Browse Prior Art Database

Small Computer System Interface Single Ended to Differential Adapter

IP.com Disclosure Number: IPCOM000106493D
Original Publication Date: 1993-Nov-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 4 page(s) / 95K

Publishing Venue

IBM

Related People

Buckland, PA: AUTHOR [+3]

Abstract

A SCSI (Small Computer System Interface) single-ended to differential converter is implemented on a small card that is attached to a single- ended SCSI device such as a disk drive. Both an 8 bit and a 16 bit design were implemented, Figs. 1, 2.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Small Computer System Interface Single Ended to Differential Adapter

      A SCSI (Small Computer System Interface) single-ended to
differential converter is implemented on a small card that is
attached to a single- ended SCSI device such as a disk drive.  Both
an 8 bit and a 16 bit design were implemented, Figs. 1, 2.

      Contained on the adapter are differential to single-ended
transceivers (1) and control logic (2) for enabling and disabling the
differential drivers.  The control logic is implemented on a single
chip which is common to the 8 and 16 bit designs.  The connections
between the converter board and the single-ended SCSI device consist
of:

   - the single-ended SCSI connector (3)
   - the SCSI ID (identification) jumper block (4)

A differential connector (5) on the convertor is used to make the
connection to the SCSI differential bus.

      The converter card is attached directly to the device making
the SCSI single-ended bus only a few centimeters long.  The 4ma
receiver output from the transceivers is sufficient to drive this
short bus, eliminating the need for the 48ma drivers required to
drive a standard single-ended bus, which can be up to 6 meters in
length.

      A novel part of the design is the logic that controls the
enabling of the differential drivers.  In a conventional differential
SCSI design where the differential transceivers are integrated into
the device, these control signals are provided by the SCSI protocol
chip.  For the case of a separate converter card, these signals must
be synthesized by sampling the single-ended and differential signals.

      Since the convertor is dedicated to one single-ended device,
the SCSI ID of which is kn...