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| | From comprehending the wedding party specialist you should consult to identifying ovulation with 100% precision, means that inside the book. To fall pregnant everything must be in the right place so be patient and keep trying. Once you've finally decided to build your own family or to add on to your brood, read on. When you get the monthly 'gift' mark that on the calendar. Research has shown that smoking decreases the amount of eggs in a womanâs ovaries. <br><br>The '19 Kids and Counting' star currently has 19 children, and three grandchildren. There is no "right" time to do so - and if it is causing you anxiety and worry, then you should consult a doctor. Although, there is no basis to this theory, and little is known what causes the issue to begin with. One of the foods you can eliminate from your diet right now to immediately give a boost to your fertility levels are peas. helps you track your period and find out when it is due and so forth. <br><br>This small rise of temperature cannot be felt, but can be measured by a Basal Body Thermometer. Just prior to ovulation, it's doable you'll see an increase in clear and slippery secretions that look rather similar to uncooked egg whites. This is also true for men as smoking and drinking will affects the quality of their sperm. Try to eliminate saturated fat, refined sugar and junk from your diet. In the event you and your baby are living at residence then you ought to be thankful that you might have loving parents who are helping you together with your baby. <br><br>Most of the battle is usually over if one has a male partner and a willing sperm donor. It is estimated that about half of all pregnant women will experience this pregnancy symptom. Learn about how your body works, about what works in your favor and how to read your fertile signs. But even the researchers couldn't believe just how strong an effect this chemical was having. Herbs can help detoxify the liver, which is important to insulin regulation, and stimulate ovary functions. <br><br>The good news is that by reducing your exposure you'll actually get pregnant faster and easier. As a matter of fact, the Office on Women's Health states that for most patients, clomiphene is usually tried first. Try to make out the day or the days when you are ovulating each month. To have a better chance in conceiving a boy, the male partner should consider wearing more loose undergarment and jeans. As ovulation comes near several differences take place in the human body and this consists of an increase in temperature of the body, hormonal differences and changes to the cervical fluid, a lot of women employ a charting procedure to keep track of the differences in order to anticipate the fertile period.<br><br>Should you cherished this information as well as you would like to acquire more details with regards to [http://www.quebec-1759.info/ the fastest way to get pregnant] kindly go to the internet site. |
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| '''Phase-change memory''' (also known as '''PCM''', '''PCME''', '''PRAM''', '''PCRAM''', '''Ovonic Unified Memory''', '''Chalcogenide RAM''' and '''C-RAM''') is a type of [[non-volatile random-access memory]]. PRAMs exploit the unique behavior of [[chalcogenide glass]]. In the older generation of PCM heat produced by the passage of an electric current through a heating element generally made of TiN would be used to either quickly heat and quench the glass, making it [[amorphous solid|amorphous]], or to hold it in its crystallization temperature range for some time, thereby switching it to a [[crystal]]line state. PCM also has the ability to achieve a number of distinct intermediary states, thereby having the ability to hold multiple bits in a single cell, but the difficulties in programming cells in this way has prevented these capabilities from being implemented in other technologies (most notably [[flash memory]]) with the same capability. Newer PCM technology has been trending in a couple different directions. Some groups have been directing a lot of research towards attempting to find viable material alternatives to Ge<sub>2</sub>Sb<sub>2</sub>Te<sub>5</sub> (GST), with mixed success, while others have developed the idea of using a GeTe - Sb<sub>2</sub>Te<sub>3</sub> [[superlattice]] in order to achieve non thermal phase changes by simply changing the coordination state of the Germanium atoms with a laser pulse, and this new Interfacial phase change memory (IPCM) has had many successes and continues to be the site of much active research.<ref>{{cite journal|last=Simpson|first=R.E.|coauthors=P. Fons, A. V. Kolobov, T. Fukaya, M. Krbal, T. Yagi & J. Tominaga|title=Interfacial phase-change memory|journal=Nature nanotechnology|date=July 2011|accessdate=9 November 2012}}</ref>
