Non-volatile random-access memory: Difference between revisions

Revision as of 15:57, 28 May 2020

Revision as of 13:50, 10 June 2020

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{{Memory types}}

{{short description|Type of computer memory}}

'''Non-volatile random-access memory''' ('''NVRAM''') is [[random-access memory]] that retains data without applied power. This is in contrast to [[dynamic random-access memory]] (DRAM) and [[static random-access memory]] (SRAM), which both maintain data only for as long as power is applied, or such forms of memory as magnetic tape, which cannot be randomly accessed but which retains data indefinitely without electric power.

[[Read-only memory]] devices can be used to store system [[firmware]] in [[embedded system]]s such as an automotive ignition system control or home appliance. They are also used to hold the initial processor instructions required to [[Bootstrapping |bootstrap]] a computer system. Read-write memory can be used to store calibration constants, passwords, or setup information, and may be integrated into a [[microcontroller]].

If the main memory of a computer system were non-volatile, it would greatly reduce the time required to start a system after a power interruption. Current existing types of semiconductor non-volatile memory have limitations in memory size, power consumption, or operating life that make them impractical for main memory. Development is going on for the use of non-volatile memory chips as a system's main memory, as [[persistent memory]]. Known as [[NVDIMM#Types|NVDIMM-P]], it is expected to be released in 2020.<ref>{{cite press release|url=https://www.jedec.org/news/pressreleases/jedec-ddr5-nvdimm-p-standards-under-development|title=JEDEC DDR5 & NVDIMM-P Standards Under Development|date=2017-03-30|publisher=[[JEDEC]]}}</ref><ref>{{cite press release|url=https://www.jedec.org/news/pressreleases/jedec-hold-workshops-ddr5-lpddr5-nvdimm-p-standards|title=JEDEC to Hold Workshops for DDR5, LPDDR5 & NVDIMM-P Standards|date=2019-09-05|publisher=JEDEC}}</ref>

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Another solid-state technology to see more than purely experimental development is [[Phase-change RAM]], or PRAM. PRAM is based on the same storage mechanism as writable [[Compact Disk|CDs]] and [[DVD]]s, but reads them based on their changes in electrical resistance rather than changes in their optical properties. Considered a "dark horse" for some time, in 2006 [[Samsung]] announced the availability of a 512 Mbit part, considerably higher capacity than either MRAM or FeRAM. The areal density of these parts appears to be even higher than modern flash devices, the lower overall storage being due to the lack of multi-bit encoding. This announcement was followed by one from [[Intel]] and [[STMicroelectronics]], who demonstrated their own PRAM devices at the 2006 [[Intel Developer Forum]] in October.

[[Intel]] and [[STMicroelectronics]] are now selling PRAM based devices to consumers, under the names [[3D XPoint]] Optane, and QuantX.<ref>{{cite web |url=https://pcper.com/2017/06/how-3d-xpoint-phase-change-memory-works/}}</ref>.

===Millipede memory===

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{{DEFAULTSORT:Non-Volatile Random-Access Memory}}

[[Category:Non-volatile random-access memory| ]]

[[Category:Non-volatile memory]]

[[Category:Computer memory]]