There are two things you can never have enough of. The other one is hard disk space...

One of the first laws of computing is that your data will expand to fill the available storage space. And then some. Having recently upgraded my Mac from a 40Mb to a 100Mb internal hard disk, it didn't take long to fill it. I put the 40Mb in an external case and that's getting rather full too, although I tend to hive stuff off onto it which I think I won't need as much as the stuff on my main disk. Of course, I'm usually wrong but that's what you get for trying to flaunt another basic computer law: nothing you want is ever on the first disk you look at.

I also have System 7 on the 40Mb drive so if I want to use it, I simply boot up with the drive switched on. Otherwise, good old System 6.0.7 on my main disk works fine. It's faster than System 7, it uses less memory than 7, all the programs I have work with it and I haven't had to fork out for expensive System 7 savvy upgrades. Still, I expect I'll upgrade when System 7 v2 arrives. Can't remain a Luddite forever.

So is this enough storage space? Of course not! I had already bought a removable hard disk which conveniently doubles as yet another Mac drive and also as storage for samples for my S1000. I recently upgraded the S1000 memory to 10Mb and even high density floppies just aren't up to the job of storing the amount of data in a typical program.

Why am I telling you the story of my drives? Mainly to reinforce the statement I made at the beginning of this article but also to lead nicely into the review of the piece of gear pictured above. It's actually a box containing two pieces of gear, a removable disk drive and a CD ROM drive. The box is a 2U rackmount unit and I've never felt anything so heavy in all my life. Japanese Sumo wrestlers may be heavier - but I'm not so sure.

Dynatek is a Canadian company which produces fixed and removable hard drives, CD ROMs, optical drives and DATs. As many operations benefit from two or more systems, Dynatek hit on the bright idea of producing combination drives, mixed and matched to various requirements. For example, if you're an avid sample user, it makes sense to combine a CD ROM drive (from which you can load samples) with a hard disk (onto which you can save complete programs). More about this in a moment...

The hard drive and CD ROM in the CDR688 are, to all intents and purposes, two completely independent units which share nothing more than a box and a power supply. There's nothing to suggest that you've bought a single unit. They each have two SCSI sockets and you have to connect these just as you would any two independent units. The SCSI ID numbers are easily set and seen from the front panel - which is where they should be. There's nothing worse than having to mess around at the back of the gear in a rack.

The cable supplied to connect the Mac to a SCSI device (the Mac end of the cable, of course, is not the same as a standard SCSI socket) is a tad over 3' and just simply wasn't long enough to conveniently site the unit where I wanted it. The SCSI to SCSI cable is a meagre 2'. However, the SCSI to SCSI only has to run a few inches across the back of the unit so that's fair enough.

So, you plug in, switch on and boot up. The Dynatek Drive Utilities disk contains a formatting program and tells you what other devices are connected to your SCSI port.

There are two common removable hard disk sizes 44Mb and 88Mb. The Dynatek has 88 on the front and you get an 88MB cartridge to start you off. The technical spec in the manual (dated 1990), however, simply refer to a 44Mb capacity which suggests that the design has been updated but the manual hasn't. Having said that, Dynatek also produces a 44Mb version so perhaps they're just being economical with trees and manual writers.

The access time of a hard disk will generally only be of major concern if you are shifting lots of data such as graphics and DTP files - or wish to do direct-to-disk recording. The specs quote an average access time of 20 milliseconds, which is on the good side of average for a removable disk.

Direct-to-disk recording has got to be one of the main attractions of a removable hard disk to the musician, but the process does demand that the disk is capable of transferring data at a certain rate. Direct-to-disk recording systems will usually state the minimum speed requirements. For example, Mark of the Unicorn's Digital Performer requires a drive with an access time of 20 milliseconds or less. That's faster than your average removable hard disk and even faster than some fixed drives. Some direct-to-disk systems may be more lenient, especially if they have dedicated hardware to take care of the data transfer, although the success of this is also dependent on the computer's speed.

It's also worth pointing out that some of the cheaper removable drives may not be quite as reliable as you might like. While this may not affect normal use (it can always have a second go at reading data) it may adversely affect digital recording. The point of all this is simply to ensure that you buy the right tools for the job. Of course, there's nothing to stop you recording to a fast internal disk and then transferring the data to a cheap removable drive.

Dynatek obviously expect their units to be used with direct-to-disk systems and have tweaked their drives to run at the optimum speed. Sound Technology (the UK distributors) have a compatibility chart which shows the Dynatek removable hard disk to be compatible with most of the major D-t-D systems including Digidesign's Pro Tools, Hybrid Arts' Digital Master, Roland's DM80, Akai's DD1000 and Yamaha's D5. It's also compatible with all the major 16-bit samplers from Akai, Roland, E-mu, Ensoniq, Kurzweil, Digidesign and Casio - but then you'd expect it to be.

The drive worked fine in use. It's a lot quieter than my (cheapo) 44Mb removable drive and it appeared to work faster, too, although that's only a subjective impression.

The CD drive in the Dynatek unit is a Sony CDU 541 which, in a recent Mac mag test, proved averagely fast in comparison with a bundle of other CD ROM drives. The quoted access time is 380 milliseconds. The compatibility table claims it's compatible with all the samplers mentioned above except the Casio FZ20M although I don't know why this should be so as you can, surely, simply play the thing and sample into any sampler.

