Apparatus for indicating abnormal program execution in a process controlling computer operating in real time on different priority levels

Claim 1

Apparatus for use with a process controlling computer having a central processing unit and operating in real time on different priority levels which consist of a number of program sectors to indicate to such computer that it is spending greater than a predetermined time at least on one of the priority levels, said apparatus comprising: a first multiposition register means wherein each position is assigned to a different one of the priority levels, said register means being adapted to receive signals from the central processing unit for establishing predetermined states in the positions to indicate which priority level is operative in the central processing unit, a clock pulse means for generating clock pulses, a plurality of first pulse counters, each of said first pulse counters being associated with a different one of the priority levels and having at least one output for emitting a signal when the accumulated pulse count reaches a predetermined value, logic means for connecting said clock pulse means and said first multiposition register means to said plurality of first pulse counters so that each of said first pulse counters counts clock pulses during its associated priority level, a multiposition control register means wherein each position is associated with a different priority level, said multiposition control register means being adapted to emit indicator signals to the central processing unit in accordance with which ones of its positions are in a particular state, each of said positions having an input for receiving a signal and in response thereto assuming said particular state, and connecting means for connecting the outputs of each of said first pulse counters associated with the different priority levels to the positions of said control register means associated with the corresponding priority levels.