Browse Prior Art Database

Small Computer System Interface Wrapping Driver

IP.com Disclosure Number: IPCOM000104103D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Becker, DE: AUTHOR [+4]

Abstract

Described is a Small Computer System Interface (SCSI) bus driver that adds isolation and diagnostic options to SCSI interfaces.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Small Computer System Interface Wrapping Driver

      Described is a Small Computer System Interface (SCSI) bus
driver that adds isolation and diagnostic options to SCSI interfaces.

      An SCSI Differential driver implementation is detailed in the
figure.  By controlling one additional signal, a SCSI controller can
determine, on a bit basis, the functionality of the SCSI bus drivers.
When the WRAP signal is active (high), the driver section of the
driver/receiver both drives and receives.  The signal A is the VLSI
SCSI bidi data bit and is set to the receive mode internal to the
VLSI chip when the WRAP signal is activated.  The signal DE/-RE
determines whether the driver is enabled and drives the logical one
forced by WRAP or is disabled and allows the respective SCSI bus bit
to be biased to a logical zero by the SCSI bus termination.  The
receiver portion is always receiving when WRAP is active (assuming
the chip enable line, CE is active).  The microprocessor controlling
the SCSI VLSI interface chip can thus wrap signals out to the SCSI
bus and test that the respective driver/receiver is functioning.