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imported>Klbrain Closing; no merge; see Talk:Computer memory#Proposed merge of Data in use into Computer memory |
imported>MusikBot II m Adding missing protection template (more info) |
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{{Short description|Component that stores information}} | {{Short description|Component that stores information}} | ||
{{Use American English|date=June 2023}} | {{Use American English|date=June 2023}} | ||
[[File:RAM Module (SDRAM-DDR4).jpg|thumb|[[DDR4 SDRAM]] module. {{As of|2021}}, over 90 percent of computer memory used in PCs and servers was of this type.<ref>{{cite news |last1=Read |first1=Jennifer |title=DDR5 Era To Officially Begin In 2021, With DRAM Market Currently Transitioning Between Generations, Says TrendForce |url=https://www.emsnow.com/ddr5-era-to-officially-begin-in-2021-with-dram-market-currently-transitioning-between-generations-says-trendforce/ |access-date=2 November 2022 |publisher=EMSNow |date=5 November 2020}}</ref>]] | |||
[[File:RAM Module (SDRAM-DDR4).jpg|thumb|[[DDR4 SDRAM]] module. {{As of|2021}}, over 90 percent of computer memory used in PCs and servers was of this type.<ref>{{cite news |last1=Read |first1=Jennifer |title=DDR5 Era To Officially Begin In 2021, With DRAM Market Currently Transitioning Between Generations, Says TrendForce |url=https://www.emsnow.com/ddr5-era-to-officially-begin-in-2021-with-dram-market-currently-transitioning-between-generations-says-trendforce/ |access-date=2 November 2022 |publisher=EMSNow |date=5 November 2020}}</ref> |alt=An orange metal heatsink covers the RAM ICs, which are soldered to the printed circuitboard underneath the heatsink. Part of the printed circuit board can be seen as a strip of green below the heatsink. Gold contacts that are inserted into the computer are at the very bottom.]] | |||
{{Memory types}} | {{Memory types}} | ||
'''Computer memory''' stores information, such as data and programs, for immediate use in the [[computer]] | '''Computer memory''' stores information, such as data and programs, for immediate use in the [[computer]];<ref name=":1">{{cite web |last1=Hemmendinger |first1=David |title=Computer memory |url=https://www.britannica.com/technology/computer-memory |website=[[Encyclopedia Britannica]] |access-date=16 October 2019 |date=February 15, 2016}}</ref> [[instruction set|instructions]] fetched by the computer, and data fetched and stored by those instructions, are located in computer memory. The terms ''memory'', ''[[main memory]]'', and ''[[primary storage]]'' are also used for computer memory. | ||
Computer memory is often referred to as ''RAM'', meaning [[random-access memory]], although some older forms of computer memory, such as [[drum memory]], are not random-access. Archaic synonyms for main memory include ''core'' (for [[magnetic-core memory]]) and ''store''.<ref>{{cite book |author-link1=Alan Turing |author1=A.M. Turing |author2=R.A. Brooker |date=1952 |chapter-url=http://www.alanturing.net/turing_archive/archive/m/m01/M01-005.html |chapter=1. General remarks on electronic computers |title=Programmer's Handbook for Manchester Electronic Computer Mark II |url-status=live |archive-url=https://web.archive.org/web/20140102231704/http://www.alanturing.net/turing_archive/archive/m/m01/M01-005.html |archive-date=2014-01-02 |publisher=[[University of Manchester]]}}</ref> | |||
