Browse Prior Art Database

Defective Sector Relocate in a Flexible Disk Recorder

IP.com Disclosure Number: IPCOM000046280D
Original Publication Date: 1983-Jun-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Bendsten, DL: AUTHOR [+6]

Abstract

In a flexible disk recorder where the sectors are formatted so that there are two identifier (ID) fields plus a data field, the identifier fields may be used as pointers to point forward and backward between defective sectors and relocated sectors. In addition, the ID field for the pointer to the relocated sector may be located at any defect-free position in the defective sector.

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Defective Sector Relocate in a Flexible Disk Recorder

In a flexible disk recorder where the sectors are formatted so that there are two identifier (ID) fields plus a data field, the identifier fields may be used as pointers to point forward and backward between defective sectors and relocated sectors. In addition, the ID field for the pointer to the relocated sector may be located at any defect-free position in the defective sector.

Shown above are two examples, A and B, of defective sectors and rewritten defective sectors. A normal sector includes three fields of information. Each field begins with a unique address mark and is separated from adjacent fields by a gap in the recording. The first field contains a Diskette Identifier (DID) and a Sector Identifier (SID). The second field contains the Logical Identifier (LID) or Record Identifier. Normally the SID and LID are identical. The third field is the data field.

In example A1, the data field contains a defect. The controller for the diskette drive causes the drive to rewrite the LID field with a pointer to the relocated sector. This is shown in example A2. The rewrite of the LID is simply the new SID pointer to the relocated sector. The relocated sector is shown as example C above. The DID field of the relocated sector contains the SID to which the defective sector now points. In the LID field of the relocated sector, the old LID (LID from the defective sector) is written. The data for the old LID is then wri...