Editing Performance Rating

{{About|rating computer CPU performance|performance rating at the workplace|performance rating (work measurement)|chess ratings|rating performance (chess)}}
{{short description|Figure of merit developed by AMD, Cyrix, IBM Microelectronics and SGS-Thomson}}

The '''PR''' ('''performance rating''', '''P-rating''', or '''Pentium rating''') system was a [[figure of merit]] developed by [[AMD]], [[Cyrix]], [[IBM Microelectronics]] and [[SGS-Thomson]] in the mid-1990s as a method of comparing their [[x86]] processors to those of rival [[Intel]]. The idea was to consider [[instructions per cycle]] (IPC) in addition to the clock speed, so that the processors become comparable with Intel's Pentium that had a higher clock speed with overall lower IPC.<ref name=":0">{{Cite magazine|url=https://books.google.com/books?id=K8IS2A_xDLUC&q=%22P-Rating%22&pg=PA31|title=Trends: Cyrix Scores|last=Metz|first=Cade|date=1996-04-09|magazine=[[PC Magazine]]|publisher=[[Ziff Davis, Inc.]]|volume=15|pages=31|language=en|issue=7}}</ref><ref>{{Cite web|url=http://www.cyrix.com/corpor/press/1996/pratg-pr.htm|title=Cyrix Corporate Information -- New P-Rating System for Microprocessors Simplifies Consumer Evaluation of Personal Computers|date=1996-02-05|url-status=live|archive-url=https://web.archive.org/web/19960926233116/http://www.cyrix.com/corpor/press/1996/pratg-pr.htm|archive-date=1996-09-26|access-date=2019-12-17}}</ref>

== Branding ==
The first use of the PR system was in 1995, when AMD used it to assert that their [[AMD 5x86]] processor was as fast as a [[Pentium (original)|Pentium]] running at 75 MHz. The designation "P75" was added to the chip to denote this.<ref name=pcgamer>{{Cite web|last=Lilly|first=Paul|date=2009-04-14|title=A Brief History of CPUs: 31 Awesome Years of x86|url=https://www.pcgamer.com/a-brief-history-of-cpus-31-awesome-years-of-x86/|access-date=2023-08-18|website=[[PC Gamer]]|language=en|df=mdy}}</ref>{{rp|3}}  Later that year, [[Cyrix]] also adopted the PR system for its [[6x86]]<ref name=":0" /> and [[6x86MX]] line of processors.{{fact|date=August 2023}} These processors were faster than Pentiums of the same speed in some benchmarks, so Cyrix gave them a Performance Rating faster than their clock speed.<ref name=pcgamer/> Some [[AMD K5]] models also use the PR system. 

AMD initially branded its [[AMD K6]] processors with a "PR2" rating but dropped this after consumer confusion.<ref>{{cite web|url=https://www.anandtech.com/show/42/amd-k6-review|title=AMD K6 Review|last=Shimpi|first=Anand Lal|work=[[AnandTech]]|date=1997-04-03|accessdate=2023-08-18}}</ref>  AMD revived the branding for its [[Athlon XP]], which was released in 2001.  The efficient Athlon XP chips could perform better than similarly-clocked chips from Intel's competing [[Pentium 4]] line-up, which depended on high clock speeds to overcome their low IPC.  As a result, AMD believed consumers would be swayed by the [[megahertz myth]].<ref>{{cite web |last=McLaughlin |first=Laurianne |url=http://www.pcworld.com/article/65171/amd_strikes_back.html |title=AMD Strikes Back |work=[[PC World]] |date=2001-11-02 |access-date=2012-01-08|archive-url=https://web.archive.org/web/20120420111758/https://www.pcworld.com/article/65171/amd_strikes_back.html|archive-date=2012-04-20}}</ref>  These chips were rated against the [[Athlon Thunderbird]] but were popularly compared to the Pentium 4.  As a result, the branding became colloquially known as a "Pentium Rating".<ref name=pcgamer/>{{rp|6}}  ''[[Maximum PC]]'' criticized this as making it more difficult for power users to differentiate between the various Athlon XP chips.  For example, two chips could be given the same "PR" branding but have much different engineering ([[CPU cache|cache]] size, [[bus (computing)|bus]] speed, etc), which would affect their performance at different tasks.<ref>{{cite book|title=Maximum PC Guide to Building a Dream PC|chapter=AMD, the Feisty Upstart|last=Smith|first=Will|publisher=[[Que Publishing]]|year=2005|isbn=0-7897-3193-2|page=48|chapter-url=https://books.google.com/books?id=Cnj_3fFfPdsC&pg=PA48}}</ref>

==See also==
* [[iCOMP (index)]]

== References ==
{{reflist}}

== External links ==
* [https://en.wikichip.org/wiki/processor_performance_rating_(p-rating)_specification Processor Performance Rating (P-rating) Specification], February 1996. Uses Winstone 96.
* [https://en.wikichip.org/wiki/p-rating P-rating] on wikichip

[[Category:AMD]]
[[Category:Rating systems]]
[[Category:Computer performance]]