Main memory operates at a high speed compared to [[mass storage]] which is slower but less expensive per bit and higher in capacity. Besides storing opened programs and data being actively processed, computer memory serves as a [[Page cache|mass storage cache]] and [[write buffer]] to improve both reading and writing performance. Operating systems borrow [[RAM]] capacity for caching so long as it is not needed by running software.<ref>{{cite web| url = https://www.kernel.org/doc/html/latest/admin-guide/sysctl/vm.html| title = Documentation for /proc/sys/vm/}}</ref> If needed, contents of the computer memory can be transferred to storage; a common way of doing this is through a memory management technique called ''[[virtual memory]]''. | Main memory operates at a high speed compared to [[mass storage]] which is slower but less expensive per bit and higher in capacity. Besides storing opened programs and data being actively processed, computer memory serves as a [[Page cache|mass storage cache]] and [[write buffer]] to improve both reading and writing performance. Operating systems typically borrow [[RAM]] capacity for caching so long as it is not needed by running software.<ref>{{cite web| url = https://www.kernel.org/doc/html/latest/admin-guide/sysctl/vm.html| title = Documentation for /proc/sys/vm/}}</ref> If needed, contents of the computer memory can be transferred to storage; a common way of doing this is through a memory management technique called ''[[virtual memory]]''. | ||
Modern computer memory is implemented as [[semiconductor memory]],<ref>{{cite web |title=The MOS Memory Market |url=http://smithsonianchips.si.edu/ice/cd/MEMORY97/SEC01.PDF |archive-url=https://web.archive.org/web/20030725103322/http://smithsonianchips.si.edu/ice/cd/MEMORY97/SEC01.PDF |archive-date=2003-07-25 |url-status=live |website=Integrated Circuit Engineering Corporation |publisher=[[Smithsonian Institution]] |year=1997 |access-date=16 October 2019}}</ref><ref>{{cite web |title=MOS Memory Market Trends |url=http://smithsonianchips.si.edu/ice/cd/STATUS98/SEC07.PDF |archive-url=https://web.archive.org/web/20191016225542/http://smithsonianchips.si.edu/ice/cd/STATUS98/SEC07.PDF |archive-date=2019-10-16 |url-status=live |website=Integrated Circuit Engineering Corporation |publisher=[[Smithsonian Institution]] |year=1998 |access-date=16 October 2019}}</ref> where data is stored within [[memory cell (computing)|memory cells]] built from [[MOS transistor]]s and other components on an [[integrated circuit]].<ref name="computerhistory">{{cite journal|url=https://www.computerhistory.org/siliconengine/metal-oxide-semiconductor-mos-transistor-demonstrated/|title=1960 - Metal Oxide Semiconductor (MOS) Transistor Demonstrated|journal=The Silicon Engine|publisher=[[Computer History Museum]]}}</ref> There are two main kinds of semiconductor memory: [[volatile memory|volatile]] and [[non-volatile]]. Examples of [[non-volatile memory]] are [[flash memory]] and [[ROM]], [[Programmable read-only memory|PROM]], [[EPROM]], and [[EEPROM]] memory. Examples of [[volatile memory]] are [[dynamic random-access memory]] (DRAM) used for primary storage and [[static random-access memory]] (SRAM) used mainly for [[CPU cache]]. | Modern computer memory is implemented as [[semiconductor memory]],<ref>{{cite web |title=The MOS Memory Market |url=http://smithsonianchips.si.edu/ice/cd/MEMORY97/SEC01.PDF |archive-url=https://web.archive.org/web/20030725103322/http://smithsonianchips.si.edu/ice/cd/MEMORY97/SEC01.PDF |archive-date=2003-07-25 |url-status=live |website=Integrated Circuit Engineering Corporation |publisher=[[Smithsonian Institution]] |year=1997 |access-date=16 October 2019}}</ref><ref>{{cite web |title=MOS Memory Market Trends |url=http://smithsonianchips.si.edu/ice/cd/STATUS98/SEC07.PDF |archive-url=https://web.archive.org/web/20191016225542/http://smithsonianchips.si.edu/ice/cd/STATUS98/SEC07.PDF |archive-date=2019-10-16 |url-status=live |website=Integrated Circuit Engineering Corporation |publisher=[[Smithsonian Institution]] |year=1998 |access-date=16 October 2019}}</ref> where data is stored within [[memory cell (computing)|memory cells]] built from [[MOS transistor]]s and other components on an [[integrated circuit]].