Design considerations in a multiprocessor computer for continuous system simulation

The current importance of computer simulation of dynamic systems is well-known. Such simulation is useful in system analysis, design, and testing, as well as in the training of human operators. Whenever a computer simulation involves interaction with actual system hardware (including humans) the computation must by definition take place in real-time; i.e., the computer must solve the simulation equations at the same speed with which the actual dynamic system operates. Real-time simulation of dynamic systems plays an important role in many areas of technology, including aerospace, process control, automotive, and other applications. In the simulation of flight vehicles such as aircraft, helicopters, and missiles the computational requirements associated with real-time simulation can become especially severe due to the complexity of the equations to be solved and the high frequencies present in the dynamic behavior of the solutions. In the early 1950's, when real-time simulation of flight vehicles began to be achieved on a widespread basis, only analog computers possessed the necessary dynamic capability to accomplish the simulation. Over the ensuing two decades, as digital computers have increased dramatically in speed and computing power, more and more of the realtime simulation of flight vehicles (and other dynamic systems) has been taken over by digital computers. For example, today even general purpose digital minicomputers have the capability of real-time simulation of many aircraft. However, there continue to be many flight-vehicle systems which currently are impossible or uneconomical to simulate adequately in real-time with existing general-purpose digital computers, e.g., small high-performanc~ missiles, high performance aircraft which include flight-control system dynamics, helicopters, and jet engines. In many of these cases the simulation is being performed successfully with hybrid (i.e., combined analog/digital) computing systems. However, because of the potential advantages which all-digital simulation can have over hybrid simulation, e.g.,