Browse Prior Art Database

Read Channel Reconfiguration "On the Fly" to Read the Control Track Data On Optical Media

IP.com Disclosure Number: IPCOM000121077D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 93K

Publishing Venue

IBM

Related People

Tipton, L: AUTHOR

Abstract

Optical media control track data can be read quickest by changing the read channel parameters, on a per sector basis, to account for all compatible media. This enhances drive performance by reducing the control data read time.

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

Read Channel Reconfiguration "On the Fly" to Read the Control Track
Data On Optical Media

      Optical media control track data can be read quickest by
changing the read channel parameters, on a per sector basis, to
account for all compatible media.  This enhances drive performance by
reducing the control data read time.

      There are a variety of optical disks in the marketplace.  Most,
if not all types, contain vital disk characteristic data in an area
known as the control track zone.  The data is used to optimize the
optical disk drive to the optical media installed.  On an ANSI
standard 90 mm optical disk there are two zones, each with sixteen
tracks of control data.  Each track contains 25 sectors of control
data.  Each sector of control data is replicated throughout both
control track zones.

      When an optical disk cartridge is installed in a drive, it is
unknown what type of media it is.  The drive must go through a
sequence of self configurations in an attempt to read the control
track data.  After reading the data, the drive can optimize itself
for the media installed.

      Normally a design point is set that defines optical media and
drive compatibility.  For example, a design point may be DROM, MO or
mixed MO/ROM media and the control information will always be
embossed by the media manufacturer.  Disk base line reflectivities
are different between all DROM and all MO or mixed media.  This
requires adjustments to the read channel to prevent saturation while
reading the control track zones.

      After a cartridge is installed, the spindle is turned on,
allowed to achieve final velocity and the tracking and focus servo
calibrations are executed.  These calibrations give the drive enough
capability to read the control data, if the media is compatible with
the drive.  The actuator seeks and spirals (for spiral media) to the
first sector of the first track of one of the control track zones.
The read channel is set up to read ROM data on a DROM disk (the
projection is that DROM media will be used most...