This paper summarizes a survey of concurrent-processing computer systems, particularly their descriptive differences and performance. The motivation is the high data processing rates required by ever-larger applications of infrared sensors and radar for data accumula-tion and the speed constraints of technology. The scope of the application and the technological limitations have caused consideration of alternative computer systems architectures for signal processing. In support of this, a survey was done of installations which are built and functioning, first to assess the architecture's application to signal processing, and second, to understand the difficulties inherent in developing an operational concurrent-processing computer system. The surveyed systems include C.mmp, Cm*, PLURIBUS, S-1, ILLIAC IV, STARAN, PEPE, CDC *100, TIASC, CRI - CR1, and the fault tolerant systems JPL-STAR and SRI-Sift. Some systems have been excluded from this paper because they either are not completed to an operational stage or are classified. In this investigation of system architectural issues for signal processing applications, it became evident that no effective systems characterizations for concurrent processors exist. Furthermore, performance measures for these systems are awkward and poorly related to the characterizations. The performance mea-sures thus need refinement. A descriptor is proposed which contains the elements of data flow, control and reliability and to which the performance measures can be properly related.