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| [[Leon Chua]] has argued that all 2-terminal non-volatile memory devices including phase change memory should be considered [[memristors]].<ref name="chua11">{{citation |last=Chua |first=L. O. |year=2011 |title=Resistance switching memories are memristors |journal=Applied Physics A |volume=102 |issue=4 |pages=765–783 |doi=10.1007/s00339-011-6264-9}}</ref> Stan Williams of [[HP Labs]] has also argued that phase change memory should be considered to be a [[memristor]].<ref name="Mellor2011">{{Citation |last=Mellor |first=Chris |date=10 October 2011|title=HP and Hynix to produce the memristor goods by 2013|url=http://www.theregister.co.uk/2011/10/10/memristor_in_18_months/ |work=The Register |accessdate=2012-03-07}}</ref> Such claims, however, seem not to be justified given that the [[memristor]] theory is in itself open to question.<ref name="Meuffels_2012">{{citation |last=Meuffels |first=P. |last2=Soni |first2=R. |year=2012 |journal=[[arXiv]] |title=Fundamental Issues and Problems in the Realization of Memristors |arxiv=1207.7319 |bibcode = 2012arXiv1207.7319M }}</ref><ref name="DiVentra_2013">{{cite journal|last=Di Ventra|first=Massimiliano|coauthors=Pershin, Yuriy V.|title=On the physical properties of memristive, memcapacitive and meminductive systems|journal=Nanotechnology|year=2013|volume=24|issue=25|doi=10.1088/0957-4484/24/25/255201|url=http://iopscience.iop.org/0957-4484/24/25/255201/|arxiv = 1302.7063 |bibcode = 2013Nanot..24y5201D }}</ref>
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| ==Background==
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| In the 1960s, [[Stanford R. Ovshinsky]] of Energy Conversion Devices first explored the properties of chalcogenide glasses as a potential memory technology. In 1969, Charles Sie published a dissertation,<ref>"Memory Devices Using Bistable Resistivity in Amorphous As-Te-Ge Films" C. H. Sie, PhD dissertation, Iowa State University, Proquest/UMI publication #69-20670, January 1969</ref><ref>"Chalcogenide Glass Bistable Resistivity Memory" C.H. Sie, A.V. Pohm, P. Uttecht, A. Kao and R. Agrawal, IEEE, MAG-6, 592, September 1970</ref> at Iowa State University that both described and demonstrated the feasibility of a phase change memory device by integrating chalcogenide film with a [[diode]] array. A cinematographic study in 1970 established that the phase change memory mechanism in chalcogenide glass involves electric-field-induced crystalline filament growth.<ref>"Electric-Field Induced Filament Formation in As-Te-Ge Semiconductor" C.H. Sie, R. Uttecht, H. Stevenson, J. D. Griener and K. Raghavan , Journal of Non-Crystalline Solids, 2, 358-370,1970</ref><ref>{{cite web|url=http://www.youtube.com/watch?v=0bgVsOk17vw |title=A Cinematic Study of Mechanisms of Phase Change Memory |publisher=YouTube |date=2012-06-21 |accessdate=2013-09-17}}</ref> In the September 1970 issue of ''[[Electronics (magazine)|Electronics]]'', [[Gordon Moore]] — co-founder of [[Intel]] — published an article on the technology. However, material quality and power consumption issues prevented commercialization of the technology. More recently, interest and research have resumed as flash and [[dynamic random access memory|DRAM]] memory technologies are expected to encounter scaling difficulties as chip [[lithography]] shrinks.<ref>{{cite web|url=http://features.techworld.com/storage/3211959/is-nand-flash-memory-a-dying-technology/|publisher=Techworld|title=Is NAND flash memory a dying technology?|accessdate= 2010-02-04}}</ref>
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| The crystalline and amorphous states of chalcogenide glass have dramatically different [[resistivity|electrical resistivity]]. The amorphous, high resistance state represents a [[Binary numeral system|binary]] 1, while the crystalline, low resistance state represents a 0.{{citation needed|date=July 2012}} Chalcogenide is the same material used in re-writable optical media (such as [[CD-RW]] and [[DVD-RW]]). In those instances, the material's optical properties are manipulated, rather than its electrical resistivity, as chalcogenide's [[refractive index]] also changes with the state of the material.
