Browse Prior Art Database

SCSI Device Auto-Sensing for On-Board SCSI Interface Sub-System

IP.com Disclosure Number: IPCOM000111406D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Fukushima, A: AUTHOR [+2]

Abstract

This article describes an SCSI device auto-sensing scheme to disable an on-board SCSI interface sub-system when no SCSI device is attached to the sub-system in order to release system resources that are allocated to the SCSI interface sub-system.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 70% of the total text.

SCSI Device Auto-Sensing for On-Board SCSI Interface Sub-System

      This article describes an SCSI device auto-sensing scheme to
disable an on-board SCSI interface sub-system when no SCSI device is
attached to the sub-system in order to release system resources that
are allocated to the SCSI interface sub-system.

      A SCSI interface adapter, when installed into a Personal
Computer, has bad effects on system resources when any SCSI device is
not attached to it.

1.  Adapter ROM, RAM on SCSI interface sub-system occupies reserved
    memory area of Personal Computer system so that the resources can
    not be allocated to other memory-resident Device Drivers or
    adapters.

2.  Other adapters can not use I/O address, interrupt level and DMA
    channel that are allocated to the SCSI interface sub-system.

3.  SCSI interface adapter ROM contains execution codes for Power-On
    Self Test (POST).  The POST codes always run at any power on even
    if no SCSI device is attached.

4.  If the disabling circuit is implemented with hardware jumper or
    DIP switch, it may cause setting error by a customer.

      In case the SCSI interface sub-system is provided as an
adapter, the problems above are easily resolved by removing the
adapter from the Personal Computer.  But if the SCSI interface
sub-system is imbedded as on-board of the Personal Computer, they can
not be avoided.  With this invention, the circuit detects whether any
SCSI dev...