PR rating
Encyclopedia
The PR system was developed by AMD in the mid-1990s as a method of comparing their x86 processors to those of rival Intel.
processor was as fast as a Pentium running at 75 MHz. The designation "P75" was added to the chip to denote this.
The letters PR stood for "Performance Rating", but many people mistakenly thought it stood for "Pentium Rating", as the PR was often used to measure performance against Intel's Pentium processor.
Later that year, Cyrix
also adopted the PR system for its 6x86 and 6x86MX line of processors. These processors were capable of handling business applications under Microsoft
Windows
faster than Pentiums of the same clock speed, so Cyrix PR-rated the chips one or two Pentium speed grades higher than clock speed. AMD did likewise with some versions of their K5
processor, but abandoned the system when it introduced the K6
.
) performance, far below that of a Pentium. Many experts argued that this made the PR-rated chips poor choices for games, any kind of streaming video, or encoding MP3
music.
Others took the opposing view that the great majority of users at that time were performing integer-intensive tasks like word-processing, spreadsheeting and web browsing, and the substantially lower cost of the PR-rated processors allowed the user to afford a higher-spec part in any case . The question remains controversial to this day. With the demise of the Cyrix MII (a renamed 6x86MX) from the market in 1999, the PR system appeared to be dead, but AMD revived it in 2001 with the introduction of its Athlon XP
line of processors.
microprocessor. Although the processor was inferior to its predecessor, the Pentium III
, on a clock-for-clock basis, Intel designed the processor to be capable of reaching much higher clock speeds than the Pentium III. Using the fact that the raw Gigahertz (GHz) speed of the Pentium 4 was faster than AMD's Athlon XP microprocessor, Intel advertised the Pentium 4 using clock speed to distinguish between the performances of their different processor models. This marketing was effective for Intel as they had used this method for since the introduction of the Pentium, because consumers could compare quantitative clock speeds much, much more easily than comparing qualitative microprocessor features.
The continuation of this practice, despite lower performance per clock, led consumers to conclude that AMD's Athlon XP processors, because they had much slower clock speeds than Intel's Pentium 4 processors, were inferior to Intel's Pentium 4 microprocessors. In reality, on a clock-for-clock basis, the Athlon XP microprocessor was superior to the Pentium 4 on a number of benchmarks. An Athlon XP with a 2 GHz clock would easily outperform a 2 GHz Pentium 4 on most benchmarks.
manufacturers conspicuously showed the PR number of the microprocessor in the motherboards' POST
and not include the processors' clock speeds anywhere except within the BIOS
.
The use of the convention with these processors (which are rated against AMD's earlier Thunderbird-based Athlon
processors) is less criticized, as the Athlon XP is a capable performer in both integer and FPU operations, and manages to outperform an Intel Pentium 4 at a PR equalling the Pentium 4's clock speed. The Athlon XP (as well as the Athlon 64) PR scheme is not intended to be anything more than a comparison to the same family of processors, and not a direct comparison to Intel or any other company's processor speeds (in raw MHz), despite what sceptics may believe.
, using a P6 microarchitecture descendant in Pentium M
CPUs and beyond, and using multiple processing cores
in its processors.
Because of the philosophy change, Intel now faces the challenge of making consumers compare its processors based on the PR system rather than raw clock speed, ironically a problem which Intel created itself.
Some analysts regard the PR scheme (and a raw MHz/ GHz rating) as nothing more than a marketing tactic, rather than as a useful measure of CPU performance. Many professionals or interested amateurs now consult extensive benchmark
tests to determine system performance on various applications.
Branding
The first use of the PR system was in 1996, when AMD used it to assert that their AMD 5x86AMD 5x86
The Am5x86 processor is an x86-compatible CPU introduced in 1995 by AMD for use in 486-class computer systems. It was one of the fastest, and most universally-compatible upgrade paths for users of 486 systems....
processor was as fast as a Pentium running at 75 MHz. The designation "P75" was added to the chip to denote this.