<ref name="computerhistory">{{cite journal|url=https://www.computerhistory.org/siliconengine/metal-oxide-semiconductor-mos-transistor-demonstrated/|title=1960 - Metal Oxide Semiconductor (MOS) Transistor Demonstrated|journal=The Silicon Engine|publisher=[[Computer History Museum]]}}</ref> There are two main kinds of semiconductor memory: [[volatile memory|volatile]] and [[non-volatile]]. Examples of [[non-volatile memory]] are [[flash memory]] and [[ROM]], [[Programmable read-only memory|PROM]], [[EPROM]], and [[EEPROM]] memory. Examples of [[volatile memory]] are [[dynamic random-access memory]] (DRAM) used for primary storage and [[static random-access memory]] (SRAM) used mainly for [[CPU cache]]. | ||
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The next significant advance in computer memory came with acoustic [[delay-line memory]], developed by [[J. Presper Eckert]] in the early 1940s. Through the construction of a glass tube filled with [[mercury (element)|mercury]] and plugged at each end with a quartz crystal, delay lines could store [[bits of information]] in the form of sound waves propagating through the mercury, with the quartz crystals acting as [[transducer]]s to read and write bits. Delay-line memory was limited to a capacity of up to a few thousand bits. | The next significant advance in computer memory came with acoustic [[delay-line memory]], developed by [[J. Presper Eckert]] in the early 1940s. Through the construction of a glass tube filled with [[mercury (element)|mercury]] and plugged at each end with a quartz crystal, delay lines could store [[bits of information]] in the form of sound waves propagating through the mercury, with the quartz crystals acting as [[transducer]]s to read and write bits. Delay-line memory was limited to a capacity of up to a few thousand bits. | ||
Two alternatives to the delay line, the [[Williams tube]] and [[Selectron tube]], originated in 1946, both using electron beams in glass tubes as means of storage. Using [[cathode | Two alternatives to the delay line, the [[Williams tube]] and [[Selectron tube]], originated in 1946, both using electron beams in glass tubes as means of storage. Using [[cathode ray tube]]s, Fred Williams invented the Williams tube, which was the first [[random-access memory|random-access computer memory]]. The Williams tube was able to store more information than the Selectron tube (the Selectron was limited to 256 bits, while the Williams tube could store thousands) and was less expensive. The Williams tube was nevertheless frustratingly sensitive to environmental disturbances. | ||
Efforts began in the late 1940s to find [[non-volatile memory]]. [[Magnetic-core memory]] allowed for memory recall after power loss. It was developed by Frederick W. Viehe and [[An Wang]] in the late 1940s, and improved by [[Jay Forrester]] and [[Jan A. Rajchman]] in the early 1950s, before being commercialized with the [[Whirlwind I]] computer in 1953.<ref>{{cite web |title=1953: Whirlwind computer debuts core memory |url=https://www.computerhistory.org/storageengine/whirlwind-computer-debuts-core-memory/ |website=[[Computer History Museum]] |access-date=2 August 2019}}</ref> Magnetic-core memory was the dominant form of memory until the development of [[MOSFET|MOS]] [[semiconductor memory]] in the 1960s.<ref name="computerhistory1966" /> | Efforts began in the late 1940s to find [[non-volatile memory]]. [[Magnetic-core memory]] allowed for memory recall after power loss. It was developed by Frederick W. Viehe and [[An Wang]] in the late 1940s, and improved by [[Jay Forrester]] and [[Jan A. Rajchman]] in the early 1950s, before being commercialized with the [[Whirlwind I]] computer in 1953.<ref>{{cite web |title=1953: Whirlwind computer debuts core memory |url=https://www.computerhistory.org/storageengine/whirlwind-computer-debuts-core-memory/ |website=[[Computer History Museum]] |access-date=2 August 2019}}</ref> Magnetic-core memory was the dominant form of memory until the development of [[MOSFET|MOS]] [[semiconductor memory]] in the 1960s.<ref name="computerhistory1966" /> | ||
