Browse Prior Art Database

Microcode Overrun Checking

IP.com Disclosure Number: IPCOM000043240D
Original Publication Date: 1984-Aug-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Bigo, F: AUTHOR [+3]

Abstract

In those realtime microcoded applications that run within a microprocessor not including any internal timer, interrupt requests to the microprocessor represent the only available timing information. If a program overruns, an interrupt request could be missed, thereby breaking the sequence of events which times the processed application. This article describes a technique for detecting such an overrun and for indicating an alarm condition to the system. According to the proposed technique, an interrupt latch is associated with each interrupt source. At power-on reset, all of the interrupt latches are reset to an inactive condition.

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Microcode Overrun Checking

In those realtime microcoded applications that run within a microprocessor not including any internal timer, interrupt requests to the microprocessor represent the only available timing information. If a program overruns, an interrupt request could be missed, thereby breaking the sequence of events which times the processed application. This article describes a technique for detecting such an overrun and for indicating an alarm condition to the system. According to the proposed technique, an interrupt latch is associated with each interrupt source. At power-on reset, all of the interrupt latches are reset to an inactive condition. When an interrupt is requested to the microprocessor, the interrupt latch to which the request is associated is set to an active condition and remains in this condition until the interrupt request is served by the microprocessor which then resets the interrupt latch. If an interrupt is requested by a source while the associated interrupt latch is in an active condition, thereby indicating that an interrupt request has been missed by the microprocessor, an alarm indicator latch is set to an active condition. This alarm latch active condition, directly or when read by a diagnostic program, indicates an abnormal condition to the system.

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