Random-access memory: Difference between revisions

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[[File:Random Access Memory HyperX.jpg|thumb|8GB [[DDR3]] [[RAM]] stick with a white [[Heat sink|heatsink]]]]

'''Random-access memory''' ('''RAM'''; {{IPAc-en|r|æ|m}}) is a form of [[Computer memory|electronic computer memory]] that can be read and changed in any order, typically used to store working [[Data (computing)|data]] and [[machine code]].<ref>{{cite web |title=RAM |url=https://dictionary.cambridge.org/dictionary/english/ram |website=[[Cambridge English Dictionary]] |access-date=11 July 2019}}</ref><ref>{{cite web |title=RAM |url=https://www.oxfordlearnersdictionaries.com/definition/american_english/ram_2 |website=[[Oxford Advanced Learner's Dictionary]] |access-date=11 July 2019}}</ref> A [[Random access|random-access]] memory device allows data items to be [[read (computer)|read]] or written in almost the same amount of time irrespective of the physical ___location of data inside the memory, in contrast with other direct-access data storage media (such as [[hard disk]]s and [[Magnetic tape data storage|magnetic tape]]), where the time required to read and write data items varies significantly depending on their physical locations on the recording medium, due to mechanical limitations such as media rotation speeds and arm movement.<!--[[User:Kvng/RTH]]-->

In today's technology, random-access memory takes the form of [[integrated circuit]] (IC) chips with [[MOSFET|MOS]] (metal–oxide–semiconductor) [[Memory cell (computing)|memory cells]]. RAM is normally associated with [[Volatile memory|volatile]] types of memory where stored information is lost if power is removed. The two main types of volatile random-access [[semiconductor memory]] are [[static random-access memory]] (SRAM) and [[dynamic random-access memory]] (DRAM).

Non-volatile RAM has also been developed<ref>{{cite magazine|last=Gallagher|first=Sean|title=Memory that never forgets: non-volatile DIMMs hit the market|url=https://arstechnica.com/information-technology/2013/04/memory-that-never-forgets-non-volatile-dimms-hit-the-market/|magazine=[[Ars Technica]]|url-status=live|archive-url=https://web.archive.org/web/20170708073138/https://arstechnica.com/information-technology/2013/04/memory-that-never-forgets-non-volatile-dimms-hit-the-market/|archive-date=July 8, 2017|date=April 4, 2013}}</ref> and other types of [[Non-volatile memory|non-volatile memories]] allow random access for read operations, but either do not allow write operations or have other kinds of limitations. These include most types of [[read-only memory|ROM]] and [[NOR flash memory]].<!--[[User:Kvng/RTH]]-->

and other types of [[Non-volatile memory|non-volatile memories]] allow random access for read operations, but either do not allow write operations or have other kinds of limitations on them. These include most types of [[read-only memory|ROM]] and a type of [[flash memory]] called ''[[flash memory#NOR flash|NOR-Flash]]''.

Use of semiconductor RAM dated back to 1965, when IBM introduced the monolithic (single-chip) 16-bit SP95 SRAM chip for their [[IBM System/360|System/360 Model 95]] computer, and [[Toshiba]] used discrete DRAM memory cells for its 180-bit Toscal BC-1411 [[electronic calculator]], both based on [[bipolar transistor]]s. While it offered higher speeds than [[magnetic-core memory]], bipolar DRAM could not compete with the lower price of the then-dominant magnetic-core memory.<ref>{{cite web |title=1966: Semiconductor RAMs Serve High-speed Storage Needs |url=https://www.computerhistory.org/siliconengine/semiconductor-rams-serve-high-speed-storage-needs/ |website=Computer History Museum}}</ref>