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The two main types of volatile [[random-access memory]] (RAM) are [[static random-access memory]] (SRAM) and [[dynamic random-access memory]] (DRAM). Bipolar SRAM was invented by Robert Norman at Fairchild Semiconductor in 1963,<ref name="computerhistory1966"/> followed by the development of MOS SRAM by John Schmidt at Fairchild in 1964.<ref name="computerhistory1970"/> SRAM became an alternative to magnetic-core memory, but requires six transistors for each [[bit]] of data.<ref name="ibm100">{{cite web |title=DRAM |url=https://www.ibm.com/ibm/history/ibm100/us/en/icons/dram/ |website=IBM100 |publisher=[[IBM]] |access-date=20 September 2019 |date=9 August 2017}}</ref> Commercial use of SRAM began in 1965, when IBM introduced their SP95 SRAM chip for the [[IBM System/360|System/360 Model 95]].<ref name="computerhistory1966"/> | The two main types of volatile [[random-access memory]] (RAM) are [[static random-access memory]] (SRAM) and [[dynamic random-access memory]] (DRAM). Bipolar SRAM was invented by Robert Norman at Fairchild Semiconductor in 1963,<ref name="computerhistory1966"/> followed by the development of MOS SRAM by John Schmidt at Fairchild in 1964.<ref name="computerhistory1970"/> SRAM became an alternative to magnetic-core memory, but requires six transistors for each [[bit]] of data.<ref name="ibm100">{{cite web |title=DRAM |url=https://www.ibm.com/ibm/history/ibm100/us/en/icons/dram/ |website=IBM100 |publisher=[[IBM]] |access-date=20 September 2019 |date=9 August 2017}}</ref> Commercial use of SRAM began in 1965, when IBM introduced their SP95 SRAM chip for the [[IBM System/360|System/360 Model 95]].<ref name="computerhistory1966"/> | ||
[[Toshiba]] introduced bipolar DRAM [[Memory cell (computing)|memory cells]] for its Toscal BC-1411 [[electronic calculator]] in 1965.<ref name="bc-spec">{{cite web|url=http://www.oldcalculatormuseum.com/s-toshbc1411.html|title=Spec Sheet for Toshiba "TOSCAL" BC-1411|website=Old Calculator Web Museum|access-date=8 May 2018|url-status=live|archive-url=https://web.archive.org/web/20170703071307/http://www.oldcalculatormuseum.com/s-toshbc1411.html|archive-date=3 July 2017}}</ref><ref name="bc">{{cite web |url=http://www.oldcalculatormuseum.com/toshbc1411.html |title=Toshiba "Toscal" BC-1411 Desktop Calculator |archive-url=https://web.archive.org/web/20070520202433/http://www.oldcalculatormuseum.com/toshbc1411.html |archive-date=2007-05-20}}</ref> While it offered improved performance, 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> MOS technology is the basis for modern DRAM. In 1966, [[Robert H. Dennard]] at the [[IBM Thomas J. Watson Research Center]] was working on MOS memory. While examining the characteristics of MOS technology, he found it was possible to build [[capacitors]], and that storing a charge or no charge on the MOS capacitor could represent the 1 and 0 of a bit, while the MOS transistor could control writing the charge to the capacitor. This led to his development of a single-transistor DRAM memory cell.<ref name="ibm100"/> In 1967, Dennard filed a patent for a single-transistor DRAM memory cell based on MOS technology.<ref>{{cite web |title=Robert Dennard |url=https://www.britannica.com/biography/Robert-Dennard |website=[[Encyclopedia Britannica]] |access-date=8 July 2019}}</ref> This led to the first commercial DRAM IC chip, the [[Intel 1103]] in October 1970.