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| Although PRAM has not yet reached the commercialization stage for consumer electronic devices, nearly all prototype devices make use of a [[chalcogenide]] alloy of [[germanium]], [[antimony]] and [[tellurium]] ([[GeSbTe]]) called GST. The [[stoichiometry]] or Ge:Sb:Te element ratio is 2:2:5. When GST is heated to a high temperature (over 600°C), its chalcogenide crystallinity is lost. Once cooled, it is frozen into an amorphous glass-like state and its [[electrical resistance]] is high. By heating the chalcogenide to a temperature above its [[crystallization|crystallization point]], but below the [[melting point]], it will transform into a crystalline state with a much lower resistance. The time to complete this phase transition is temperature-dependent. Cooler portions of the chalcogenide take longer to crystallize, and overheated portions may be remelted. A crystallization time scale on the order of 100 ns is commonly used.<ref>H. Horii et al.,2003 Symposium on VLSI Technology, 177-178 (2003).</ref> This is longer than conventional volatile memory devices like modern [[DRAM]], which have a switching time on the order of two nanoseconds. However, a January 2006 Samsung Electronics patent application indicates PRAM may achieve switching times as fast as five nanoseconds. | |
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| A more recent advance pioneered by [[Intel]] and [[ST Microelectronics]] allows the material state to be more carefully controlled, allowing it to be transformed into one of four distinct states; the previous amorphic or crystalline states, along with two new partially crystalline ones. Each of these states has different electrical properties that can be measured during reads, allowing a single cell to represent two bits, doubling memory density.<ref name=review>[http://www.technologyreview.com/Infotech/20148/ A Memory Breakthrough], Kate Greene, Technology Review, 04-Feb-2008</ref>
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| [[File:PRAM cell structure.svg|thumb|300px|right|A cross-section of two PRAM memory cells. One cell is in low resistance crystalline state, the other in high resistance amorphous state.]]
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| ==PRAM vs. Flash==
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| It is the switching time and inherent scalability<ref name=scaling>[http://pubs.acs.org/doi/abs/10.1021/nl902777z], Toward the Ultimate Limit of Phase Change in Ge2Sb2Te5</ref> that makes PRAM most appealing. PRAM's temperature sensitivity is perhaps its most notable drawback, one that may require changes in the production process of manufacturers incorporating the technology.
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| Flash memory works by modulating charge ([[electron]]s) stored within the gate of a [[MOSFET|MOS transistor]]. The gate is constructed with a special "stack" designed to trap charges (either on a floating gate or in [[charge trap flash|insulator "traps"]]). The presence of charge within the gate shifts the transistor's [[threshold voltage]], <math>\,V_{th}</math> higher or lower, corresponding to a 1 to 0, for instance. Changing the bit's state requires removing the accumulated charge, which demands a relatively large voltage to "suck" the electrons off the floating gate. This burst of voltage is provided by a [[charge pump]], which takes some time to build up power. General write times for common Flash devices are on the order of 0.1ms (for a block of data), about 10,000 times the typical 10 ns read time, for SRAM for example (for a byte).
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| PRAM can offer much higher performance in applications where writing quickly is important, both because the memory element can be switched more quickly, and also because single bits may be changed to either 1 or 0 without needing to first erase an entire block of cells. PRAM's high performance, thousands of times faster than conventional hard drives, makes it particularly interesting in nonvolatile memory roles that are currently performance-limited by memory access timing.
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| In addition, with Flash, each burst of voltage across the cell causes degradation. As the size of the cells decreases, damage from programming grows worse because the voltage necessary to program the device does not scale with the lithography. Most flash devices are rated for, currently, only 5,000 writes per sector, and many [[flash controller]]s perform [[wear leveling]] to spread writes across many physical sectors.
