Programmable Active Memories: the Coming of Age

Programmable Active Memories (PAM) are a novel form of universal hardware co-processor. Based on Field-Programmable Gate Array (FPGA) technology, a PAM is a virtual machine, controlled by a standard microprocessor, which can be dynamically configured into a large number of application-specific circuits. PAMs offer a new mixture of hardware performance and software versatility. We review the important architectural features of PAMs, through the example of DECPeRLe-1, an experimental device built in 1992. We analyze the virtual computing power of such co-processors, from now into the predictable future. PAM programming is presented, in contrast to classical gate-array and full custom circuit design. Our emphasis is on large, code-generated synchronous systems descriptions; no compromise is made with regard to the performance of the target circuits. We exhibit a dozen applications where PAM technology proves superior, both in performance and cost, to every other existing technology, including supercomputers, massively parallel machines, and conventional custom hardware. The fields covered include computer arithmetic, cryptography, error correction, image analysis, stereo vision, video compression, sound synthesis, high-energy physics, thermodynamics and astronomy.