<ref name="Intel2003">{{cite web |title=Intel: 35 Years of Innovation (1968–2003) |url=https://www.intel.com/Assets/PDF/General/35yrs.pdf |publisher=Intel |year=2003 |access-date=26 June 2019 |archive-url=https://web.archive.org/web/20211104070452/https://www.intel.com/Assets/PDF/General/35yrs.pdf |archive-date=4 November 2021 |url-status=dead}}</ref><ref name="HC"> | [[Toshiba]] introduced bipolar DRAM [[Memory cell (computing)|memory cells]] for its Toscal BC-1411 [[electronic calculator]] in 1965.<ref name="bc-spec">{{cite web|url=http://www.oldcalculatormuseum.com/s-toshbc1411.html|title=Spec Sheet for Toshiba "TOSCAL" BC-1411|website=Old Calculator Web Museum|access-date=8 May 2018|url-status=live|archive-url=https://web.archive.org/web/20170703071307/http://www.oldcalculatormuseum.com/s-toshbc1411.html|archive-date=3 July 2017}}</ref><ref name="bc">{{cite web |url=http://www.oldcalculatormuseum.com/toshbc1411.html |title=Toshiba "Toscal" BC-1411 Desktop Calculator |archive-url=https://web.archive.org/web/20070520202433/http://www.oldcalculatormuseum.com/toshbc1411.html |archive-date=2007-05-20}}</ref> While it offered improved performance, 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> MOS technology is the basis for modern DRAM. In 1966, [[Robert H. Dennard]] at the [[IBM Thomas J. Watson Research Center]] was working on MOS memory. While examining the characteristics of MOS technology, he found it was possible to build [[capacitors]], and that storing a charge or no charge on the MOS capacitor could represent the 1 and 0 of a bit, while the MOS transistor could control writing the charge to the capacitor. This led to his development of a single-transistor DRAM memory cell.<ref name="ibm100"/> In 1967, Dennard filed a patent for a single-transistor DRAM memory cell based on MOS technology.<ref>{{cite web |title=Robert Dennard |url=https://www.britannica.com/biography/Robert-Dennard |website=[[Encyclopedia Britannica]] |access-date=8 July 2019}}</ref> This led to the first commercial DRAM IC chip, the [[Intel 1103]] in October 1970.<ref name="Intel2003">{{cite web |title=Intel: 35 Years of Innovation (1968–2003) |url=https://www.intel.com/Assets/PDF/General/35yrs.pdf |publisher=Intel |year=2003 |access-date=26 June 2019 |archive-url=https://web.archive.org/web/20211104070452/https://www.intel.com/Assets/PDF/General/35yrs.pdf |archive-date=4 November 2021 |url-status=dead}}</ref><ref name="HC">{{cite web |url=http://history-computer.com/ModernComputer/Basis/dram.html |url-status=dead |archive-url=https://web.archive.org/web/20110220214144/http://history-computer.com/ModernComputer/Basis/dram.html |archive-date=2011-02-20 |title=The DRAM memory of Robert Dennard |website=history-computer.com}}</ref><ref name="Lojek-1103">{{cite book |last1=Lojek |first1=Bo |title=History of Semiconductor Engineering |date=2007 |publisher=[[Springer Science & Business Media]] |isbn=9783540342588 |pages=362–363 |url=https://books.google.com/books?id=2cu1Oh_COv8C&pg=PA362 |quote=The i1103 was manufactured on a 6-mask silicon-gate P-MOS process with 8 μm minimum features. The resulting product had a 2,400 µm, 2 memory cell size, a die size just under 10 mm², and sold for around $21.}}</ref> [[Synchronous dynamic random-access memory]] (SDRAM) later debuted with the [[Samsung Electronics|Samsung]] KM48SL2000 chip in 1992.<ref>{{cite web |title=KM48SL2000-7 Datasheet |url=https://www.datasheetarchive.com/KM48SL2000-7-datasheet.html |publisher=[[Samsung]] |access-date=19 June 2019 |date=August 1992}}</ref><ref name="electronic-design">{{cite journal |title=Electronic Design |journal=[[Electronic Design]] |date=1993 |volume=41 |issue=15–21 |url=https://books.google.com/books?id=QmpJAQAAIAAJ |publisher=Hayden Publishing Company |quote=The first commercial synchronous DRAM, the Samsung 16-Mbit KM48SL2000, employs a single-bank architecture that lets system designers easily transition from asynchronous to synchronous systems.}}</ref> | ||
