PA-RISC
Encyclopedia
PA-RISC is an instruction set architecture (ISA) developed by Hewlett-Packard
Hewlett-Packard
Hewlett-Packard Company or HP is an American multinational information technology corporation headquartered in Palo Alto, California, USA that provides products, technologies, softwares, solutions and services to consumers, small- and medium-sized businesses and large enterprises, including...

. As the name implies, it is a reduced instruction set computer
Reduced instruction set computer
Reduced instruction set computing, or RISC , is a CPU design strategy based on the insight that simplified instructions can provide higher performance if this simplicity enables much faster execution of each instruction. A computer based on this strategy 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
HP 3000
The HP 3000 series is a family of minicomputers released by Hewlett-Packard in 1973. It was designed to be the first minicomputer delivered with a full featured operating system with time-sharing. The first models were withdrawn from the market until speed improvements could be made. It ultimately...

 and HP 9000 Model 840
HP 9000
HP 9000 is the name for a line of workstation and server computer systems produced by the Hewlett-Packard Company . The native operating system for almost all HP 9000 systems is HP-UX, a derivative of Unix. The HP 9000 brand was introduced in 1984 to encompass several existing technical...

 computers were launched featuring the first implementation, the TS1.

PA-RISC has been succeeded by the Itanium
Itanium
Itanium is a family of 64-bit Intel microprocessors that implement the Intel Itanium architecture . Intel markets the processors for enterprise servers and high-performance computing systems...

 (originally IA-64) ISA jointly developed by HP and Intel
Intel Corporation
Intel Corporation is an American multinational semiconductor chip maker corporation headquartered in Santa Clara, California, United States and the world's largest semiconductor chip maker, based on revenue. It is the inventor of the x86 series of microprocessors, the processors found in most...

. HP stopped selling PA-RISC-based HP 9000 systems at the end of 2008 but will support servers running PA-RISC chips until 2013.

History

In the late 1980s HP was building four series of computers, all based on CISC
Complex instruction set computer
A complex instruction set computer , is a computer where single instructions can execute several low-level operations and/or are capable of multi-step operations or addressing modes within single instructions...

 CPUs. One line was the IBM PC compatible
IBM PC compatible
IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. Such computers used to be referred to as PC clones, or IBM clones since they almost exactly duplicated all the significant features of the PC architecture, facilitated by various manufacturers' ability to...

 Intel i286 based Vectra Series started 1986. All others were non-Intel systems. One of them was the HP Series 300 of Motorola 68000
Motorola 68000
The Motorola 68000 is a 16/32-bit CISC microprocessor core designed and marketed by Freescale Semiconductor...

-based workstation
Workstation
A workstation is a high-end microcomputer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems...

s, another Series 200 line of technical workstations based on a custom silicon on sapphire
Silicon on sapphire
Silicon on sapphire is a hetero-epitaxial process for integrated circuit manufacturing that consists of a thin layer of silicon grown on a sapphire wafer. SOS is part of the Silicon on Insulator family of CMOS technologies...

 (SOS) chip design, the SOS based 16-bit HP 3000
HP 3000
The HP 3000 series is a family of minicomputers released by Hewlett-Packard in 1973. It was designed to be the first minicomputer delivered with a full featured operating system with time-sharing. The first models were withdrawn from the market until speed improvements could be made. It ultimately...

 classic series and finally the HP 9000 Series 500 minicomputer
Minicomputer
A minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems and the smallest single-user systems...

s, 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.

Precision Architecture was introduced in 1986. It had thirty-two 32-bit integer registers and sixteen 64-bit floating-point registers. The number of floating-point registers was doubled in the 1.1 version to 32 once it became apparent that 16 were inadequate and restricted performance. The architects included Allen Baum, Hans Jeans, Michael J. Mahon, Ruby Bei-Loh Lee, Russel Kao, Steve Muchnick, Terrence C. Miller, David Fotland, and William S. Worley.

