The SPARC is a RISC processor developed by Sun. The design was more or less released to the world, and it is currently produced by around a dozen different companies too numerous to even bother mentioning. It is worth noting that even computers made by Sun typically sport SPARCs made by other companies. A couple different OSes run on SPARC based machines, including Solaris, SunOS, and Linux. Some of the newer SPARC models are called UltraSPARCs.