Investigation and simulation of a self-repairing digital computer

A system for incorporating self-repair capabilities into a digital computer is presented. This self-repairing system is based upon the replacement of failed circuitry via a switching mechanism activated as a result of a failure detection, classification, and diagnostic procedure. The self-repairing computer constructed of state-of-the-art circuitry has a variable organization as determined by the content of the state register which controls a switching mechanism. To permit repair of the multiplicity of failures which totally disable the computer, a master machine has been associated with the computer to aid in all phases of the self-repair process. This added unit or the computer itself may control the content of the state register. For a sample design, it was determined that the self-repair mechanism including the master machine increased the size of the central processing unit by only approximately 30 percent. The mean life between catastrophic failures of the sample self-repairing computer is found to be up to four times that of a standard design computer of equivalent capability. Since the self-repairing computer requires the simultaneous operation of a master machine and the computer itself, it was necessary to develop a simulation program for use in an iterative design of the self-repairing computer mechanism. This simulation tool demonstrated the self-repair features, permitted evaluation of the self-repair process, and yielded knowledge about the operational characteristics of self-repairing digital computers.