Browse Prior Art Database

Controlling the Maximum Synchronous Data Transfer Rate of a Small Computer System Interface And Command Timeout Values

IP.com Disclosure Number: IPCOM000102562D
Original Publication Date: 1990-Dec-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

McNeill, AB: AUTHOR [+2]

Abstract

This article describes a technique which provides software control to alter operating characteristics of a small computer system interface (SCSI) bus.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 66% of the total text.

Controlling the Maximum Synchronous Data Transfer Rate of a Small Computer System Interface And Command Timeout Values

       This article describes a technique which provides
software control to alter operating characteristics of a small
computer system interface (SCSI) bus.

      The technique disclosed herein allows a personal computer (PC)
system software to optimize the SCSI data transfer rate and SCSI
device command timeout values depending on the particular SCSI
subsystem configuration. The maximum values will be chosen based on
the number of devices attached, type of devices attached, the SCSI
bus cable length, and whether devices are connected to the external
SCSI connector.  This technique will allow system software to slow
down the SCSI data transfer rate as required for some system
configurations for reliability, data integrity, and/or to meet
electromagnetic compatibility (EMC) requirements.  The maximum
command time duration allowed by the SCSI adapters will be set by
system software as required when very slow device operations are
anticipated, for example, when a tape device is performing a rewind
function or a hard disk is being formatted.

      The Immediate Feature Control command for SCSI adapters allows
the system initialization and device driver software to control the
SCSI bus synchronous data transfer rate and command timeout as
needed.  At system power-on time, the system initialization code will
determine the appropriate values to...