Operating experience with a multiple-processor system for data acquisition and reduction in nuclear physics

Abstract

A multiprocessor system based on commercially available VMEbus components has been developed for the acquisition and reduction of event-mode data in nuclear structure physics experiments. The system contains seven 68000 CPU’s and 14MB of memory. A simple operating system handles data transfer and task allocation, and a compiler for a specially designed event analysis language produces code for the processors. Design considerations are discussed for the hardware and software, with emphasis on the differences in requirements between nuclear and high-energy physics applications. The system has been in operation for four years at the University of Pennsylvania Tandem Accelerator Laboratory. Computation rates several times that of a MicroVAX II have been achieved at a fraction of the cost. A recent improvement to the system has been the addition of WORM optical disks which allow the processing of gigabyte data sets without operator intervention.