Browse Prior Art Database

Multiple ID SCSI Bus Controller

IP.com Disclosure Number: IPCOM000103883D
Original Publication Date: 1993-Feb-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Becker, DE: AUTHOR [+4]

Abstract

SCSI architecture limits the attachment of 8 devices/logical unit numbers (LUNs) under a single control unit located at one ID on the SCSI Bus. This is a problem if more devices/LUNs require attachment and the expense of another SCSI Bus controller is not acceptable. Also, as devices get smaller and smaller, the controller hardware ends up taking more and more space so the ability to reduce the number of controllers needed to attach these devices becomes a significant advantage.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 54% of the total text.

Multiple ID SCSI Bus Controller

      SCSI architecture limits the attachment of 8 devices/logical
unit numbers (LUNs) under a single control unit located at one ID on
the SCSI Bus.  This is a problem if more devices/LUNs require
attachment and the expense of another SCSI Bus controller is not
acceptable.  Also, as devices get smaller and smaller, the controller
hardware ends up taking more and more space so the ability to reduce
the number of controllers needed to attach these devices becomes a
significant advantage.

      A method of providing an SCSI Bus controller with the mechanism
to respond to selections at one or more IDs, thereby allowing
attachment of more than 8 devices/LUNs per controller, is disclosed.
It also gives the controller the ability to respond to no selections
at any ID until ready to handle a selection.

      When attaching devices/LUNs to a SCSI Bus through a controller,
it may be desirable that the controller respond to selections at more
than one ID.  Also, the controller should not respond to a selection
at any ID until the system attached to the controller is ready to
process commands that will be received during the selection.  Both of
these situations can be handled with the use of a writable register
which contains the IDs to which the controller should respond.

The characteristics of this register are:

o   One bit position is available for each of the possible IDs on the
    SCSI Bus.  This could be implemented for an...