The authors describe the single-chip i860 CPU, a 64-bit, RISC (reduced-instruction-set-computer)-based microprocessor that executes parallel instructions using mainframe and supercomputer architectural concepts. They designed the 1,000,000-transistor, 10-mm*15-mm processor for balanced integer, floating-point, and graphics performance. They discuss the RISC core, memory management, floating-point unit, graphics, bus interface, software support, and interfacing to a DRAM system.