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Browse Prior Art Database

Sector Pulse Shifting to Minimize Disk Drive Track Skew

IP.com Disclosure Number: IPCOM000105732D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Anderson, CA: AUTHOR [+4]

Abstract

A method for minimizing disk drive track skew through the shifting of sector pulses is disclosed.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 78% of the total text.

Sector Pulse Shifting to Minimize Disk Drive Track Skew

      A method for minimizing disk drive track skew through the
shifting of sector pulses is disclosed.

      In a drive with multiple disks, a track switch operation
involves electronically switching from one read/write head to the
next, and possibly moving the head/actuator assembly to compensate
for mechanical shifting between adjacent disks.  These actions
require a finite amount of time which should be minimized to reduce
processing overhead time, thereby improving system performance.

      A technique commonly used to reduce track switch overhead is to
introduce "track skew."  Disclosed here is a method of minimizing
track skew by "shifting" the INDEX and SECTOR pulses on the next
track relative to their positions on the current track.

      Consider the hardware logic shown in Fig. 1.  A Clocked Delay
Circuit receives the INDEX and SECTOR signals as inputs and delays
them by some number of CLOCK cycles, producing the outputs labeled
INDEX_DELAYED and SECTOR_DELAYED.  The number of CLOCK cycles used to
produce the delay is obtained from the microprocessor-programmable
Delay Count Register.  This allows flexibility in tuning the delay
for various sector size configurations, and also allows the delay
from a nominal position to be varied from surface to surface for
multi-platter disk drives.

      Now consider the diagram shown in Fig. 2.  The position of the
sectors on Track 1 is deter...