RISC (disambiguation)

RISC may refer to:

See also

Reduced instruction set computing

Reduced instruction set computing, or RISC (pronounced 'risk'), is a CPU design strategy based on the insight that a simplified instruction set (as opposed to a complex set) provides higher performance when combined with a microprocessor architecture capable of executing those instructions using fewer microprocessor cycles per instruction. A computer based on this strategy is a reduced instruction set computer, also called RISC. The opposing architecture is called complex instruction set computing, i.e. CISC.

Various suggestions have been made regarding a precise definition of RISC, but the general concept is that of a system that uses a small, highly optimized set of instructions, rather than a more versatile set of instructions often found in other types of architectures. Another common trait is that RISC systems use the load/store architecture, where memory is normally accessed only through specific instructions, rather than accessed as part of other instructions like add.

IBM System p

The System p, formerly known as RS/6000, was IBM's RISC/UNIX-based server and workstation product line.

In April 2008, IBM announced a rebranding of the System p and its unification with the System i platform. The resulting product line is called IBM Power Systems.

History

It was originally a line of workstations and servers called RS/6000. The server line was then renamed to the eServer pSeries in 2000 as part of its e-Server branding initiative. With the advent of the POWER5 processor in 2004, the family was rebranded the eServer p5. With the global move of the server and storage brands to the System brand with the Systems Agenda, the family was renamed yet again to System p5 in 2005. The System p5 now encompasses the IBM OpenPower product line. With the introduction of POWER6 processor models, the new models were released under the System p brand, dropping the p5 designation.

Processors

Whereas RS/6000 used a mix of early POWER and PowerPC processors, when pSeries came along this had evolved into RS64-III and POWER3 across the board—POWER3 for its excellent floating-point performance and RS64 for its scalability, throughput, and integer performance.