Browse Prior Art Database

Optical Drive Detection of a Library

IP.com Disclosure Number: IPCOM000108925D
Original Publication Date: 1992-Jul-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Goodman, BG: AUTHOR

Abstract

An optical drive that is used for both a stand-alone device and a library device needs to know which environment it is in for purposes of Error Recovery Procedures (ERPs) and timings. This article describes one approach.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 57% of the total text.

Optical Drive Detection of a Library

       An optical drive that is used for both a stand-alone
device and a library device needs to know which environment it is in
for purposes of Error Recovery Procedures (ERPs) and timings.  This
article describes one approach.

      It is desirable for an optical drive to know whether it is in a
stand-alone or library application.  This allows the drive to use the
most appropriate ERPs, the best cartridge insert delays, etc.

      The common approach to this problem uses a host-to-drive
command (a SCSI command in our case) to tell the drive which
application it should support.  This technique requires microcode
support of a special command by the host machine and the drive.  This
method is not failsafe because any host machine could issue the
required SCSI command to switch the drive into a library mode.

      This article suggests an alternate approach in which the drive
used the library eject as a means of detecting in which application
it is being used.  The optical library uses a library interface cable
that attaches to each drive in the library.  One of the logic wires
on this cable is a library eject line that the library uses to eject
a cartridge from the drive.  It should be noted that this line is the
only means that the library uses to eject cartridges.  Upon power-up,
the library moves the picker mechanism in front of each drive and
issues an eject command to ensure that the drives do not have a
c...