The term ''memory'' is also often used to refer to [[non-volatile memory]] including [[read-only memory]] (ROM) through modern [[flash memory]]. [[Programmable read-only memory]] (PROM) was invented by [[Wen Tsing Chow]] in 1956, while working for the Arma Division of the American Bosch Arma Corporation.<ref name="Huang2008">{{cite book|author=Han-Way Huang|title=Embedded System Design with C805|url=https://books.google.com/books?id=3zRtCgAAQBAJ&pg=PA22|date=5 December 2008|publisher=Cengage Learning|isbn=978-1-111-81079-5|page=22|url-status=live|archive-url=https://web.archive.org/web/20180427092847/https://books.google.com/books?id=3zRtCgAAQBAJ&pg=PA22|archive-date=27 April 2018}}</ref><ref name="AufaureZimányi2013">{{cite book|author1=Marie-Aude Aufaure|author2=Esteban Zimányi|title=Business Intelligence: Second European Summer School, eBISS 2012, Brussels, Belgium, July 15-21, 2012, Tutorial Lectures|url=https://books.google.com/books?id=7iK5BQAAQBAJ&pg=PA136|date=17 January 2013|publisher=Springer|isbn=978-3-642-36318-4|page=136|url-status=live|archive-url=https://web.archive.org/web/20180427092847/https://books.google.com/books?id=7iK5BQAAQBAJ&pg=PA136|archive-date=27 April 2018}}</ref> In 1967, Dawon Kahng and [[Simon Sze]] of Bell Labs proposed that the [[floating gate]] of a MOS [[semiconductor device]] could be used for the cell of a reprogrammable ROM, which led to [[Dov Frohman]] of [[Intel]] inventing [[EPROM]] (erasable PROM) in 1971.<ref name="computerhistory1971">{{cite web |title=1971: Reusable semiconductor ROM introduced |url=https://www.computerhistory.org/storageengine/reusable-semiconductor-rom-introduced/ |website=[[Computer History Museum]] |access-date=19 June 2019}}</ref> [[EEPROM]] (electrically erasable PROM) was developed by Yasuo Tarui, Yutaka Hayashi and Kiyoko Naga at the [[Electrotechnical Laboratory]] in 1972.<ref>{{cite journal|last1=Tarui|first1=Y.|last2=Hayashi|first2=Y.|last3=Nagai|first3=K.|title=Electrically reprogrammable nonvolatile semiconductor memory|journal=IEEE Journal of Solid-State Circuits|date=1972|volume=7|issue=5|pages=369–375|doi=10.1109/JSSC.1972.1052895|issn=0018-9200|bibcode=1972IJSSC...7..369T}}</ref> Flash memory was invented by [[Fujio Masuoka]] at [[Toshiba]] in the early 1980s.<ref>{{cite web |last=Fulford |first=Benjamin |title=Unsung hero |work=Forbes |date=24 June 2002 |access-date=18 March 2008 |url=https://www.forbes.com/global/2002/0624/030.html |url-status=live |archive-url=https://web.archive.org/web/20080303205125/http://www.forbes.com/global/2002/0624/030.html |archive-date=3 March 2008 |df=dmy-all }}</ref><ref>{{patent|US|4531203|Fujio Masuoka}}</ref> Masuoka and colleagues presented the invention of [[NOR flash]] in 1984,<ref>{{cite web |title=Toshiba: Inventor of Flash Memory |url=http://www.flash25.toshiba.com |website=[[Toshiba]] |access-date=20 June 2019}}</ref> and then [[NAND flash]] in 1987.<ref>{{cite conference |chapter=New ultra high density EPROM and flash EEPROM with NAND structure cell |last1=Masuoka |first1=F. |last2=Momodomi |first2=M. |last3=Iwata |first3=Y. |last4=Shirota |first4=R. |title=1987 International Electron Devices Meeting |year=1987 |pages=552–555 |conference=[[International Electron Devices Meeting|IEDM]] 1987 |book-title=Electron Devices Meeting, 1987 International |publisher=[[IEEE]] |df=dmy |doi=10.1109/IEDM.1987.191485}}</ref> Toshiba commercialized NAND flash memory in 1987.<ref name=":0">{{cite web |title=1987: Toshiba Launches NAND Flash |url=https://www.eweek.com/storage/1987-toshiba-launches-nand-flash |website=[[eWeek]] |date=April 11, 2012 |access-date=20 June 2019}}</ref><ref>{{cite web |title=1971: Reusable semiconductor ROM introduced |url=https://www.computerhistory.org/storageengine/reusable-semiconductor-rom-introduced/ |website=[[Computer History Museum]] |access-date=19 June 2019}}</ref><ref name=":2" /> | The term ''memory'' is also often used to refer to [[non-volatile memory]] including [[read-only memory]] (ROM) through modern [[flash memory]]. [[Programmable read-only memory]] (PROM) was invented by [[Wen Tsing Chow]] in 1956, while working for the Arma Division of the American Bosch Arma Corporation.