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Initial Track Acquisition for a Disk File

IP.com Disclosure Number: IPCOM000043172D
Original Publication Date: 1984-Jul-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Case, WJP: AUTHOR

Abstract

When a disk file is initially powered up, Track 0 is acquired by using servo position error information written in the guard band firstly to position the head over the nearest track of the same type as Track 0. If this track is not Track 0, controlled steps of a fixed number of tracks at a time are performed until the Track Identifier (ID) of Track 0 is read. Normally, on power up, the read/write head is positioned at a limit of its movement, as defined by the physical abutment of the head actuator with an end stop. For a file employing servo head positioning, this means that the head will be within a guard band, i.e., a region of the disk which is not available for data recording and which is distinguishable from the data area.

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Initial Track Acquisition for a Disk File

When a disk file is initially powered up, Track 0 is acquired by using servo position error information written in the guard band firstly to position the head over the nearest track of the same type as Track 0. If this track is not Track 0, controlled steps of a fixed number of tracks at a time are performed until the Track Identifier (ID) of Track 0 is read. Normally, on power up, the read/write head is positioned at a limit of its movement, as defined by the physical abutment of the head actuator with an end stop. For a file employing servo head positioning, this means that the head will be within a guard band, i.e., a region of the disk which is not available for data recording and which is distinguishable from the data area. Before read or write operations can take place, it is necessary to position the head accurately on one of the data recording tracks, usually known as "Track 0" or the "home track". If the guard band as well as the data area is provided with servo position information, e.g., of two phases in quadrature, the position of the head will be known within a band of two tracks. The head is then moved by an appropriate fraction of two tracks in a direction away from the end stop to position it over the center of the nearest track of the same known type (odd or even) as Track 0. The file then attempts to read the identifying information (ID) which uniquely identifies every data track. If the head is still wi...