It must have occurred to some fiendish mind at Casio that the basic design of the electric guitar hasn't changed for around 30 years. Goodness knows what they'll come up with when the Casio design technicians sit down to redesign the instrument from scratch.

Meanwhile — probably to the relief of guitar manufacturers — the inscrutable Orientals are concentrating on portable keyboards and synthesizers. Casio are largely responsible for dragging keyboards out of the hands of the Wakemans and Emersons of this world. Attitudes to keyboards have changed beyond all recognition — no longer will a musician say "I can't afford it, and even if I could, I couldn't understand it." These days, the question isn't "have you got a Casio?" but "How many Casios have you got?".

Starting from the pocket VL-1 with its maddening in-built Hungarian folk tune, to the CT full-size keyboards, the MT and PT mini keyboards, and now the CZ synthesizers, Casio have single-mindedly dragged the keyboard market kicking and screaming into the 80's with cheap equipment and increasingly professional sounds. Some musicians are even using them on stage without sticking tape over the legend CASIO.

I suppose it was inevitable that Casio would turn to more esoteric devices such as sequencers once the more advanced synths, such as the CZ-101 and CZ-5000, were established.

The CZ synths are, as most of you will know, wonderful devices using the Yamaha-DX-like Phase Distortion sound production method. Fully MIDI compatible, and with a modern range of options such as cartridge sound storage, internal patch editing, and tone mix, they offer digital/analogue sounds at affordable prices — and, in the case of the CZ-101, maximum portability. Just about the only thing they won't do is play themselves — and someone at Casio obviously spent long nights worrying about this. Fortunately the worry is now over.

One of the major differences between Casio's CZ-101 and its big brother, the CZ-5000, (apart from the larger keyboard and eight extra voices of the 5000) is the 5000's on-board sequencer. In their infinite wisdom, a cut-down stand-alone version of this sequencer has now been made available in the form of the SZ-1.

The SZ-1 is a four-note polyphonic MIDI sequencer, the cheapest to emerge so far. Though it does make some compromises on facilities compared to, say, Roland's MSQ-700 or the PolyMIDI-1, it should offer an easy entry to MIDI sequencing to many synth owners.

Roland's MSQ-700 costs around £700, and the Micro Performance PolyMIDI One around £499, so the delights of MIDI sequencing have been denied to many poor but honest punters. At £245 the SZ-1 doesn't leave you with much excuse — now anyone with a MIDI keyboard and no MIDI sequencer can justifiably be scorned and insulted in the streets.

The unit can't be said to be impressive visually; a grey plastic box 325x64x220 millimetres, styled to match the CZ synth series, weighing 11 gg, and featuring grey and blue touch switches.

To the top left of the front panel is the LCD display which gives most of the necessary status indications. It's very difficult to read in low light, but that's a fault shared by many instruments including the revered Yamaha DX7. So what can the SZ-1 do that can't be done with your fingers?

As usual the best way to find out is to look at the numerous knobs and sockets.

On the back of the unit are a cartridge port, 7.5 volt DC power socket, start footswitch socket, a tape dump DIN socket, two MIDI outs and one MIDI in. The two MIDI outs are necessary because the CZ synths (among others) aren't supplied with MIDI THROUGH sockets. Unless you own a through box, this would make life difficult for multikeyboard owners were it not for the dual sockets on the SZ.

The SZ can also be powered by five 1.5 volt batteries, making it an ideal match for the portable CZ-101. The prospect of flat batteries on stage is a fairly grim one, so I wouldn't rely on them overmuch; however, you'll need to leave batteries in the SZ1 to preserve its volatile memory.

The tape dump facility is a back-up for the cartridge storage system which most users will probably find preferable. Complete sequences can be dumped and reloaded instantly using the optional RA5 memory cartridges. There's no indication yet as to how much these cartridges might cost, though, and tape is cheap. The tape dump facility has Load, Save and Verify functions, but again it would be a brave man who would rely on tape loading in an on-going performance situation. A full memory set can be loaded from tape in around a minute, but wouldn't it be nice to have an option to dump information to, say, a Commodore 1541 disk drive? This may be a possibility soon, since Passport Software has already developed a CZ-101 patch dump program, and an SZ-1 data dump package should present few problems. Alternatively,you could just rely on the chunky cartridges; storage modes are selected using the Cartridge/MT switch on the top right of the main control area.

