PRACTIDISK

There's no such thing as enough money or enough disk space. No matter how much capacity you have, you'll always scream for more. Practidisk, a 2.88MB disk drive completely compatible with standard PC hardware and lower capacity disks, is one among a handful of products manufactured in response to that plea.

Developed and patented by Toshiba and manufactured by TEAC, the Practidisk drive is the size and shape of a standard 3½-inch disk drive, but it uses carefully arranged barium ferrite particles and perpendicular recording technology to squeeze twice as many bits onto the tracks.

Practidisk's extremely flexible 8-bit controller card works with almost any version of BIOS and any version of DOS 2.0 or higher to control any capacity 5¼- or 3½-inch floppy disk drive installed in almost any PC-, XT-, or AT-compatible computer.

The drive and controller worked flawlessly on the AT clone I tested, but not on a Commodore Colt XT-compatible, even with a replacement card the company sent. A company official assured me that this was a very rare situation, encountered so far only with Commodore PCs.

Thanks to Practidisk's own BIOS and driver program, you can treat your 2.88MB drive as if it were just another DOS device. The only difference is that, when you format a disk, you must use a special PFORMAT command specifying the density of the disk. Once everything is set up and running, you can use, for example, PC Tools Deluxe to perform a surface analysis and optimization of your extra-high-density disk.

You can insert the drive in one of your drive bays or—for about $110 more—install an external unit, which comes with a cable with a 37-pin D connector on each end.

While doctoring regular disks for use in high-density drives is a popular way to save money, I don't recommend trying it with the Practidisk drive. The size of the tracks and the amount of power used to write data to the disk vary with capacity, and disks not designed for a given format may retain that format only temporarily, though initially they appear to perform flawlessly.

The principal anxiety involved in buying a technology that IBM has not annointed, like 2.88MB floppy disk drives, is that the standard may end up being incompatible with the hardware you have purchased. Therefore, people are interested in whether a new piece of technology has industry support. The manufacturers of Back-It support the 2.88MB format. Extra-high-density disks (virtually identical in appearance to high-capacity disks but marked with the letters ED) are available from 3M (I found them for $32.50 apiece), Maxell (slated to list at $162.85 for a 10-pack), and Toshiba. Practical Computer Technologies sells the extra-high-density disks for a bargain—$7.00 each. If, at some point, these disks lose favor to some other extremely high-density disk standard, the Practidisk drive won't be obsolete because it will still be used with 720K and 1.44MB disks and any 2.88MB disks you have on hand.

ROBERT BIXBY