Backup control system (BUCS)

Claim 2

In a computer system (10) having a plurality of identical processors (12) and controlling a device (24), a method of providing control over the device comprising: installing identical primary software in a portion (18) of memory (16) associated with each processor (12), said primary software directing the operation of the processors to control the device during normal operation; installing backup software, dissimilar from the primary software, in an isolated portion (20) of memory (16) associated with at least one of the processors (12), said backup software capable of directing the operation of the processor(s) to control the device of in the event of a sensed event; sensing for a fault event occurring in the primary software affecting all processors; sensing for a fault event occurring in the primary software affecting a majority of the processors (12); sensing for an externally initiated event represented by a backup software transfer command signal; providing a nonmaskable interrupt request in response to one of said sensed events; completing whatever instruction is being executed in the primary software when the nonmaskable interrupt request is provided, and then acknowledging the nonmaskable interrupt request; and disabling the primary software and executing the backup software in response to the nonmaskable interrupt request so as to maintain control over the device with the backup software associated with the at least one processor.

Claim 3

A method according to claim 1, comprising jam-transferring to the isolated portion of memory in response to the sensed fault.

Claim 4

A method according to claim 1 wherein the backup software is simpler than the primary software.

Claim 5

In a computer system (10) having at least two identical processors (12) and controlling a device (24), a method of providing control over the device comprising: installing identical primary software in a portion (18) of memory (16) associated with each processor (12), said primary software directing the operation of the processors to control the device during normal operation; installing backup software, dissimilar from the primary software, in an isolated portion (20) of memory (16) associated with at least one of the processors (12), said backup software capable of directing the operation of the processor(s) to control the device in the event of a sensed fault in the primary software affecting all processors; enabling a nonmaskable interrupt request circuit; sensing the fault in the primary software affecting all processors; providing a nonmaskable interrupt request in response to the sensed fault; completing whatever instruction is being executed in the primary software when the nonmaskable interrupt request is provided, and then acknowledging the nonmaskable interrupt request; and disabling the primary software and executing the backup software in response to the nonmaskable interrupt request so as to maintain control over the device with the backup software associated with the at least one processor.

Claim 6

In a computer system (10) having at least two identical processors (12) and controlling a device (24), a method of providing control over the device comprising: installing identical primary software in a portion (18) of memory (16) associated with each processor (12), said primary software directing the operation of the processors to control the device during normal operation; installing backup software, dissimilar from the primary software, in an isolated portion (20) of memory (16) associated with at least one of the processors (12), said backup software capable of directing the operation of the processor(s) to control the device in the event of a sensed fault in the primary software affecting all processors; enabling a nonmaskable interrupt request circuit; sensing the fault in the primary software affecting all processors; providing a nonmaskable interrupt request in response to the sensed fault; completing whatever instruction is being executed in the primary software when the nonmaskable interrupt request is provided, and then acknowledging the nonmaskable interrupt request; and disabling the primary software and executing the backup software in response to the nonmaskable interrupt request so as to maintain control over the device with the backup software associated with the at least one processor.

Claim 7

In a computer system (10) having a plurality of identical processors (12) and controlling a device (24), a method of providing control over the device comprising: installing identical primary software in a portion (18) of memory (16) associated with each processor (12), said primary software directing the operation of the processors to control the device during normal operation: installing backup software, dissimilar from the primary software, in an isolated portion (20) of memory (16) associated with at least one of the processors (12), said backup software capable of directing the operation of the processors(s) to control the device in the event of a sensed fault in the primary software affecting a majority of the processors; sensing a first to occur fault in the primary software affecting any one or more of the processors; providing a transfer enable signal for a selected period after sensing said fault in said one or more of the processors; sensing said fault in the primary software affecting a majority of the processors and providing a transfer signal for so long as said fault persists; providing a nonmaskable interrupt request in response to the sensed fault only if said transfer signal occurs concurrently with said enable signal; completing whatever instruction is being executed in the primary software when the nonmaskable interrupt request is provided, and then acknowledging the nonmaskable interrupt request; and disabling the primary software and executing the backup software in response to the nonmaskable interrupt request so as to maintain control over the device with the backup software associated with the at least one processor.

Claim 8

In a computer system (10) having a plurality of identical processors (12) and controlling a device (24), a method of providing control over the device comprising: installing identical primary software in a portion (18) of memory (16) associated with each processor (12), said primary software directing the operation of the processors to control the device during normal operation: installing backup software, dissimilar from the primary software, in an isolated portion (20) of memory (16) associated with at least one of the processors (12), said backup software capable of directing the operation of the processors(s) to control the device in the event of a sensed fault in the primary software affecting a majority of the processors; sensing a first to occur fault in the primary software affecting any one or more of the processors; providing a transfer enable signal for a selected period after sensing said fault in said one or more of the processors; sensing said fault in the primary software affecting a majority of the processors and providing a transfer signal for so long as said fault persists; providing a nonmaskable interrupt request in response to the sensed fault only if said transfer signal occurs concurrently with said enable signal; completing whatever instruction is being executed in the primary software when the nonmaskable interrupt request is provided, and then acknowledging the nonmaskable interrupt request; and disabling the primary software and executing the backup software in response to the nonmaskable interrupt request so as to maintain control over the device with the backup software associated with the at least one processor.