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Automatic Log Out Analysis

IP.com Disclosure Number: IPCOM000091532D
Original Publication Date: 1968-Mar-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Tomas, WM: AUTHOR [+2]

Abstract

Intermittent failures in the Central Processing Unit CPU of a data processing machine can be diagnosed through the use of multiple log-outs of the CPU status. Implementation of a multiple log-out technique is especially realized in a data processing machine which contains circuitry which, upon indication of an error, forces a log-out of the CPU status and then attempts to re-execute the instruction during which an error was detected.

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Automatic Log Out Analysis

Intermittent failures in the Central Processing Unit CPU of a data processing machine can be diagnosed through the use of multiple log-outs of the CPU status. Implementation of a multiple log-out technique is especially realized in a data processing machine which contains circuitry which, upon indication of an error, forces a log-out of the CPU status and then attempts to re-execute the instruction during which an error was detected.

Detection of a processing error causes a Machine Check Interrupt MCI. At this time, a log-out of the CPU status is gated to a buffer. A machine cycle pointer, such as the contents of a Read-Only Storage Address Register ROAR, and the contents of the Instruction Address Register IAR are gated to associated backup registers ROAR-BU and IAR-BU. Trigger T1 is then turned on.

As part of the retry procedure, the data processing machine is first set to a previous known correct state. It then attempts to reexecute the program from that point. If the condition which causes the MCI is intermittent in nature and the retry is successful, there is an output signal from the Compare circuit. Such signal occurs when the data processing machine reaches the state at which the MCI had occurs. The output of the Compare circuit is utilized to force a new CPU log-out and to gate both the new log-out and the previous log-out an Exclusive-OR EOR. The output of the latter indicates any differences in CPU status at the time that the...