Browse Prior Art Database

Providing Additional Id Read Capability to Allow a Single Id With Magnetoresistive (MR) Head

IP.com Disclosure Number: IPCOM000119446D
Original Publication Date: 1991-Jan-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 1 page(s) / 54K

Publishing Venue

IBM

Related People

Cunningham, EA: AUTHOR

Abstract

In Direct Access Storage Devices (DASDs) using magnetoresistive (MR) heads for reading, where the write structure has some physical separation from the read element, a difference in access position occurs for the optimum read and write positions, when the heads are moved with a rotary actuator. Since it is desirable to have one sector identification field to read before the read or write of each sector, the field must be read with the head either in the optimum data read position, or the write position. Disclosed is a method to provide additional read capability of the identification fields to allow proper operation with the additional stress of differing offsets.

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Providing Additional Id Read Capability to Allow a Single Id With
Magnetoresistive (MR) Head

      In Direct Access Storage Devices (DASDs) using magnetoresistive
(MR) heads for reading, where the write structure has some physical
separation from the read element, a difference in access position
occurs for the optimum read and write positions, when the heads are
moved with a rotary actuator.  Since it is desirable to have one
sector identification field to read before the read or write of each
sector, the field must be read with the head either in the optimum
data read position, or the write position. Disclosed is a method to
provide additional read capability of the identification fields to
allow proper operation with the additional stress of differing
offsets.

      The first step in providing proper read capability of single
identification fields is to position them approximately midway
between the optimum read position and write position of the head, so
that the maximum offset of the read element from the written
identification field is minimized.

      The next step is to guarantee that any interference adjacent to
the identification field is eliminated, by direct current erasure
between nominal track positions before the identification fields are
written.  In normal testing of the DASD, there can be test patterns
written off center from the nominal positions.  The residual
interference of such patterns is eliminated by the erasure.

      Heads wi...