SIGMA-1 is the most significant computer prototype based on a dataflow architecture, aiming to outperform conventional von Neumann computers. This large-scale dataflow computer, for scientific and technological computations, is developed at the Electrotechnical Laboratory, Ministry of International Trade and Industry. This paper overviews the system architecture of the SIGMA-1, and discusses its ... [Show full abstract] system performance. The architectural issues in dataflow computing machines and the design decisions made in the SIGMA-1 project in achieving 170 MFLOPS performance are presented. The history of the SIGMA-1 project is also briefly outlined.