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High Track Density Floppy Disk File

IP.com Disclosure Number: IPCOM000046722D
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 13K

Publishing Venue

IBM

Related People

Nassimbene, EG: AUTHOR

Abstract

This proposal is aimed at increasing the number of tracks on a floppy disk. In floppy disk systems, there are two major problems which make reading higher densities a significant problem: (1) the mechanical misregistration caused by the tolerance buildup of the disk registration and the head-positioning mechanism, and (2) the asymmetrical expansion of the MYLAR* disk as a result of temperature and humidity. The present approach utilizes an unusual servo concept - a mapped tracking concept. The idea is that once the disk is in place, the shape of the outer track (the one that can be affected most by tolerance buildup and disk expansion) is mapped into a servo memory. This information is then used to position the head to the optimum position for reading the various segments around the disk.

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High Track Density Floppy Disk File

This proposal is aimed at increasing the number of tracks on a floppy disk. In floppy disk systems, there are two major problems which make reading higher densities a significant problem: (1) the mechanical misregistration caused by the tolerance buildup of the disk registration and the head-positioning mechanism, and (2) the asymmetrical expansion of the MYLAR* disk as a result of temperature and humidity. The present approach utilizes an unusual servo concept - a mapped tracking concept. The idea is that once the disk is in place, the shape of the outer track (the one that can be affected most by tolerance buildup and disk expansion) is mapped into a servo memory. This information is then used to position the head to the optimum position for reading the various segments around the disk. Mapping Procedure When the disk is first put on (and at later times specified by the user or under machine control), the outer track is mapped by positioning the head to the outer edge of track 'o' and noting the amplitude of the signal in several equally spaced places around the disk. The head is then moved 1/4 of the width of a track, and the same procedure is done; this is repeated until the head is off the track. By storing which head position has the greatest amplitude at each of the reference points around the disk, the computer can determine how to position the head in order to accurately follow the track. A simple algorithm is used to determine the proper head position between sample points and from track-to...