Electrical pulse counters – pulse dividers – or shift registers: c – Systems – Identifying or correcting improper counter operation
Patent
1983-11-02
1986-01-21
Heyman, John S.
Electrical pulse counters, pulse dividers, or shift registers: c
Systems
Identifying or correcting improper counter operation
377 39, 3281291, H03K 2130
Patent
active
045661111
ABSTRACT:
A watchdog timer for monitoring the operation of a computer monitors if the period of a writing signal (W.sub.T) generated by each execution of an instruction of a program is within the predetermined duration. The present watchdog timer comprises a register (2) for storing predetermined DATA upon receipt of the writing signal (W.sub.T), a counter (4) which is incremented by a clock pulse (.phi.), a comparator (3) for providing coincidence output signal when content of the counter reaches said predetermined DATA in the register (2), a first flip-flop (F.sub.1) for storing said coincidence output signal for one period of said clock pulse (.phi.), a second flip-flop (F.sub.2) for storing said coincidence output signal upon receipt of said clock pulse (.phi.), a third flip-flop (F.sub.3) for storing output of said second flip-flop (F.sub.2) upon receipt of said clock pulse (.phi.), an AND circuit (G.sub.1) for providing logical product of reverse output (Q.sub.1) of said first flip-flop (F.sub.1) and said writing signal (W.sub.T), and an OR circuit (G.sub. 2) for receiving an output of said third flip-flop (F.sub.3) and an output of said AND circuit (G.sub.1) and producing an alarm signal NG which indicates an error of a computer to be monitored.
REFERENCES:
patent: 4079234 (1978-03-01), Kashio
patent: 4161649 (1979-07-01), Klos et al.
patent: 4189635 (1980-02-01), Sheller
Heyman John S.
Novack Martin
Oki Electric Industry Co.
LandOfFree
Watchdog timer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Watchdog timer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Watchdog timer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2301674