The letters PR stood for "Performance Rating", but many people mistakenly thought it stood for "Pentium Rating", as the PR was often used to measure performance against Intel's Pentium processor.
Later that year, Cyrix
Cyrix
Cyrix Corporation was a microprocessor developer that was founded in 1988 in Richardson, Texas as a specialist supplier of high-performance math coprocessors for 286 and 386 microprocessors. The company was founded by former Texas Instruments staff members and had a long but troubled relationship...
also adopted the PR system for its 6x86 and 6x86MX line of processors. These processors were capable of handling business applications under Microsoft
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
faster than Pentiums of the same clock speed, so Cyrix PR-rated the chips one or two Pentium speed grades higher than clock speed. AMD did likewise with some versions of their K5
AMD K5
The K5 was AMD's first x86 processor to be developed entirely in-house. Introduced in March 1996, its primary competition was Intel's Pentium microprocessor. The K5 was an ambitious design, closer to a Pentium Pro than a Pentium regarding technical solutions and internal architecture...
processor, but abandoned the system when it introduced the K6
AMD K6
The K6 microprocessor was launched by AMD in 1997. The main advantage of this particular microprocessor is that it was designed to fit into existing desktop designs for Pentium branded CPUs. It was marketed as a product which could perform as well as its Intel Pentium II equivalent but at a...
.
Criticism
The PR system drew heavy criticism. The ratings were based on a limited set of benchmark suites which measured only integer performance, which the K5 and the 6x86 in particular excelled at. Both processors had weak floating-point (FPUFloating point unit
A floating-point unit is a part of a computer system specially designed to carry out operations on floating point numbers. Typical operations are addition, subtraction, multiplication, division, and square root...
) performance, far below that of a Pentium. Many experts argued that this made the PR-rated chips poor choices for games, any kind of streaming video, or encoding MP3
MP3
MPEG-1 or MPEG-2 Audio Layer III, more commonly referred to as MP3, is a patented digital audio encoding format using a form of lossy data compression...
music.
Others took the opposing view that the great majority of users at that time were performing integer-intensive tasks like word-processing, spreadsheeting and web browsing, and the substantially lower cost of the PR-rated processors allowed the user to afford a higher-spec part in any case . The question remains controversial to this day. With the demise of the Cyrix MII (a renamed 6x86MX) from the market in 1999, the PR system appeared to be dead, but AMD revived it in 2001 with the introduction of its Athlon XP
Athlon
Athlon is the brand name applied to a series of x86-compatible microprocessors designed and manufactured by Advanced Micro Devices . The original Athlon was the first seventh-generation x86 processor and, in a first, retained the initial performance lead it had over Intel's competing processors...
line of processors.
Pentium 4 competition
In 2000, Intel debuted its Pentium 4Pentium 4
Pentium 4 was a line of single-core desktop and laptop central processing units , introduced by Intel on November 20, 2000 and shipped through August 8, 2008. They had a 7th-generation x86 microarchitecture, called NetBurst, which was the company's first all-new design since the introduction of the...
microprocessor. Although the processor was inferior to its predecessor, the Pentium III
Pentium III
The Pentium III brand refers to Intel's 32-bit x86 desktop and mobile microprocessors based on the sixth-generation P6 microarchitecture introduced on February 26, 1999. The brand's initial processors were very similar to the earlier Pentium II-branded microprocessors...
, on a clock-for-clock basis, Intel designed the processor to be capable of reaching much higher clock speeds than the Pentium III. Using the fact that the raw Gigahertz (GHz) speed of the Pentium 4 was faster than AMD's Athlon XP microprocessor, Intel advertised the Pentium 4 using clock speed to distinguish between the performances of their different processor models. This marketing was effective for Intel as they had used this method for since the introduction of the Pentium, because consumers could compare quantitative clock speeds much, much more easily than comparing qualitative microprocessor features.
