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Tangential Track Disk Recordings

IP.com Disclosure Number: IPCOM000083250D
Original Publication Date: 1975-Apr-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Schick, T: AUTHOR

Abstract

Described is a track arrangement for disks, which is capable of reducing seek time at a cost of reduction in data capacity and more complex head movement.

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Tangential Track Disk Recordings

Described is a track arrangement for disks, which is capable of reducing seek time at a cost of reduction in data capacity and more complex head movement.

The data tracks on the disk D may be defined as eccentric circles being tangent at one point and are illustrated in Fig. 1. The seek time is reduced by virtue of the fact that all of the tracks pass through the same point. With this arrangement, the average time to access data anywhere on the disk is one revolution. The maximum time to access data anywhere is two revolutions and the average time to access data on the same cylinder is one-half revolution. In no event, however, may the diameter of the innermost track be equal to or less than the radius of the outermost track.

Servo tracks are required since the data tracks cannot be manufactured as perfect circles and these, like the data tracks, merge at the point of tangency where they become indistinguishable. If two tracks only are used, the two servo tracks may be written with different frequencies. The number of multifrequency servo tracks may be increased to handle more than two tracks, by expanding frequency pairs as track pairs become distinguishable beyond the point of tangency, at which point data may be resident. The distance from the point of tangency where this condition will prevail is a function of the number of tracks provided.

In addition to the above, the number of tracks provided will be limited by the permissi...