Diagnostic system

A diagnostic system for a multi-processor computer comprising, in combination:

• a controller bus;
• a plurality of diagnostic system controllers each coupled to said controller bus, each diagnostic system controller having a countdown timer settable to a unique value different from that of all other diagnostic system controllers and actuated at substantially the same time, the diagnostic system controller in which said countdown timer first goes to zero becomes the master diagnostic system controller;
• each diagnostic system controller being responsive to unique signals on said control bus from said master diagnostic system controller to place reply signals to said master diagnostic system controller on said controller bus;
• a communication bus coupled to each said diagnostic system controller;
• a plurality of processor units coupled to each said communication bus, each processor unit including diagnostic hardware actuated by a first unique signal on said communication bus to perform diagnostic tests on the hardware in said processor unit and to place the diagnostic test results to said communicator bus in response to the receipt of a second unique signal;
• each diagnostic system controller including means to produce said first and said second unique signals on said controller bus;
• and
• said master diagnostic system controller being operative to actuate said means to produce said first and said second unique signals on each said controller bus.