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| PRAM devices also degrade with use, for different reasons than Flash, but degrade much more slowly. A PRAM device may endure around 100 million write cycles.<ref name=DailyTech>[http://dailytech.com/Article.aspx?newsid=6371 Intel to Sample Phase Change Memory This Year]</ref> PRAM lifetime is limited by mechanisms such as degradation due to GST thermal expansion during programming, metal (and other material) migration, and other mechanisms still unknown.
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| Flash parts can be programmed before being soldered on to a [[Printed circuit board|board]], or even purchased pre-programmed. The contents of a PRAM, however, are lost because of the high temperatures needed to solder the device to a board (see [[reflow soldering]] or [[wave soldering]]). This is made worse by the recent drive to [[Restriction of Hazardous Substances Directive|lead-free]] manufacturing requiring higher soldering temperatures. The manufacturer using PRAM parts must provide a mechanism to program the PRAM "in-system" after it has been soldered in place.
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| The special gates used in Flash memory "leak" charge (electrons) over time, causing corruption and loss of data. The resistivity of the memory element in PRAM is more stable; at the normal working temperature of 85°C, it is projected to retain data for 300 years.<ref>Pirovano, A. Redaelli, A. Pellizzer, F. Ottogalli, F. Tosi, M. Ielmini, D. Lacaita, A.L. Bez, R. Reliability study of phase-change nonvolatile memories. IEEE Transactions on Device and Materials Reliability. Sept. 2004, vol 4, issue 3, pp. 422–427. ISSN 1530-4388.</ref>
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| By carefully modulating the amount of charge stored on the gate, Flash devices can store multiple (usually two) bits in each physical cell. In effect, this doubles the memory density, reducing cost. PRAM devices originally stored only a single bit in each cell, but Intel's recent advances have removed this problem.
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| Because Flash devices trap electrons to store information, they are susceptible to data corruption from radiation, making them unsuitable for many space and military applications. PRAM exhibits higher resistance to radiation.
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| PRAM cell selectors can use various devices: [[diode]]s, [[Bipolar junction transistor|BJTs]] and [[MOSFET]]s. Using a diode or a BJT provides the greatest amount of current for a given cell size. However, the concern with using a diode stems from parasitic currents to neighboring cells, as well as a higher voltage requirement, resulting in higher power consumption. The chalcogenide resistance being a necessarily larger resistance than the diode entails that the operating voltage must exceed 1 V by a wide margin to guarantee adequate forward bias current from the diode. Perhaps the most severe consequence of using a diode-selected array, in particular for large arrays, is the total reverse bias leakage current from the unselected bit lines. In transistor-selected arrays, only the selected bit lines contribute reverse bias leakage current. The difference in leakage current is several orders of magnitude. A further concern with scaling below 40 nm is the effect of discrete dopants as the p-n junction width scales down.
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| ==2000 and later==
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| In August 2004, Nanochip licensed PRAM technology for use in [[Microelectromechanical systems|MEMS]] (micro-electric-mechanical-systems) probe storage devices. These devices are not solid state. Instead, a very small platter coated in chalcogenide is dragged beneath many (thousands or even millions) of electrical probes that can read and write the chalcogenide. Hewlett-Packard's micro-mover technology can accurately position the platter to 3 nm so densities of more than 1 Tbit (125 GB) per square inch will be possible if the technology can be perfected. The basic idea is to reduce the amount of wiring needed on-chip; instead of wiring every cell, the cells are placed closer together and read by current passing through the MEMS probes, acting like wires. This approach bears much resemblance to IBM's [[IBM Millipede|Millipede]] technology.
