FAULT PROTECTION FLIP-FLOP

摘要

The disclosure relates to the use of a logic latch such as a flip flop to provide additional protection against the destruction of data located in microprocessor system support circuits. The microprocessor can affect both the latch and the support circuits but cannot affect the support circuits without first affecting the logic latch. The logic latch enables the support circuits to be affected by the microprocessor. Thus, the microprocessor must correctly execute a sequence of code in the proper order to affect the support circuits. The microprocessor must first arm, i.e., set the latch, and then affect the support circuits. The proper sequence will not occur during common failure modes of the microprocessor. Consequently, the microprocessor will not be able to erroneously affect the support circuits during common failure modes of the microprocessor. This inability then provides the support circuits protection from a failing microprocessor. Connecting communication paths can be used by remote intelligent devices to interrogate the support circuits. Remote intelligent devices can then determine the electronic state of the support circuits. Diagnostic and maintainability functions are enhanced by remote intelligent interrogations. This protection is particularly applicable to critical stored information that should not be erroneously written over by the microprocessor.