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Browse Prior Art Database

Magnetically Encoded Index Mark

IP.com Disclosure Number: IPCOM000047010D
Original Publication Date: 1983-Sep-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Herald, RF: AUTHOR [+2]

Abstract

The beginning of each recording track, of a flexible magnetic recording disk, is identified by a magnetically encoded index mark. The figure shows a floppy disk 10 whose multiple recording tracks lie in a zone 11, 12. A circumferentially-stationary magnetic read/ write head 13 can be radially positioned to transduce any selected track, as the disk rotates about axis 14. Each track includes one index mark (IM) 15 and a plurality of ID/data field zones 17 about the track's 360Πcircumference. Each individual zone 17 includes an identifier (ID) and a data field. To accomplish various functions (such as "ID NOT FOUND IN ONE DISK REVOLUTION") within the disk drive controller, it is necessary to know when a revolution of the disk has occurred. The magnetic transitions of each track's IM field are read by head 13.

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Magnetically Encoded Index Mark

The beginning of each recording track, of a flexible magnetic recording disk, is identified by a magnetically encoded index mark. The figure shows a floppy disk 10 whose multiple recording tracks lie in a zone 11, 12. A circumferentially- stationary magnetic read/ write head 13 can be radially positioned to transduce any selected track, as the disk rotates about axis 14. Each track includes one index mark (IM) 15 and a plurality of ID/data field zones 17 about the track's 360OE circumference. Each individual zone 17 includes an identifier (ID) and a data field. To accomplish various functions (such as "ID NOT FOUND IN ONE DISK REVOLUTION") within the disk drive controller, it is necessary to know when a revolution of the disk has occurred. The magnetic transitions of each track's IM field are read by head 13. The head's signal is amplified, converted to a digital serial bit stream, and then decoded by circuits within the disk drive controller. Output signal 19 provides a start of track signal which is used by other circuits (not shown) within the controller. With this arrangement, there is no need for the beginning (IM) of the various tracks to be radially aligned, but rather, the track beginnings can be circumferentially scattered about the surface of the disk.

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