The first implementation was the TS1, a central processing unit built from discrete transistor-transistor logic
Transistor-transistor logic
Transistor–transistor logic is a class of digital circuits built from bipolar junction transistors and resistors. It is called transistor–transistor logic because both the logic gating function and the amplifying function are performed by transistors .TTL is notable for being a widespread...

 (74F TTL) devices. Later implementations were multi-chip VLSI designs fabricated in NMOS processes (NS1 and NS2) and CMOS (CS1 and PCX). They were first used in a new series of HP 3000
HP 3000
The HP 3000 series is a family of minicomputers released by Hewlett-Packard in 1973. It was designed to be the first minicomputer delivered with a full featured operating system with time-sharing. The first models were withdrawn from the market until speed improvements could be made. It ultimately...

 machines in the late 1980s – the 930 and 950, commonly known at the time as Spectrum systems, the name given to them in the development labs. These machines ran MPE/iX. The HP 9000
HP 9000
HP 9000 is the name for a line of workstation and server computer systems produced by the Hewlett-Packard Company . The native operating system for almost all HP 9000 systems is HP-UX, a derivative of Unix. The HP 9000 brand was introduced in 1984 to encompass several existing technical...

 machines were soon upgraded with the PA-RISC processor as well, running the HP-UX
HP-UX
HP-UX is Hewlett-Packard's proprietary implementation of the Unix operating system, based on UNIX System V and first released in 1984...

 version of UNIX
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...

.

Other operating systems ported to the PA-RISC architecture include Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

, OpenBSD
OpenBSD
OpenBSD is a Unix-like computer operating system descended from Berkeley Software Distribution , a Unix derivative developed at the University of California, Berkeley. It was forked from NetBSD by project leader Theo de Raadt in late 1995...

, NetBSD
NetBSD
NetBSD is a freely available open source version of the Berkeley Software Distribution Unix operating system. It was the second open source BSD descendant to be formally released, after 386BSD, and continues to be actively developed. The NetBSD project is primarily focused on high quality design,...

 and NEXTSTEP
NEXTSTEP
NeXTSTEP was the object-oriented, multitasking operating system developed by NeXT Computer to run on its range of proprietary workstation computers, such as the NeXTcube...

.

An interesting aspect of the PA-RISC line is that most of its generations have no Level 2 cache
CPU cache
A CPU cache is a cache used by the central processing unit of a computer to reduce the average time to access memory. The cache is a smaller, faster memory which stores copies of the data from the most frequently used main memory locations...

. Instead large Level 1 caches are used, formerly as separate chips connected by a bus, and now integrated on-chip. Only the PA-7100LC and PA-7300LC had L2 caches. Another innovation of the PA-RISC was the addition of vectorized instructions (SIMD
SIMD
Single instruction, multiple data , is a class of parallel computers in Flynn's taxonomy. It describes computers with multiple processing elements that perform the same operation on multiple data simultaneously...

) in the form of MAX
Multimedia Acceleration eXtensions
The Multimedia Acceleration eXtensions or MAX are instruction set extensions to the Hewlett-Packard PA-RISC instruction set architecture ....

, which were first introduced on the PA-7100LC.

The ISA was extended in 1996 to 64-bits, with this revision named PA-RISC 2.0. PA-RISC 2.0 also added fused multiply–add instructions, which help certain floating-point intensive algorithms, and the MAX-2
Multimedia Acceleration eXtensions
The Multimedia Acceleration eXtensions or MAX are instruction set extensions to the Hewlett-Packard PA-RISC instruction set architecture ....

 SIMD extension, which provides instructions for accelerating multimedia applications. The first PA-RISC 2.0 implementation was the PA-8000
PA-8000
The PA-8000 , code-named Onyx, is a microprocessor developed and fabricated by Hewlett-Packard that implemented the PA-RISC 2.0 instruction set architecture . It was a completely new design with no circuitry derived from previous PA-RISC microprocessors...

, which was introduced in January 1996.

