Browse Prior Art Database

Small Computer System Interface Bus Isolation for a Small Computer System Interface Controller Adapter

IP.com Disclosure Number: IPCOM000113996D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Andresen, ME: AUTHOR

Abstract

Disclosed is a SCSI controller adapter within a computer system having an external connector, through which external devices may be attached, an internal connector, through which internal devices may be attached, and an isolation buffer between controller circuits and the internal connector.

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

Small Computer System Interface Bus Isolation for a Small Computer
System Interface Controller Adapter

      Disclosed is a SCSI controller adapter within a computer system
having an external connector, through which external devices may be
attached, an internal connector, through which internal devices may
be attached, and an isolation buffer between controller circuits and
the internal connector.

      The Figure is a schematic view of an adapter card 10 having
SCSI controller circuits 12 connected, by means of SCSI bus, to an
external connector 16 and an internal connector 18.  External
connector 16 is used to extend the SCSI bus to various external
devices (not shown), while internal connector 18 is used extend the
SCSI bus to various internal devices (also not shown), within a
computer system.  The SCSI bus includes  an ACK line 20, on which the
ACK signal is sent from controller circuits 12 to the various
devices, and an REQ line 22, on which the REQ signal is sent from the
various devices to controller circuits 12.  The ACK and REQ lines are
connected to an isolation buffer 24, consisting of a driver for ACK
and a receiver for REQ, between controller circuits 12 and internal
connector 18.  The remaining lines 25 of the SCSI bus are connected
directly to both connectors 16 and 18.  A control register 26 enables
and disables isolation buffer 24 under the control of system
software.  Termination circuits 28 are the same for all
configurations, and standa...