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Scheme for Establishing a Track Reference After the Completion of a Seek Operation On a Storage Device

IP.com Disclosure Number: IPCOM000120044D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 3 page(s) / 88K

Publishing Venue

IBM

Related People

Dimitri, KE: AUTHOR [+3]

Abstract

Disclosed is a scheme which provides a method of establishing and identifying a track reference without the use of a specialized address mark (AM) field. The scheme replaces AM by using phase-locked loop (PLL) control signals and disk controller logic decision.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Scheme for Establishing a Track Reference After the Completion of
a Seek Operation On a Storage Device

      Disclosed is a scheme which provides a method of
establishing and identifying a track reference without the use of a
specialized address mark (AM) field.  The scheme replaces AM by using
phase-locked loop (PLL) control signals and disk controller logic
decision.

      The AM field is used in today's disk format architecture to
establish a reference point on a track, particularly after a seek
operation to the track is completed.  When an Address Mark field is
detected, the PLL is set to high gain in order to establish frequency
lock within the synchronization field in preparation for reading the
mark detect (MD) field for bit alignment.

      The scheme uses the PLL locking signal to identify the
synchronization field and hence arm the decision logic in the
controller for comparing the MD and sector ID to establish a track
reference.  The PLL acts as a burst detector, since it quickly locks
to a synchronization field pattern essentially doing the same job as
the address mark.

      The two modes of PLL operation are the unoriented and the
oriented searches.  The unoriented search mode occurs at the end of a
seek operation  and no new track reference has yet been established;
whereas, the oriented search mode occurs during the normal read
operation and after a track reference is established.

      Once a track seek command is issued, the PLL is in the squelch
and high gain modes.  When the...