PA-RISC

PA-RISC is an instruction set architecture (ISA) developed by Hewlett-Packard. As the name implies, it is a reduced instruction set computer (RISC) architecture, where the PA stands for Precision Architecture. The design is also referred to as HP/PA for Hewlett Packard Precision Architecture.

The architecture was introduced on 26 February 1986, when the HP 3000 Series 930 and HP 9000 Model 840 computers were launched featuring the first implementation, the TS1.

PA-RISC has been succeeded by the Itanium (originally IA-64) ISA, jointly developed by HP and Intel. HP stopped selling PA-RISC-based HP 9000 systems at the end of 2008 but supported servers running PA-RISC chips until 2013.

History

In the late 1980s, HP was building four series of computers, all based on CISC CPUs. One line was the IBM PC compatible Intel i286-based Vectra Series, started in 1986. All others were non-Intel systems. One of them was the HP Series 300 of Motorola 68000-based workstations, another Series 200 line of technical workstations based on a custom silicon on sapphire (SOS) chip design, the SOS based 16-bit HP 3000 classic series, and finally the HP 9000 Series 500 minicomputers, based on their own (16 and 32-bit) FOCUS microprocessor. HP planned to use PA-RISC to move all of their non-PC compatible machines to a single RISC CPU family.

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.