Computer hardware: Difference between revisions

Revision as of 11:49, 19 August 2025

Revision as of 10:39, 20 August 2025

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*[[Random-access memory]] (RAM) stores code and data actively used by the CPU, organized in a [[memory hierarchy]] optimized for access speed and predicted reuse. At the top of this hierarchy are [[processor register|registers]], located within the CPU core, offering the fastest access but extremely limited capacity.{{sfn|Wang|2021|p=47}} Below registers are multiple levels of [[cache memory]]—L1, L2, and sometimes L3—typically implemented using [[static random-access memory]] (SRAM). Caches have greater capacity than registers but less than main memory, and while slower than registers, they are significantly faster than [[dynamic random-access memory]] (DRAM), which is used for main RAM.{{sfn|Wang|2021|pp=49–50}} Caching improves performance by [[prefetching]] frequently used data, thereby reducing [[memory latency]].{{sfn|Wang|2021|pp=49–50}}{{sfn|Hennessy|Patterson|2011|p=45}} When data is not found in the cache (a [[cache miss]]), it is retrieved from main memory. RAM is volatile, meaning its contents are lost when the system loses power.{{sfn|Wang|2021|p=54}} In modern systems, DRAM is often of the [[DDR SDRAM]] type, such as DDR4 or DDR5.

*Permanent storage or non-volatile memory is typically higher capacity and cheaper than memory, but takes much longer to access. Historically, such storage was typically provided in the form of a hard drive, but [[solid-state drives]] (SSD) are becoming cheaper and are much faster, thus leading to their increasing adoption. USB drives and network or cloud storage are also options.{{sfn|Wang|2021|pp=55–56}}

*[[Read-only memory]] (ROM), whichcontains storesfirmware such as the [[BIOS]] that(Basic runsInput/Output whenSystem), thewhich computerinitializes ishardware poweredduring onthe orboot otherwiseprocess—known beginsas execution,[[booting]] a process known asor [[Bootstrappingbootstrapping (computing)|Bootstrappingbootstrapping]],—when orthe [[booting]]computer oris bootingpowered upon.{{cn|date=August 2024}} TheThis ROMfirmware is typicallystored in a non-volatile memory chip, traditionally ROM or [[nonvolatile BIOSflash memory]] chip, whichallowing canupdates onlyin bemodern writtensystems oncevia with[[firmware special technologyupdate]].{{sfn|Wang|2021|p=55}}

** The [[BIOS]] (Basicmanages Inputessential Outputfunctions System) includesincluding boot [[firmware]]sequence and power management firmwarethrough the [[ACPI]] standard. NewerHowever, most modern motherboards usehave transitioned to the [[Unified Extensible Firmware Interface]] (UEFI), insteadwhich ofoffers BIOSenhanced capabilities, faster startup times, support for [[GUID Partition Table]] (GPT), and secure boot features.

* The [[CMOS]] (complementary MOS) [[electric battery|battery]], which powers the [[CMOS memory]] for date and time in the BIOS chip. This battery is generally a [[watch battery]].

*[[Power MOSFET]]s make up the [[voltage regulator module]] (VRM), which controls how much [[voltage]] other hardware components receive.<ref name="tomshardware">{{cite web |last1=Harding |first1=Scharon |title=What Is a MOSFET? A Basic Definition |url=https://www.tomshardware.com/uk/reviews/mosfet-defintion-transistor-pc-motherboard-psu-explained,6343.html |website=[[Tom's Hardware]] |access-date=7 November 2019 |date=September 17, 2019}}</ref>