Browse Prior Art Database

Speed Compensated Soft Sectoring

IP.com Disclosure Number: IPCOM000044783D
Original Publication Date: 1984-Aug-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Krishnamurty, R: AUTHOR [+2]

Abstract

This is a technique for establishing sector boundaries on rotating magnetic files which compensates for speed variations in the drive.

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Speed Compensated Soft Sectoring

This is a technique for establishing sector boundaries on rotating magnetic files which compensates for speed variations in the drive.

As shown in Figure 1, in a rotating magnetic storage file a sector boundary indication is generated by counting phase locked loop (PLL) clock signals relative to an INDEX file signal. The PLL clock period represents a velocity corrected data bit time from the file. The index signal, which occurs once per drive revolution, indicates that the sector count should be restarted from zero.

In the normal mode, the cyclic value register contains the bit count per sector. Each time that the counter reaches its maximum value, a carry (sector boundary) occurs and the same initial value is reloaded, thereby causing the cycle to repeat, as indicated by Figure 2.

A unique correction must be made once per drive revolution. This determines the boundary of the first sector after the INDEX signal. For this case, a special bit count associated with the GAP between the index signal and the first sector must be loaded into the cyclic value register after the last sector on the track but before the occurrence of the INDEX signal. If this condition is met the counter will be loaded with the GAP bit count value at INDEX.

This design retains the advantages of an "address mark" detection concept in that it is velocity compensated. However, in contrast with the "address mark" detection concept no complex controller is requir...