A system having a processor, a printed circuit board, and an adapter board, coupled to the processor through the printed circuit board. The adapter board provides a first signal having a first state when the adapter board is in a proper operating condition and a second state when the adapter board is...http://www.google.com.au/patents/US7711869?utm_source=gb-gplus-sharePatent US7711869 - Method for communicating plural signals generated at a source to a remote destination through a single wire
