SuperDisk Technology

One of the first removable-media drives to break the 20MB barrier and maintain backward compatibility

with standard 3 1/2'' media was a drive made by a company called Insite Peripherals in the early

1990s. Its patented floptical technology used optical tracking to precisely align the magnetic

read/write heads of the drive, which could store a then-amazing 21MB in the same form factor used

by a 1.44MB 3 1/2'' drive.

The performance specifications of the drive (average access time of 65ms, transfer rate of 1.6MBps,

and rotational speed of 720rpm) are similar to those used by higher-capacity drives today. The Insite

Peripherals floptical is a direct ancestor of the Imation LS-120 SuperDisk, which uses an advanced version

of the same head-positioning techniques. Both the now-obsolete Insite floptical and the LS-120

are capable of reading, writing, and formatting standard 3 1/2'' 720KB and 1.44MB floppy disks, but

the relatively unpopular 2.88MB floppy is not supported.

The read/write heads of a floptical drive use magnetic recording technology—similar to that of floppy

disk drives—and the floptical disk itself is composed of the same ferrite materials common to floppy

and hard disks. Floptical drives are capable of such increased capacity because many more tracks are

packed on each disk, compared with a standard 1.44MB floppy. Obviously, to fit so many tracks on

the floptical disk, the tracks must be much narrower than those on a floppy disk.

That’s where optical technology comes into play. Flopticals use a special optical mechanism to properly

position the drive read/write heads over the data tracks on the disk. Servo information, which specifically

defines the location of each track, is embedded in the disk during the manufacturing process. Each track

of servo information is actually etched or stamped on the disk and is never disturbed during the recording

process. Each time the floptical drive writes to the disk, the recording mechanism (including the

read/write heads) is guided by a laser beam precisely into place by this servo information. When the floptical

drive reads the encoded data, the laser uses this servo information again to guide the read/write heads

precisely into place. The use of servo information is not unique to flopticals; hard drives have used servo

tracks for years, but the use of a laser beam to read the servo tracks is what makes floptical drives unique.