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| ===Samsung 46.7 nm cell===
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| In September 2006, [[Samsung]] announced a prototype 512 Mb (64 MB) device using diode switches.<ref name=samsung>[http://www.samsung.com/us/business/semiconductor/newsView.do?news_id=766.0 SAMSUNG Introduces the Next Generation of Nonvolatile Memory - PRAM]</ref> The announcement was something of a surprise, and it was especially notable for its fairly high density. The prototype featured a cell size of only 46.7 nm, smaller than commercial Flash devices available at the time. Although Flash devices of higher ''capacity'' were available (64 Gb, or 8 GB, was just coming to market), other technologies competing to replace Flash in general offered lower densities (larger cell sizes). The only production [[MRAM]] and [[FeRAM]] devices are only 4 Mb, for example. The high density of Samsung's prototype PRAM device suggested it could be a viable Flash competitor, and not limited to niche roles as other devices have been. PRAM appeared to be particularly attractive as a potential replacement for NOR Flash, where device capacities typically lag behind those of [[NAND flash memory|NAND]] Flash devices. (State-of-the-art capacities on NAND passed 512 Mb some time ago.) NOR Flash offers similar densities to Samsung's PRAM prototype and already offers bit addressability (unlike NAND where memory is accessed in banks of many bytes at a time).
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| ===Intel device===
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| Samsung's announcement was followed by one from [[Intel]] and [[STMicroelectronics]], who demonstrated their own PRAM devices at the 2006 [[Intel Developer Forum]] in October.<ref>[http://www.eweek.com/article2/0,1895,2021822,00.asp Intel Previews Potential Replacement for Flash]</ref> They showed a 128 Mb part that began manufacture at STMicroelectronics's research lab in Agrate, Italy. Intel stated that the devices were strictly proof-of-concept.
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| ===BAE device===
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| PRAM is also a promising technology in the military and aerospace industries where radiation effects make the use of standard non-volatile memories such as Flash impractical. PRAM memory devices have been introduced by [[BAE Systems]], referred to as C-RAM, claiming excellent radiation tolerance ([[rad-hard]]) and [[latchup]] immunity. In addition, BAE claims a write cycle endurance of 10<sup>8</sup>, which will allow it to be a contender for replacing [[Programmable read-only memory|PROM]]s and [[EEPROM]]s in space systems.
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| ===Multi-level cell===
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| In February 2008, Intel and STMicroelectronics revealed the first multilevel ([[Multi-level Cell|MLC]]) PRAM array prototype. The prototype stored two logical bits in each physical cell, in effect 256 Mb of memory stored in a 128 Mb physical array. This means that instead of the normal two states—fully amorphous and fully crystalline—an additional two distinct intermediate states represent different degrees of partial crystallization, allowing for twice as many bits to be stored in the same physical area.<ref name=review/>
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| ===Intel 90 nm device===
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| Also in February 2008, Intel and STMicroelectronics shipped prototype samples of their first PRAM product to customers. The 90 nm, 128 Mb (16 MB) product was called Alverstone.<ref name="numonyx_sample">{{cite web|title=Intel, STMicroelectronics Deliver Industry's First Phase Change Memory Prototypes|publisher=Numonyx|date=2008-02-06|url=http://www.numonyx.com/en-US/About/PressRoom/Releases/Pages/IntelSTDeliverFirstPCMPrototypes.aspx|accessdate=2008-08-15 |archiveurl = http://web.archive.org/web/20080609215913/http://www.numonyx.com/en-US/About/PressRoom/Releases/Pages/IntelSTDeliverFirstPCMPrototypes.aspx <!-- Bot retrieved archive --> |archivedate = 2008-06-09}}</ref>
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| In June 2009, Samsung and Numonyx B.V. announced a collaborative effort in the development of PRAM market tailored hardware products.<ref name="Samsung Electronics and Numonyx Join Forces on Phase Change Memory">{{cite web|title=Samsung Electronics and Numonyx Join Forces on Phase Change Memory| publisher=Samsung|date=2009-06-23|url=http://www.samsung.com/us/business/semiconductor/newsView.do?news_id=1023;articleID=1023}}</ref>
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| In April 2010,<ref name="eetimes article">{{cite web|title=Samsung to ship MCP with phase-change| publisher=EE Times|date=2010-04-28|url=http://www.eetimes.com/showArticle.jhtml;jsessionid=AZ0IF3RVEBPQVQE1GHPSKHWATMY32JVN?articleID=224700051|accessdate=2010-05-03}}</ref> Numonyx announced the Omneo line of 128-Mbit NOR-compatible phase-change memories. Samsung announced shipment of 512 Mb phase-change RAM (PRAM) in a multi-chip package (MCP) for use in mobile handsets by Fall 2010.
