Browse Prior Art Database

Shortening Interrupt Processing Times

IP.com Disclosure Number: IPCOM000122120D
Original Publication Date: 1991-Nov-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 1 page(s) / 57K

Publishing Venue

IBM

Related People

Ruzek, GL: AUTHOR [+2]

Abstract

Disclosed is method for using part of a programmed interrupt value in SCRIPTS* code as a hash index into a pointer table. This pointer then directs the SCSI (Small Computer System Interface) device driver to the device structure representing the interrupt target device.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 55% of the total text.

Shortening Interrupt Processing Times

      Disclosed is method for using part of a programmed
interrupt value in SCRIPTS* code as a hash index into a pointer
table. This pointer then directs the SCSI (Small Computer System
Interface) device driver to the device structure representing the
interrupt target device.

      SCRIPTS is a language that controls the execution of the NCR
53C700 family of SCSI controller chips.  The SCRIPTS allows dynamic
setting of interrupt values by the device driver at run-time.
Interrupts reside within a set of SCRIPTS code generated for each
SCSI target associated with the SCSI initiator.  These interrupts,
along with other portions of the SCRIPTS, are customized to fit the
SCSI commands passed from the device driver to the target device.

      Two current methods of SCRIPTS programming are: use of distinct
interrupt value for every device or use of boundary checking for a
set of generic interrupts.  The use of distinct interrupts requires
the interrupt handler to match the interrupt value to the only device
that can be associated with that interrupt.  This lookup table will
be very large in order to handle the number of possible devices and
the number of possible interrupts associated for each device.  In
addition to the time taken to access a large table, much of the
reserved table space is wasted on non-existing devices and their
special interrupts never used.  With the generic interrupt method,
the interrupt handler dete...