On the back of the SZ is the Touch Data On/Off switch, which, as its name suggests, allows you to select whether memory-eating touch information is recorded or not. Obviously you won't be wanting to record it if you don't have a touch-responsive synth, silly boy.

Also mounted on the back panel is the Clock Ext/In switch, which allows you to select whether the tempo of the sequencer is controlled by another sequencer or a drum machine, or by its own internal tempo setting.

Once your synths and/or drum machines are connected up to the SZ, you'll find that there are two sequence recording modes and four track selectors. As you'll know, (skip this bit, those of you who can plug MIDI cables in the right way around with your eyes closed and your hands tied behind your backs), MIDI supports up to 16 control channels, along which note information can be passed independently. Before starting to record, you can select the channel used by hitting the MIDI button and using the UP/DOWN buttons (which, together with the ENTER key, control most information entry). The result appears on the LCD display.

Recording in real time is dead simple — just press Record/Real Time and PLAY, and away you go. There's a metronome click for you to synchronise your performance to, but it's pretty quiet, and inaudible if, for any reason, you're monitoring on headphones. A flashing LED would have been nice. As you play, the LCD display counts off bar numbers.

Just in case you make some mistakes, there's a 'punch-in' feature by which you can drop in to replay a specific portion of the sequence, then drop out again once your correction is complete.

Once you've finished recording a track, you use the controls as you would a tape recorder. REV counts backwards through the bar numbers to return you to bar zero. It's just as simple to use FWD to count forward through the bars, and STOP once you've located the right section.

Having finished one track, you can re-select from the four track buttons (each one of which has an LED which lights when its active) and lay down your next track. This can, of course, be recorded using a different MIDI channel, which opens up the possibility of running four different synths off the SZ-1 simultaneously. Some synths, such as the CZ series, can play four different sounds monophonically on different MIDI channels, ('multi-timbral' or 'mono mode'), making it possible to build up a complete 'backing track' with a solo lead line, just using the CZ and SZ sequencer. Pretty neat. In step time, or Manual mode, the SZ's left-hand control group is used. Notes are entered from the synth keyboard, and the note length set using the nine time keys and Rest button. It's obviously slower to use than realtime, but gives gratifyingly precise results.

One great advantage of step time is that it facilitates bar copying. Rather than enter the same bar over and over again, you can use the Insert, Delete and Copy key to build up compositions from a 'library' of sequences. It's also possible to use the overdub function to add to existing sequences, though you have to be aware that there's a danger that you might run out of voices to play with. Total memory capacity is around 1800 notes, so you're not going to be recording any symphonies; but I would anticipate larger versions of the SZ in due course, probably with eight-channel polyphony and double the memory, as featured on the CZ-5000's onboard sequencer.

As with all digital sequencers, a lot of pleasure is derived from the ability to build up a step-time sequence, or lay down a realtime performance slowly, and to hear it played back at breathtaking speed with no mistakes whatsoever. In the case of the SZ, your tempo is variable from 40-256 BPM, which should be satisfactory for most users. As discussed earlier, you can also control tempo from external drum machines or sequencers, giving the option of programmable tempo which is absent on the SZ1.

There are lots of extras which indicate the amount of thought put into the SZ. The Auto Power Off option, for instance, will preserve your precious batteries should you leave your device humming quietly to itself, by switching it off if no operations have been carried out for several minutes. You can deselect the APO facility if you prefer, since it can be disconcerting to find that the machine's switched itself into sulking mode if you neglect it.

Casio's plan for world domination is based on the Cosmo synth project constructed for Japanese musician Isao Tomita. Each idea incorporated into the giant Como is being developed separately in commercial form. The Phase Distortion synths and SZ sequencers are the first two projects; next up will be a digital drum machine and sampling keyboards. I think it's safe to say that they'll be a great success.

As for the SZ-1 itself, it's an excellent intro to MIDI sequencing, ideal for CZ-101 owners and probably adequate for most single-keyboard users. It probably wouldn't be powerful enough for large multi-synth systems, or for extensive live performances. But God knows what will happen when the buskers get their hands on it.

RRP: £245