Browse Prior Art Database

Hardware Determination of Active Interrupt Sources

IP.com Disclosure Number: IPCOM000104593D
Original Publication Date: 1993-May-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Guttmann, JE: AUTHOR

Abstract

A method for using hardware to determine active interrupt sources in microprocessor-based systems is disclosed.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 79% of the total text.

Hardware Determination of Active Interrupt Sources

      A method for using hardware to determine active interrupt
sources in microprocessor-based systems is disclosed.

      In microprocessor-based systems, it is common to have hardware
logic generate a signal which "interrupts" the microprocessor from
executing one task to perform another.  Since the hardware may detect
several conditions which could cause an interrupt, the microprocessor
must be able to determine which interrupts are active.  Described is
a method for making that determination within the hardware itself.

      The figure shows a diagram of the hardware logic involved.
Various conditions which can cause an interrupt to the microprocessor
set a designated bit in the Interrupt Status Register.  Here, for
example, eight conditions labeled "A" through "H" set a bit in the
Interrupt Status Register whenever that condition is true.  (For
simplicity, only the logic for interrupt condition "A" is completely
shown.)

      To allow the microprocessor to "mask" or disable unwanted
interrupts, each interrupt condition also has a companion bit in the
Interrupt Enable Register.  In order for the Microprocessor Interrupt
signal to become active, both the Interrupt Status bit and the
corresponding Interrupt Enable bit must be true.

      The Active Interrupt Register gives the microprocessor
immediate access to the hardware's internal combination of
corresponding Interrupt Status and Interrup...