Browse Prior Art Database

Automatic Small Computer System Interface Termination

IP.com Disclosure Number: IPCOM000115074D
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Peterson, JC: AUTHOR [+2]

Abstract

Disclosed is a method for actively terminating a Small Computer System Interface (SCSI) port on a desktop PowerPC* system when no external device is attached.

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This is the abbreviated version, containing approximately 100% of the total text.

Automatic Small Computer System Interface Termination

      Disclosed is a method for actively terminating a Small Computer
System Interface (SCSI) port on a desktop PowerPC* system when no
external device is attached.

      While active termination for SCSI II is recommended, it is
required that no unterminated stub of greater than approximately 3.9
inches is allowed.  This has typically meant that on external
connections, an external termination block was required.

      Desktop PowerPC systems, however, use an active terminator with
a disable.  This disable is then tied to one of the ground pins on
the external connector.  Whenever no external device is present, the
DISABLE_ signal is high (inactive), enabling the termination.
Whenever an external device is installed, the ground is completed
through the device, therefore disabling the terminator.  See the
Figure for an illustration of this concept.
  *  Trademark of IBM Corp.