DiscXchange. (hard drive) (Evaluation)
by Bruce M. Bowden

Daunted by the prospect of installing a hard drive? Interpreter simplifies the process with DiscXchange, and externally mounted hard drive complete with software that assigns drive letters and does your formatting for you.

The unit has several interesting features. It hooks up to your computer through the standard IBM parallel (printer) port. The disks aren't built in but are contained within roughly 5 1/4-inch square x 1/2-inch thick removable cartridges. You can change 44MB or 88MB cartridges as easily as you might change floppy disks. Though it requires a 120-volt power outlet, the unit itself is easily transportable, weighing seven pounds and measuring 6 1/2 x 2 1/2 x14 inches. It even has a carrying handle.

The DiscXchange driver software automatically assigns device letters which fall beyond those of the computer system to which the unit is connected. The driver software is completely transparent--use these drives like any other drives in your system, because all the DOS commands and routines apply. Disk access is reasonably fast--as much as 127 KBps, with an average seek time of 20 ms. Add to this self-diagnostics, built-in defect management, and automatic error correction, and you have a unit that's a real contender!

Unfortunately, getting started can be a problem. I used an XT-compatible desktop clone on my first attempt to install DiscXchange. The software provided (in both 5 1/4- and 3 1/2-inch low-density floppy disk formats) contains a TSR routine, DX44, which automatically assigns drive letters to DiscXchange that follow those of the host computer's resident drives. My XT has the equivalent of six drives, A-F, two of which are hard drive partitions. When the DX44 program was first run, a message appeared indicating that a communications problem existed, something possibly related to my parallel port. But the DiscXchange active light came on during all this, causing me to suspect that the real problem was an unformatted hard disk cartridge.

Because of this suspicion, I loaded another file from the installation disk, SQPREP, to do formatting. (There are two low-density installation disks provided for both 3 1/2- and 5 1/4-inch disk drives.) A message appeared on the screen asking for the non-SCSI drive count. It wasn't asking how many hard drives I had, but whether my partitions would count as one or two hard drives. To play it safe, I decided to use my XT-compatible laptop, which has two floppy drives and no hard drives. After loading the installation program and then the formatting file SQPREP, I chose the No Non-SCSI Drives option and followed the default selections. The 88MB cartridge was correctly formatted with three partitions--two of 32MB and one of 24MB. The drive letters became C, D, and E, as was appropriate for my two-drive unit.

Reattaching DiscXchange to my desktop, I loaded the driver software. Magic! Not only was DiscXchange recognized and accessible, but the drive letters were automatically assigned after the letters already in use. I now had a G, and H, and an I drive--just what I was supposed to have. Because operation of the DX44 driver is completely transparent to the user, copying files to DiscXchange and running software is a completely natural process with no hitches at all.

I'd love to have a DiscXchange unit to keep. It's fast, easy to use, reliable, and convenient.