Browse Prior Art Database

Small Computer System Interface Identifier Change Circuit

IP.com Disclosure Number: IPCOM000104548D
Original Publication Date: 1993-May-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Aruga, N: AUTHOR

Abstract

Disclosed is a circuit to change SCSI (Small Computer System Interface) device IDs electrically. without affecting other SCSI devices. The SCSI ID also means SCSI address. In general, it is made by mechanical switches or jumpers. This disclosure circuit makes the installation easier.

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Small Computer System Interface Identifier Change Circuit

      Disclosed is a circuit to change SCSI (Small Computer System
Interface) device IDs electrically.  without affecting other SCSI
devices.  The SCSI ID also means SCSI address.  In general, it is
made by mechanical switches or jumpers.  This disclosure circuit
makes the installation easier.

      Fig. 1 shows the circuits.  The SCSI target device has usually
three jumper pins.  These three signals are cabled to the output
register-2.  The "-RST" signal on the SCSI bus and "-ID SET" signal
are ORed to the "-RST-Targ" signal.  The "-RST-Targ" signal is
connected to "-RST" signal line of the target device.  Other SCSI
signals are connected on the SCSI bus as usual.  These output
registers and circuits are mounted on the system planar with the SCSI
initiator.  The reset condition does not affect the other external
SCSI devices.

      The following steps shows the ID change procedure.

      Step 1.  Set the target SCSI ID on the output register-2.

      Step 2.  Assert "-ID SET" signal through the output register-1
for a minimum of reset hold
        time defined by the SCSI standard.

      Step 3.  The target re-read its address setting.

      Step 4.  The initiator on the system planar issues appropriate
commands along with the
        SCSI standard, such as TEST UNIT READY.