CPU specifications

Model   Marketing nameYearFrequency [MHz]Memory Bus [MB/s]Process [µm]Transistors [millions]Die size [mm²]Power [W]Dcache [kB]Icache [kB]L2 cache [MB]ISANotes
TS-1 ? 1986 8 ? ? ? ? ? 1.0
CS-1 ? 1987 8 ? 1.6 0.164 72.93 1 0.25 1.0
NS-1 ? 1987 25/30 ? 1.5 0.144 70.56 ? ? ? 1.0
NS-2 ? 1989 27.5/30 ? 1.5 0.183 196 27 512 512 1.0
PCX ? 1990 ? ? ? ? ? ? ? ? ? 1.0
PCX-S PA-7000 1991 66 ? 1.0 0.58 201.6 ? 256 256 1.1a
PCX-T PA-7100
PA-7100
The PA-7100 is a microprocessor developed by Hewlett-Packard that implemented the PA-RISC 1.1 instruction set architecture . It is also known as the PCX-T and by its code-name Thunderbird. It was introduced in early 1992 and was the first PA-RISC microprocessor to integrate the floating-point unit...

 
1992 33–100 ? 0.8 0.85 196 ? 2048 1024 1.1b
PCX-T PA-7150  1994 125 ? 0.8 0.85 196 ? 2048 1024 1.1b
PCX-T' PA-7200
PA-7200
The PA-7200 , code-named Thunderbird, is a microprocessor that implements the PA-RISC 1.1 instruction set architecture developed by Hewlett-Packard . It was introduced in early 1995, debuting in systems from HP...

 
1994 120 960 0.55 1.26 210 30 1024 2048 1.1c
PCX-L PA-7100LC
PA-7100LC
The PA-7100LC is a microprocessor that implements the PA-RISC 1.1 instruction set architecture developed by Hewlett-Packard . It is also known as the PCX-L, and by its code-name, Hummingbird. It was designed as a low-cost microprocessor for low-end systems. The first systems to feature the...

 
1994 60–100 ? 0.75 0.9 201.6 7–11 1 2 1.1d
PCX-L2 PA-7300LC  1996 132–180 ? 0.5 9.2 260.1 ? 64 64 0–8 1.1e
PCX-U PA-8000
PA-8000
The PA-8000 , code-named Onyx, is a microprocessor developed and fabricated by Hewlett-Packard that implemented the PA-RISC 2.0 instruction set architecture . It was a completely new design with no circuitry derived from previous PA-RISC microprocessors...

 
1996 160–180 960 0.5 3.8 337.68 ? 1024 1024 2.0
PCX-U+ PA-8200  1997 200–240 960 0.5 3.8 337.68 ? 2048 2048 2.0
PCX-W PA-8500  1998 300–440 1920 0.25 140 467 ? 1024 512 2.0
PCX-W+ PA-8600  2000 360–550 1920 0.25 140 467 ? 1024 512 2.0
PCX-W2 PA-8700(+) 2001 625–875 1920 0.18 186 304 <7.1@1.5 V 1536 768 2.0
Mako PA-8800  2003 800–1000 6400 0.13 300 361 ? 768/core 768/core 32 2.0
Shortfin PA-8900  2005 800–1100 6400 0.13 ? ? ? 768/core 768/core 64 2.0

See also

  • Hombre chipset
    Hombre chipset
    The Hombre chipset was to be a chipset for use in game machine hardware. However, because of Commodore International's bankruptcy, the Hombre chipset was never released.-History:...

     - A PA-7150-based chipset with a complete multimedia system for Commodore
    Commodore International
    Commodore is the commonly used name for Commodore Business Machines , the U.S.-based home computer manufacturer and electronics manufacturer headquartered in West Chester, Pennsylvania, which also housed Commodore's corporate parent company, Commodore International Limited...

    -Amiga
    Amiga
    The Amiga is a family of personal computers that was sold by Commodore in the 1980s and 1990s. The first model was launched in 1985 as a high-end home computer and became popular for its graphical, audio and multi-tasking abilities...


External links

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