appears to have forgotten to take into account the fact that the transmogrification of the YIS503 into the CX5M saw a good deal of key position shifting, with the consequence that something of the order of 18 of the 72 key characters are in a current state of identity crisis, including such things as '_' being '=', '^' being '&' and so on. Even disregarding this cock-up, it does seem remarkably silly that a micro given the very grand label of a 'music computer' should provide so few concessions to informing the user about its relevant key functions. Why not, for instance, print the relevant musical characters on the front of the keys, as is often done with pre-programmed graphics on other micros?

The other option is a lot more sensible given the problem of identifying key functions, and that's to use the MK01 keyboard for inputting all the pitches. This works extremely well. Indeed, if you're entering a run of notes of the same duration, it's almost like a real-time transcriber, with the notes coming up onscreen virtually as they're played. In addition, you get immediate aural feedback of the note and selected instrument if you've selected the 'monitor' option. And although my first thought on seeing the MK01 was 'ugh', you get to appreciate its compact size when it's got to be sited alongside the CX5M or balanced on the lap in the manner of a detachable QWERTY keyboard. In addition, the MK01 approach to entering pitches is likely to prove marginally more comforting to the musician who's not particularly adept at reading music.

Mind you, fingers do have a habit of getting in a twist now and again, so editing facilities are essential things to have on your side. Those offered by the Music Composer program include the usual 'insert' and 'delete' modes, a bar count that's updated as you move through a part plus a 'goto bar n' feature, and, very useful indeed, a 'copy' feature that enables any number of bars to be copied from one part to another. Play facilities include either playing the entire piece, playing one part on its own, or looping all the parts. It's a shame that Yamaha didn't take this further and allow parts to be played from a particular bar rather than from the beginning. As it is, if you've filled up the CX5M's memory with all 8359 events, the only way you can hear whether an edit or sequence of notes right at the end fits in is by playing the entire piece from the beginning. Boring.

Conclusions: The combination of the Music Composer software and the FM sound module is an extremely powerful composing tool. More than that, it's also an extremely powerful production unit capable of producing multipart music with as much or as little expression and timbral variety as you like. To cap it all, the combination of the Music Composer and the SFG01 is also the most sensible way of dealing with MIDI I've seen so far, because it gets around the problem of trying to send too much information down a pipeline that's inherently too slow for complex music. And though the MK01 keyboard is a complete no-no for realtime performance, it works well for pitch input, and should help non-reading musicians get used to visualising notes on staves whether or not they choose to avail themselves of the part-by-part printout facility.

But there is one very annoying feature, and that's that instruments can't be programmed from within the Music Composer. In fact, the only way of doing this at present is to (takes deep breath) save the piece on tape, whip out the Music Composer cartridge, replace it with the FM Voicing variety (preferably with the power switched off in between!), construct a new instrument, save the entire bank of presets to a clean cassette, repeat all the cartridge operations in reverse, load up the new bank of presets, load up the afore-constructed piece, and then play it.

So, at the risk of repeating myself, I'll make the point again that it would have been a lot more sensible and professional to have scrapped the auto-play side of the FM Voicing software in favour of amalgamating the voice construction side with the Music Composer as a neat, unified whole.

System Conclusions

The end result of the combination of the SFG01 FM Synthesiser module and the YRM15 Music Composer is almost beyond reproach. Quite simply, it sounds superb. So, in theory at least, the CX5M has every chance of sweeping the micro music marketplace.

But at £599 for the package, I think that's unlikely. The stark reality is that the CX5M is a very ordinary MSX micro transformed into something special by Yamaha's prowess at FM synthesis technology. And whilst that will undoubtedly sway many musicians, I don't see the average computer buff reacting similarly. Of course, if the CX5M were priced at a level more in line with its MSX competitors, Yamaha-Kemble would be swamped with orders. And although it appears that demand for the CX5M will be more adequately met than was the case with the DX7 fiasco earlier this year, it's pretty clear that musicians alone will probably consume all the available supplies.

In short, I both envy and pity Yamaha's position!

Of course, the CX5M isn't actually in the shops yet. In fact, it's not expected until November. What Yamaha-Kemble should do in the meantime is give serious thought to correcting the shortcomings that (a) show the CX5M's music-around-the-fireside (or whatever they have in Japan) parentage, and (b) make it less than a truly professional system for the musicians that they're intending to sell it to.

To start with, the YRM15 Music Composer should be an integral part of the package deal (preferably with some means for constructing instruments within the same software), the multiple key identity crisis should be corrected, alternative key caps with music functions on the front should be provided, and a decent selection of presets and some imaginative demo pieces should be included to show what can be done with the system.

Hardly a radical rethink, but all very necessary if the CX5M is to deserve its 'music computer' label and justify the rather more professionally-inclined price tag.

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Previous Article in this issue

The Programmable Digital Sound Generator

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The Fairlight Explained

Electronics & Music Maker - Copyright: Music Maker Publications (UK), Future Publishing.


Electronics & Music Maker - Oct 1984

Donated & scanned by: Stewart Lawler

Computer Musician

Review by David Ellis

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> The Programmable Digital Sou...

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