Method and apparatus for microcode loading in a multi-nodal network exhibiting distributed control

A distributed data processing system comprising:

• plural nodes, each node containing a data processor;
• data link means interconnecting neighboring nodes so as to enable communications therebetween, certain said plural nodes coupled via plural data link means through an intermediate node or nodes;
• non-volatile storage means in each node for storing a copy of base microcode, said base microcode enabling a data processor in a node to manifest partial operational capabilities, including program loading functions and a communication function with neighbor nodes;
• memory means in at least one node, but less than all said plural nodes, for storing functional microcode that enables said at least one node to fully accomplish assigned data processing tasks;
• and
• load means in each of said plural nodes in combination with the data processor and base microcode residing in each said node, for determining if a copy of said functional microcode resides in said node and, if not, said load means issuing a request only to neighbor nodes connected by one data link, and not to any node interconnected thereto via an intermediate node, to download said functional microcode, and to continue issuing said request to download said functional microcode until one of said neighbor nodes responds by downloading said functional microcode or until a further control function is enabled, said load means further responsive to a request from a neighbor node connected by a direct link to download said functional microcode if a copy of said microcode is present in said node and to otherwise be non-responsive upon receipt of said request, and to be responsive to a subsequent said request only if said functional microcode exists in memory of the node.

A method for initial program load in nodes of a distributed data processing system, each node having plural neighbor nodes, a node connected to a neighbor node via a direct link, certain of said nodes coupled to other nodes via intermediate nodes, each node performing a method comprising the steps of:

• responding to a power-up signal to load base microcode from resident read only memory in said node;
• determining whether functional microcode is present in non-volatile memory in said node and, if yes, loading said functional microcode into random access memory to prepare said node for full data processing action, and if no, issuing a request to neighbor nodes connected by a direct link for a download of said functional microcode;
• reissuing said request to download said functional microcode only to neighbor nodes connected by a direct link if no download of functional microcode is received within a predetermined time period;
• and
• responding to a request from a neighbor node connected by a direct link to download said functional microcode if a copy of said microcode is present in said node and to otherwise be non-responsive upon receipt of said request, and to be responsive to a subsequent said request only if said functional microcode exists in memory of the node.