The Huge Microphone Array(HMA) project started in February 1994 to design, construct, and test a real-time 512-microphone array system and to develop algorithms for use on it. Analysis of known algorithms showed that signal-processing performance of over 6 Gigaflops would be required; at the same time, there was a need for ''portability'', i.e., fitting into a small van. These tradeoffs and many others have led to a unique design in both hardware and software. This paper presents the design and its justifications. Performance data for a few important algorithms relative to usage of processing-capability, response latency, and difficulty of programming are discussed.