The unit has a headphone socket and left and right audio outs (phonos) but no digital outs which I find surprising, especially for a unit which is such an obvious choice for the sampler user. However, I must confess I've never bothered to get a digital interface for my S1000. Audio samples, especially from CDs and DATs, go in very cleanly so do I need digital, I ask myself? And so must you.

You insert the CD into a removable caddy and slip it into the unit. There's a volume control on the front for the headphones and an eject button but the controlling software will often override this.

An OMCD (OPTICAL Media) device driver is used to control the player. This has it's own short manual. You basically drop a few files into your System folder, restart and off you go. The software is compatible with System 7 and lets the Mac read CDs in the same way as it reads floppy and hard disks. CD ROM and audio CDs appear on the desktop with slightly different icons. There are two main CD ROM formats - High Sierra and ISO 9660 - although they are virtually identical. They are supported by the access files you drop into your system folder. There's one for audio CDs, too.

One of the main uses of CD ROM for the musician is to be able to play your CDs while you're working on your computer... okay, perhaps not. But you can play audio CDs on them, and buying this device saves you splashing out a separate CD player - although your Mac must be switched on in order for it to work and you can't plug in a set of phones and take it with you on the tube.

An audio CD player HyperCard driver called Play CD (you'll need HyperCard v2) is supplied in a folder called Unsupported Goodies. You are prompted for the name of a new CD as you load it and you can type in the names of the tracks and create a play list if you wish. It works but I found it very slow and sluggish and really not a very inspiring sort of program. Apple's CD Remote which runs as a DA works far better. (Incidentally, I found this on one of a number of CDs loaned by Tailor Made Solutions, thanks chaps).

The other major use of a CD player is, of course, for sampling; everyone seems to be releasing sample CDs these days, and there's also a growing market in CD multi-media disks. Controlling a sample CD from your computer is very convenient. You can name the tracks - which means you don't have to refer to the manual - and, well, if you're anything like me, you get a certain satisfaction from controlling equipment by remote. Having everything under your fingertips as it were.

Yet another use of CDs is simply to store large amounts of computer data such as programs, data files and games. Can you imagine a game which contained 650Mb of data? Mega! There are already quite a few on the market including adventures and game collections. Some, such as Spaceship Warlock, are described as 'interactive movies' and use the massive amount of data to create walk-though scenes.

There are also many educationally-oriented CDs and CDs of PD and Shareware which are generally very cost-effective - although most tend to be 'of an age'. CDs are also very good at storing databases such as encyclopaedias, atlases and newspaper and magazine back-issues. All this data is instantly accessible. If you work with pictures imagine having instant access to 650Mb of clip art? Companies are also putting entire font collections onto CDs. You unlock each font by phoning the company, giving them your credit card number and they respond with a special code.

Typical CD prices range from around £30 for certain games and data collections to over £200. Some can cost two or three times this amount. An average is probably £75-100.

The downside of CD ROMS is that they are slow. Compare the 380 millisecond access time to the 20 millisecond access time of a hard disk. If you are reading a lot of data it could take 20 times as long as it would if it was stored on a hard disk. However, there are CD ROM utility programs which can help speed up CD ROM use.

CD ROMs are also read-only. I mention this just to remind you. If you want to alter some data you'll have to save it elsewhere, I'm afraid. If you need large amounts of writable storage space, you need to look at writable optical drives which can store 128Mb of data on a 3.5-size disk. These have a slower access time than removable drives but some are compatible with certain direct-to-disk recorders. But CDs have many uses and applications for the computer user and musician and will no doubt continue to grow in popularity as a storage medium - especially as CD ROM prices fall.

Which brings us to the price of the unit. It's certainly not cheap by any stretch of the imagination; None of the Dynatek units are. They even quote a list price of £130 for an 88Mb cartridge which is almost twice the 'street' price. And on a picky note, at this sort of price, the documentation should be better.

The same Sony CD ROM drive in a stand alone unit from another manufacturer might cost around £600. An 88Mb removable drive can cost from £600-800. Both prices are list, not street. The removable drive Dynatek uses is a Syquest SQ5110 and, oddly, in its publicity, Dynatek claims Syquest has had a reputation for unreliability! Well, there's honesty for you. However, the company offers a two-year warranty on the drive and one year on the cartridge - which must do something to (re)instil a sense of faith in them. The CD ROM player is guaranteed for one year.

Clearly, what you are paying for is quality and performance. Most of the removable drives from other manufacturers quote an access time of 22 milliseconds or more. Whether Dynatek have tweaked the drives or are using a different set of measuring criteria to time it, who knows, but they do guarantee that it will work with a wide range of direct-to-disk recording systems and samplers. So if this is what you have in mind, it could pay to play safe.

I know from experience that my cheapo 44Mb removable drive sometimes needs a couple of tries to read and write data from and to the S1000 although - touch wood - I've never lost any data with it. But having lost data in other ways, I know what a bummer it is. You pays your money and takes your choice. The units work well and are (very!) solidly built and housed but to reach a mass market, someone really needs to look closely at the price. I'll happily report on their long-term reliability in a couple of years' time...