In order for the successful operation of a test routine to guarantee that a computing system has no faulty components, the test conditions imposed by the routine should be devised at the level of the components themselves, rather than at the level of programmed orders. Therefore, it seems that the proper approach to writing test or maintenance routines is by way of the logical diagrams of the system, and not the list of machine orders. This is the only way in which all conditions of operation of each logical function can be uniquely and completely defined and all logical components within each logical function can be made to perform the task to which they are assigned. Orders can then be programmed to present all conditions, and further orders can be programmed to detect improper performance of the logical functions, thereby producing a minimum program which tests and detects failure in each logical component, in the system.

2. Background and Definitions A method of producing such a test routine was developed and applied to the Central Processor of the Datamatic 1000 system. The logical functions in the Datamatic 1000 were implemented by tubes and diodes. The functions are in the form of buffer-gate-buffer and were originally represented by logical statements. Since almost any system is originally represented by logical statements, the method described here could be applied equally well to another system.