SPARC (Scalable Processor Architecture) is a 32- and 64-bit microprocessor architecture from Sun Microsystems that is based on reduced instruction set computing (RISC). SPARC has become a widely-used architecture for hardware used with UNIX-based operating systems, including Sun's own Solaris systems. Sun has made SPARC an open architecture that is available for licensing to microprocessor manufacturers. In its most recent brand name, UltraSPARC, microprocessors can be built for PC boards (using either Peripheral Component Interconnect or ATX) as well as for SPARC's original workstation market. As evidence of SPARC's scalability, Sun says that its UltraSPARC III will be designed to allow up to 1,000 processors to work together.
Although the idea of RISC is sometimes attributed to IBM's John Cocke, Sun Microsystems was the first to provide a microprocessor that exploited it for the workstation market and it's possible to say that, together with UNIX, SPARC created the workstation market. (IBM has since used it in its successful RISC System/6000 line of workstations.) Since its inception in 1987, the SPARC architecture has included these ideas:
- Reduce the number of instructions that the processor has to perform to a minimal number (one idea of RISC is that a complex instruction in a conventional computer can be reduced to a series of simpler operations, requiring a simpler architecture and a more compact microprocessor)
- Reduce the number of types of memory addresses that the processor needs to handle
- Put as little processor operation as possible in microcode, which requires clock speed-consuming time to access
- Provide language compilers that compile programs that are optimized for a SPARC microprocessor by being arranged in an order that the processor can handle more efficiently