Reliability Aspects of the Variable Instruction Computer

This paper is intended to show how the unique features of the Variable Instruction Computer (VIC) make it valuable for applications requiring high reliability. By careful choice of components, use of error-checking circuits, and selected application of redundant hardware, the basic unextended reliability of the VIC is comparable with the state-of-the-art. This is verified by a standard MIL-HDBK-217 type of analysis. The variable instruction technique is briefly described by use of a block diagram. The method for extending reliability by use of variable instructions is explained and an example is given. The concept of algorithm change to achieve controlled graceful degradation is discussed. An analysis of a typical application of this technique is given and extensions of the variable instruction concept to more advanced reliability requirements are discussed.