Editing Central processing unit (section)

{{Short description|Central computer component that executes instructions}}
{{Redirect|CPU}}

[[File:Intel_i9-14900KF_CPU.jpg|thumb|A modern high-end consumer CPU made by [[Intel]]: An [[Intel Core i9-14900KF]]]]

[[File:Intel Xeon 3060 Conroe (Reshoot) - Flickr - cole8888.jpg|thumb|280px|upright=1.5|Inside a central processing unit: The [[integrated circuit]] of Intel's [[List of Intel Xeon processors (Core-based)#ark27205|Xeon 3060]], first manufactured in 2006]]

A '''central processing unit''' ('''CPU'''), also called a '''central processor''', '''main processor''', or just '''processor''', is the primary [[Processor (computing)|processor]] in a given [[computer]].<ref>{{Cite book |last=Team |first=YCT Expert |url=https://books.google.com/books?id=O_fZEAAAQBAJ&dq=A+central+processing+unit+(CPU)%E2%80%94also+called+a+central+processor+or+main+processor%E2%80%94is+the+most+important+processor+in+a+given+computer.&pg=PA425 |title=Engineering Drawing & Basic Science |publisher=Youth Competition Times |pages=425 |language=en}}</ref><ref>{{Cite book |last=Nagpal |first=D. P. |url=https://books.google.com/books?id=LAsbEAAAQBAJ&dq=A+central+processing+unit+(CPU)%E2%80%94also+called+a+central+processor+or+main+processor%E2%80%94is+the+most+important+processor+in+a+given+computer.&pg=PA33 |title=Computer Fundamentals |date=2008 |publisher=S. Chand Publishing |isbn=978-81-219-2388-0 |pages=33 |language=en}}</ref> Its [[electronic circuit]]ry executes [[Instruction (computing)|instructions]] of a [[computer program]], such as [[arithmetic]], logic, controlling, and [[input/output]] (I/O) operations.<ref>{{Cite web |title=What is processor (CPU)? A definition from WhatIs.com |url=https://www.techtarget.com/whatis/definition/processor |access-date=2024-03-15 |website=WhatIs |language=en}}</ref><ref>{{Cite book |last=Chesalov |first=Alexander |url=https://books.google.com/books?id=VlG5EAAAQBAJ&dq=cpu+electronic+circuitry+executes+instructions+of+a+computer+program,+such+as+arithmetic,+logic,+controlling,+and+input/output+(I/O)+operations&pg=PT54 |title=The fourth industrial revolution glossarium: over 1500 of the hottest terms you will use to create the future |date=2023-04-12 |publisher=Litres |isbn=978-5-04-541163-9 |language=en}}</ref><ref>{{Cite book |last=Jagare |first=Ulrika |url=https://books.google.com/books?id=ZwxsEAAAQBAJ&dq=cpu+electronic+circuitry+executes+instructions+of+a+computer+program,+such+as+arithmetic,+logic,+controlling,+and+input/output+(I/O)+operations&pg=PT91 |title=Operating AI: Bridging the Gap Between Technology and Business |date=2022-04-19 |publisher=John Wiley & Sons |isbn=978-1-119-83321-5 |language=en}}</ref> This role contrasts with that of external components, such as [[main memory]] and I/O circuitry,<ref name="kuck">{{cite book|last1= Kuck|first1= David|title= Computers and Computations, Vol 1|date= 1978|publisher= John Wiley & Sons, Inc.|isbn= 978-0471027164|page= 12}}</ref> and specialized [[coprocessor]]s such as [[graphics processing unit]]s (GPUs).

The form, [[CPU design|design]], and implementation of CPUs have changed over time, but their fundamental operation remains almost unchanged.<ref>{{Cite book |last=Prabhat |first=Team |url=https://books.google.com/books?id=sbqcEAAAQBAJ&dq=design,+and+implementation+of+CPUs+have+changed+over+time,+but+their+fundamental+operation+remains+almost+unchanged.&pg=PA95 |title=Ultimate Guide to SSC CGL Combined Graduate Level Tier-I & Tier II Prelims & Mains (with Latest Solved Question Papers) Guide Book English: Bestseller Book by Team Prabhat: Ultimate Guide to SSC CGL Combined Graduate Level Tier-I & Tier II Prelims & Mains (with Latest Solved Question Papers) Guide Book English |date=2023-04-13 |publisher=Prabhat Prakashan |isbn=978-93-5488-527-3 |pages=95 |language=en}}</ref> Principal components of a CPU include the [[arithmetic–logic unit]] (ALU) that performs [[arithmetic operation|arithmetic]] and [[Bitwise operation|logic operations]], [[processor register]]s that supply [[operand]]s to the ALU and store the results of ALU operations, and a [[control unit]] that orchestrates the [[#Fetch|fetching (from memory)]], [[#Decode|decoding]] and [[#Execute|execution (of instructions)]] by directing the coordinated operations of the ALU, registers, and other components. Modern CPUs devote a lot of semiconductor area to [[Cache (computing)|caches]] and [[instruction-level parallelism]] to increase performance and to [[CPU modes]] to support [[operating system]]s and [[virtualization]].

Most modern CPUs are implemented on [[integrated circuit]] (IC) [[microprocessor]]s, with one or more CPUs on a single IC chip. Microprocessor chips with multiple CPUs are called ''[[multi-core processor]]s''.<ref>{{Cite web |title=What is a multicore processor and how does it work? |url=https://www.techtarget.com/searchdatacenter/definition/multi-core-processor |access-date=2024-03-15 |website=Data Center |language=en}}</ref> The individual physical CPUs, called '''''processor cores''''', can also be [[Multithreading (computer architecture)|multithreaded]] to support CPU-level multithreading.<ref name="intel-pcm" />

An IC that contains a CPU may also contain [[Computer memory|memory]], [[peripheral]] interfaces, and other components of a computer;<ref>{{Cite book |last=Herres |first=David |url=https://books.google.com/books?id=RYoBEAAAQBAJ&dq=An+IC+that+contains+a+CPU+may+also+contain+memory&pg=PA130 |title=Oscilloscopes: A Manual for Students, Engineers, and Scientists |date=2020-10-06 |publisher=Springer Nature |isbn=978-3-030-53885-9 |pages=130 |language=en}}</ref> such integrated devices are variously called [[microcontroller]]s or [[System on a chip|systems on a chip]] (SoC).