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Multi-Track-Density Floppy Disk System

IP.com Disclosure Number: IPCOM000042010D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Nassimbene, EG: AUTHOR

Abstract

The desire in the floppy disk industry is to get more tracks per inch on a disk without significantly increasing the cost. The primary problem that limits the number of tracks per inch is the expansion of the disk with temperature and humidity. The 8-inch disks typically use 48 tracks per inch (TPI), the 5-inch disks are at 96 TPI, and the 3-inch disks approach 150 to 200 TPI; the smaller the disk the higher the track density because the amount of linear expansion of the disk is smaller. The system to be described is one in which two or more track densities are written on the same disk, with the outer tracks being further apart than the inner tracks. For example, one configuration could be on an 8-inch disk where the tracks from 8 inches to 5 inches are 48 tracks per inch and those from 5 inches to the inner track are 96 TPI.

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Multi-Track-Density Floppy Disk System

The desire in the floppy disk industry is to get more tracks per inch on a disk without significantly increasing the cost. The primary problem that limits the number of tracks per inch is the expansion of the disk with temperature and humidity. The 8-inch disks typically use 48 tracks per inch (TPI), the 5-inch disks are at 96 TPI, and the 3-inch disks approach 150 to 200 TPI; the smaller the disk the higher the track density because the amount of linear expansion of the disk is smaller. The system to be described is one in which two or more track densities are written on the same disk, with the outer tracks being further apart than the inner tracks. For example, one configuration could be on an 8-inch disk where the tracks from 8 inches to 5 inches are 48 tracks per inch and those from 5 inches to the inner track are 96 TPI. If a 5-inch disk is used, the outer tracks would be 96 TPI, and the inner (from 3 inches inward) would be 192 TPI. The stepping motor would be set to step to the narrowest track spacing; on the outer, lower density tracks it would make two steps to move from track to track. Obviously, the disk may contain more than two sets of track densities if a head with more than two Read/Write gap widths is made. The ultimate configuration and the one which will produce the greatest number of tracks per disk is one in which the track width continually varies in size from the outside to the inside of the disk. This...