Duplex processor arrangement for a switching system
First Claim
1. A method of controlling a duplex processor arrangement comprising a pair of computing circuits each comprising a processor portion and a control portion, the processor portion including a microprocessor and an associated instruction cache memory and the control portion comprising a maintenance controller, a match circuit, and an interrupt controller, the maintenance controller, match circuit and interrupt controller of each computing circuit being responsively interconnected to each other and connected to their respective processor portion as well as to respective mate circuits in the other of the computing circuits, the control portion also including an instruction counter for cyclically counting to a predetermined number instructions executed by its respective microprocessor, each of the computing circuits being driven from a respective independent clock circuit, the method comprising the steps of,each of the instruction counters counting the instructions executed by its associated microprocessor,the instruction counter to first reach the predetermined number generating a flag signal, and, the maintenance control associated with that instruction counter responding to the flag signal by inhibiting execution of further instructions by its associated microprocessor until the instruction counter of the other computing circuit has also reached the predetermined number whereby a rendezvous between the computing circuits has occurred, the inhibiting step being achieved by the maintenance controller responsive to the flag signal generating an instruction cache disable signal that causes a cache-miss cycle to occur at the processor instruction that is coincident with the flag signal and for preventing completion of the cache-miss cycle until the match circuits of the computing circuits and the maintenance controller associated with the instruction counter to first reach the predetermined number have determined that the computing circuits are at the same point in the software processing stream.
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Accused Products
Abstract
The invention provides a duplex processor arrangement wherein the processors are only pseudo-synchronized to each other. Each processor is provided with its own independent clock circuit and the two clock circuits operate at the same nominal frequency. A circuit means is provided for periodically forcing a rendezvous between processors whereat a controller circuit ensures that the processors have processed the same information since the last rendezvous. Each processor comprises a match circuit including memory means connected to store address/data information related to instructions performed by the processors. Each match circuit compares the information from the processors and generates an alarm signal upon a mismatch.
38 Citations
8 Claims
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1. A method of controlling a duplex processor arrangement comprising a pair of computing circuits each comprising a processor portion and a control portion, the processor portion including a microprocessor and an associated instruction cache memory and the control portion comprising a maintenance controller, a match circuit, and an interrupt controller, the maintenance controller, match circuit and interrupt controller of each computing circuit being responsively interconnected to each other and connected to their respective processor portion as well as to respective mate circuits in the other of the computing circuits, the control portion also including an instruction counter for cyclically counting to a predetermined number instructions executed by its respective microprocessor, each of the computing circuits being driven from a respective independent clock circuit, the method comprising the steps of,
each of the instruction counters counting the instructions executed by its associated microprocessor, the instruction counter to first reach the predetermined number generating a flag signal, and, the maintenance control associated with that instruction counter responding to the flag signal by inhibiting execution of further instructions by its associated microprocessor until the instruction counter of the other computing circuit has also reached the predetermined number whereby a rendezvous between the computing circuits has occurred, the inhibiting step being achieved by the maintenance controller responsive to the flag signal generating an instruction cache disable signal that causes a cache-miss cycle to occur at the processor instruction that is coincident with the flag signal and for preventing completion of the cache-miss cycle until the match circuits of the computing circuits and the maintenance controller associated with the instruction counter to first reach the predetermined number have determined that the computing circuits are at the same point in the software processing stream.
Specification