The Huge Microphone Array (HMA) is a collaborative effort between Brown University and Rutgers University that started in February 1994 to design, construct, debug, and test a real-time 512-microphone array system and to develop algorithms for use on it. Analysis of known algorithms made it clear 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, that also set an upper limit to the power required. It was essential that the array be able to be used in both large and small acoustic environments. These tradeoffs and many others have led to a unique design in both hardware and software. The hardware uses 128 fast, floating-point DSP microprocessors and is designed so that data flow is independent of data processing. This leads to an unusually simple software environment. This paper presents the full design and its justifications. Performance for a few important algorithms relative to usage of processing-capability, response latency, and difficulty of programming is discussed. [Work supported by NSF Grant MIP-9314625.]