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RISC Acronym for reduced instruction set computer. A computer based on a processor or processors designed to execute a small number of simple register-based instructions extremely fast, preferably one instruction for every cycle of the system clock. (Hence RISC also stands for reduced instruction set complexity.) RISC processors employ pipelining and on-chip instruction and data cache memory among other techniques. Various RISC architectures have been developed by manufacturers, including Hewlett-Packard's HP-PA (precision architecture), ARM RISC processors from Advanced RISC Machines Ltd, Digital Equipment's Alpha AXP, Sun Microsystem's SPARC (scalable processor architecture), MIPS processors from MIPS Technologies Inc., and the PowerPC produced by a partnership between IBM, Apple, and Motorola.