<ref name="Huang2008">{{cite book|author=Han-Way Huang|title=Embedded System Design with C805|url=https://books.google.com/books?id=3zRtCgAAQBAJ&pg=PA22|date=5 December 2008|publisher=Cengage Learning|isbn=978-1-111-81079-5|page=22|url-status=live|archive-url=https://web.archive.org/web/20180427092847/https://books.google.com/books?id=3zRtCgAAQBAJ&pg=PA22|archive-date=27 April 2018}}</ref><ref name="AufaureZimányi2013">{{cite book|author1=Marie-Aude Aufaure|author2=Esteban Zimányi|title=Business Intelligence: Second European Summer School, eBISS 2012, Brussels, Belgium, July 15-21, 2012, Tutorial Lectures|url=https://books.google.com/books?id=7iK5BQAAQBAJ&pg=PA136|date=17 January 2013|publisher=Springer|isbn=978-3-642-36318-4|page=136|url-status=live|archive-url=https://web.archive.org/web/20180427092847/https://books.google.com/books?id=7iK5BQAAQBAJ&pg=PA136|archive-date=27 April 2018}}</ref> In 1967, Dawon Kahng and [[Simon Sze]] of Bell Labs proposed that the [[floating gate]] of a MOS [[semiconductor device]] could be used for the cell of a reprogrammable ROM, which led to [[Dov Frohman]] of [[Intel]] inventing [[EPROM]] (erasable PROM) in 1971.<ref name="computerhistory1971">{{cite web |title=1971: Reusable semiconductor ROM introduced |url=https://www.computerhistory.org/storageengine/reusable-semiconductor-rom-introduced/ |website=[[Computer History Museum]] |access-date=19 June 2019}}</ref> [[EEPROM]] (electrically erasable PROM) was developed by Yasuo Tarui, Yutaka Hayashi and Kiyoko Naga at the [[Electrotechnical Laboratory]] in 1972.<ref>{{cite journal|last1=Tarui|first1=Y.|last2=Hayashi|first2=Y.|last3=Nagai|first3=K.|title=Electrically reprogrammable nonvolatile semiconductor memory|journal=IEEE Journal of Solid-State Circuits|date=1972|volume=7|issue=5|pages=369–375|doi=10.1109/JSSC.1972.1052895|issn=0018-9200|bibcode=1972IJSSC...7..369T}}</ref> Flash memory was invented by [[Fujio Masuoka]] at [[Toshiba]] in the early 1980s.<ref>{{cite web |last=Fulford |first=Benjamin |title=Unsung hero |work=Forbes |date=24 June 2002 |access-date=18 March 2008 |url=https://www.forbes.com/global/2002/0624/030.html |url-status=live |archive-url=https://web.archive.org/web/20080303205125/http://www.forbes.com/global/2002/0624/030.html |archive-date=3 March 2008 |df=dmy-all }}</ref><ref>{{patent|US|4531203|Fujio Masuoka}}</ref> Masuoka and colleagues presented the invention of [[NOR flash]] in 1984,<ref>{{cite web |title=Toshiba: Inventor of Flash Memory |url=http://www.flash25.toshiba.com |website=[[Toshiba]] |access-date=20 June 2019}}</ref> and then [[NAND flash]] in 1987.<ref>{{cite conference |chapter=New ultra high density EPROM and flash EEPROM with NAND structure cell |last1=Masuoka |first1=F. |last2=Momodomi |first2=M. |last3=Iwata |first3=Y. |last4=Shirota |first4=R. |title=1987 International Electron Devices Meeting |year=1987 |pages=552–555 |conference=[[International Electron Devices Meeting|IEDM]] 1987 |book-title=Electron Devices Meeting, 1987 International |publisher=[[IEEE]] |df=dmy |doi=10.1109/IEDM.1987.191485}}</ref> Toshiba commercialized NAND flash memory in 1987.<ref name=":0">{{cite web |title=1987: Toshiba Launches NAND Flash |url=https://www.eweek.com/storage/1987-toshiba-launches-nand-flash |website=[[eWeek]] |date=April 11, 2012 |access-date=20 June 2019}}</ref><ref>{{cite web |title=1971: Reusable semiconductor ROM introduced |url=https://www.computerhistory.org/storageengine/reusable-semiconductor-rom-introduced/ |website=[[Computer History Museum]] |access-date=19 June 2019}}</ref><ref name=":2" /> | ||