The continuation of this practice, despite lower performance per clock, led consumers to conclude that AMD's Athlon XP processors, because they had much slower clock speeds than Intel's Pentium 4 processors, were inferior to Intel's Pentium 4 microprocessors. In reality, on a clock-for-clock basis, the Athlon XP microprocessor was superior to the Pentium 4 on a number of benchmarks. An Athlon XP with a 2 GHz clock would easily outperform a 2 GHz Pentium 4 on most benchmarks.
Revived for Athlon XP
In reaction to the consumers' misconception, AMD reinstated the PR to compare their Athlon XP microprocessors. AMD made sure to advertise the PR number of its microprocessors rather than their raw clock speeds believing that customers would compare the PR of AMD's processors to the clock speed of Intel's processors. The PR number was originally believed to show the clock speed (in megahertz) of an equivalent Pentium 4 processor, but this was never confirmed by AMD. As part of its marketing, AMD even made sure that motherboardMotherboard
In personal computers, a motherboard is the central printed circuit board in many modern computers and holds many of the crucial components of the system, providing connectors for other peripherals. The motherboard is sometimes alternatively known as the mainboard, system board, or, on Apple...
manufacturers conspicuously showed the PR number of the microprocessor in the motherboards' POST
Power-on self-test
Power-On Self-Test refers to routines run immediately after power is applied, by nearly all electronic devices. Perhaps the most widely-known usage pertains to computing devices...
and not include the processors' clock speeds anywhere except within the BIOS
BIOS
In IBM PC compatible computers, the basic input/output system , also known as the System BIOS or ROM BIOS , is a de facto standard defining a firmware interface....
.
The use of the convention with these processors (which are rated against AMD's earlier Thunderbird-based Athlon
Athlon
Athlon is the brand name applied to a series of x86-compatible microprocessors designed and manufactured by Advanced Micro Devices . The original Athlon was the first seventh-generation x86 processor and, in a first, retained the initial performance lead it had over Intel's competing processors...
processors) is less criticized, as the Athlon XP is a capable performer in both integer and FPU operations, and manages to outperform an Intel Pentium 4 at a PR equalling the Pentium 4's clock speed. The Athlon XP (as well as the Athlon 64) PR scheme is not intended to be anything more than a comparison to the same family of processors, and not a direct comparison to Intel or any other company's processor speeds (in raw MHz), despite what sceptics may believe.
End of the MHz race
Between 2001 and 2003, Intel and AMD made few changes to the designs of their processors. Most performance increases were created by raising the processor's clock speed rather than improving the microprocessor's core. Around mid 2004, Intel encountered serious problems in increasing their Pentium 4's clock speed beyond 3.4 GHz because of the enormous amount of heat generated by the already hot Prescott core processor when working at higher clock speeds. In response, Intel started exploring ways to improve the performance of its microprocessors in ways other than raising the clock speeds of the processors such as increasing the sizes of the processors' cachesCPU 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...
, using a P6 microarchitecture descendant in Pentium M
Pentium M
The Pentium M brand refers to a family of mobile single-core x86 microprocessors introduced in March 2003 , and forming a part of the Intel Carmel notebook platform under the then new Centrino brand...
CPUs and beyond, and using multiple processing cores
Multi-core (computing)
A multi-core processor is a single computing component with two or more independent actual processors , which are the units that read and execute program instructions...
in its processors.
Because of the philosophy change, Intel now faces the challenge of making consumers compare its processors based on the PR system rather than raw clock speed, ironically a problem which Intel created itself.
Some analysts regard the PR scheme (and a raw MHz/ GHz rating) as nothing more than a marketing tactic, rather than as a useful measure of CPU performance. Many professionals or interested amateurs now consult extensive benchmark
Benchmark (computing)
In computing, a benchmark is the act of running a computer program, a set of programs, or other operations, in order to assess the relative performance of an object, normally by running a number of standard tests and trials against it...
tests to determine system performance on various applications.