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| In June 2011,<ref name="engadget article">{{cite web|title=IBM develops 'instantaneous' memory, 100x faster than flash| publisher=engadget|date=2011-06-30|url=http://www.engadget.com/2011/06/30/embargo-ibm-develops-instantaneous-memory-100x-faster-than-fl/|accessdate=2011-06-30}}</ref> IBM announced that they had created stable, reliable, multi-bit phase change memory with high performance and stability.
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| ===Alumnium/antimony===
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| Phase-change memory devices based on germanium, antimony and tellurium present manufacturing challenges, since etching and polishing of the material with chalcogens can change the material’s composition. Materials based on Al and Sb are more thermally stable than Ge-Sb-Te. Al50Sb50 has three distinct resistance levels, offering the potential to store three bits of data in two cells as opposed to three.<ref>{{cite web|url=http://www.kurzweilai.net/will-phase-change-memory-replace-flash-memory |title=Will phase-change memory replace flash memory? |publisher=KurzweilAI |date= |accessdate=2013-09-17}}</ref><ref>{{cite doi|10.1063/1.4818662}}</ref>
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| ==Challenges==
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| The greatest challenge for phase-change memory has been the requirement of high programming current density (>10<sup>7</sup> A/cm², compared to 10<sup>5</sup>-10<sup>6</sup> A/cm² for a typical transistor or diode) in the active volume highly unlikely. {{citation needed|date=June 2012}}{{Copy edit-inline|for=Missing words|date=May 2013}} This has led to active areas that are much smaller than the driving transistor area. The discrepancy has forced phase-change memory structures to package the heater and sometimes the phase-change material itself in sublithographic dimensions. This is a process cost disadvantage compared to Flash.
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| The contact between the hot phase-change region and the adjacent dielectric is another fundamental concern. The dielectric may begin to leak current at higher temperature, or may lose adhesion when expanding at a different rate from the phase-change material.
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| Phase-change memory is susceptible to a fundamental tradeoff of unintended vs. intended phase-change. This stems primarily from the fact that phase-change is a thermally driven process rather than an electronic process. Thermal conditions that allow for fast crystallization should not be too similar to standby conditions, e.g. room temperature. Otherwise data retention cannot be sustained. With the proper activation energy for crystallization it is possible to have fast crystallization at programming conditions while having very slow crystallization at normal conditions.
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| Probably the biggest challenge for phase change memory is its long-term resistance and threshold voltage drift.<ref>D. Ielmini et al., IEEE Trans. Electron Dev. vol. 54, 308-315 (2007).</ref> The resistance of the amorphous state slowly increases according to a power law (~t<sup>0.1</sup>). This severely limits the ability for multilevel operation (a lower intermediate state would be confused with a higher intermediate state at a later time) and could also jeopardize standard two-state operation if the threshold voltage increases beyond the design value.
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| In April 2010, Numonyx released its [http://www.numonyx.com/en-US/AdCampaigns/EMB/Pages/Omneo.aspx Omneo]{{Dead link|date=April 2011}} line of parallel and serial interface 128 Mb NOR-Flash replacement PRAM chips. Although the NOR flash chips they intended to replace operated in the -40-85 °C range, the PRAM chips operated in the 0-70°C range, indicating a smaller operating window compared to NOR flash. This is likely due to the use of highly temperature sensitive p-n junctions to provide the high currents needed for programming.
