1. A self testing data processing system comprising: a communications bus having a plurality of connection slots for bidirectional communication between said slots; at least one nonintelligent data processing circuit, each nonintelligent data processing circuit connected to one of said slots and having a test memory means connected to and readable from said communications bus, said test memory means having a diagnostic program, written in an intermediate level interpretable test language, stored therein for testing said nonintelligent data processing circuit; and at least one intelligent data processing circuit connected to said communications bus and having an interpreter program and a testing means, said interpreter program for interpreting said intermediate level interpretable test language, and said testing means, including data processing means for executing programs stored in memory, for testing said at least one nonintelligent data processing circuit via said communications bus by recall, interpretation and execution of said test program stored in said test memory means.