Adaptive computers

Abstract

In this paper we shall consider some design aspects of a computer which has two new modes of operation, which we call adaptive. One new mode of operation is the computer's ability to carry out useful computation even when component failures are present. This operation may be achieved at the expense of computational rate or accuracy. The ability to achieve this mode of operation is called graceful degradation, and its implementation differs from the redundancy techniques normally used to increase the reliability of a computer. The second mode of operation consists of the computer's ability to automatically increase the throughput at the expense of computation time and accuracy. Both hardware and software procedures for accomplishing these goals will be outlined. The results of this work are applicable to the design of those space-borne computers which need be operational for long periods of time, such as a year or two. Normally, the effective life of a piece of equipment is measured in terms of its mean time between failure (MTBF). However, for the computer system to be described, we are more interested in how long the system can carry out its overall functional goal, rather than the MTBF of its hardware.