Fault tolerant networking architecture

A fault-tolerant system for sharing multiple peripherals between a plurality of computers, comprising:

• a plurality of peripherals each being attached to each of a plurality of computers;
• a semaphore box attached to each of said plurality of computers having a plurality of input ports, a redundant set of semaphores and a plurality of output ports;
• each of said plurality of input ports being attached in a dedicated fashion to one of said plurality of computers through a communications channel;
• and
• each of said plurality of output ports being attached in a dedicated fashion to one of said plurality of computers through said channel and including voting circuitry to select among a majority of said redundant set of semaphores.

A method for preventing the indefinite reservation of one of a plurality of shared peripherals by one of a plurality of computers using dedicated heartbeat semaphores assigned to each of the plurality of computers, comprising the steps of:

• a.) sending reservation commands to a central location to reserve one of the plurality of peripherals by each of the plurality of computers;
• b.) servicing the reservation commands such that each of the plurality of computers is an accessing computer for the following substeps:
• b1.) setting a reservation semaphore to reserve the peripheral for the accessing computer;
• b2.) setting the heartbeat semaphores assigned to the accessing computer to indicate a communication from the accessing computer has occurred;
• b3.) returning the values of a plurality of the heartbeat semaphores to the accessing computer;
• b4.) clearing the plurality of heartbeat semaphores;
• c.) counting a time interval that each of the values of the plurality of heartbeat semaphores remains cleared;
• d.) clearing any reservation semaphores that were set by one of the plurality of computers if the interval is greater than a predetermined amount.