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| ==Timeline==
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| *'''January 1955''': Kolomiets and Gorunova revealed semiconducting properties of [[chalcogenide glass]]es.<ref>[http://onlinelibrary.wiley.com/doi/10.1002/pssb.19640070202/abstract Physica Status Solidi, vol.7, p.359, 1964.]</ref><ref>[http://onlinelibrary.wiley.com/doi/10.1002/pssb.19640070302/abstract Physica Status Solidi, vol.7, p.713, 1964.]</ref>
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| *'''September 1966''': [[Stanford Ovshinsky]] files first patent on phase change technology
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| *'''January 1969''': Charles H. Sie published a dissertation at Iowa State University on chalcogenide phase change memory device
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| *'''June 1969''': US Patent 3,448,302 (Shanefield) licensed to Ovshinsky claims first reliable operation of PRAM device
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| *'''September 1970''': [[Gordon Moore]] publishes research in [[Electronics Magazine]]
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| *'''June 1999''': Ovonyx joint venture is formed to commercialize PRAM technology
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| *'''November 1999''': Lockheed Martin works with Ovonyx on PRAM for space applications
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| *'''February 2000''': Intel invests in Ovonyx, licenses technology
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| *'''December 2000''': ST Microelectronics licenses PRAM technology from Ovonyx
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| *'''March 2002''': Macronix files a patent application for transistor-less PRAM
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| *'''July 2003''': Samsung begins work on PRAM technology
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| *'''2003 through 2005''': PRAM-related patent applications filed by Toshiba, Hitachi, Macronix, Renesas, Elpida, Sony, Matsushita, Mitsubishi, Infineon and more
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| *'''August 2004''': Nanochip licenses PRAM technology from Ovonyx for use in MEMS probe storage
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| *'''August 2004''': Samsung announces successful 64 Mbit PRAM array
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| *'''February 2005''': Elpida licenses PRAM technology from Ovonyx
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| *'''September 2005''': Samsung announces successful 256 Mbit PRAM array, touts 400 µA programming current
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| *'''October 2005''': Intel increases investment in Ovonyx
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| *'''December 2005'''; Hitachi and Renesas announce 1.5 V PRAM with 100 µA programming current
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| *'''December 2005''': Samsung licenses PRAM technology from Ovonyx
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| *'''July 2006''': BAE Systems begins selling the first commercial PRAM chip
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| *'''September 2006''': Samsung announces 512 Mbit PRAM device
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| *'''October 2006''': Intel and STMicroelectronics show a 128 Mbit PRAM chip
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| *'''December 2006''': IBM Research Labs demonstrate a prototype 3 by 20 nanometers<ref>[http://www.techtree.com/India/News/Phase_Change_Memory_to_Replace_Flash/551-77782-581.html Phase Change to Replace Flash?]</ref>
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| *'''January 2007''': [[Qimonda]] licenses PRAM technology from Ovonyx
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| *'''April 2007''': Intel's chief technology officer Justin Rattner is set to give the first public demonstration of the company's PRAM (phase-change RAM) technology <ref>[http://www.techworld.com/storage/news/index.cfm?newsid=8552 Techworld.com - Intel set for first public demo of PRAM]</ref>
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| *'''October 2007''': [[Hynix]] begins pursuing PRAM by [http://www.digitimes.com/news/a20071001PR200.html licensing Ovonyx' technology]
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| *'''February 2008''': Intel and STMicroelectronics announce four-state MLC PRAM<ref name=review/> and begin shipping samples to customers.<ref name="numonyx_sample" />
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| *'''December 2008''': Numonyx announces mass production 128 Mbit PRAM device to selected customer.
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| *'''June 2009''': Samsung's phase change RAM will go into mass production starting in June<ref>[http://www.engadget.com/2009/05/05/samsungs-pram-chips-go-into-mass-production-in-june/ Engadget Samsung PRAM chips go into mass production]</ref>
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| *'''September 2009''': Samsung announces mass production start of 512 Mbit PRAM device<ref>[http://www.eetimessupplynetwork.com/220100470?cid=RSSfeed_eetsn_eetsnRSS Samsung moves phase-change memory to production]</ref>
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| *'''October 2009''': Intel and Numonyx announce they have found a way to stack phase change memory arrays on one die<ref>[http://www.intel.com/pressroom/archive/releases/2009/20091028corp.htm Intel and Numonyx Achieve Research Milestone with Stacked, Cross Point Phase Change Memory Technology]</ref>
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| *'''December 2009''': Numonyx announces 1 Gb 45 nm product<ref>[http://investors.micron.com/releasedetail.cfm?ReleaseID=467227 Numonyx to Present Phase Change Memory Research Results at Leading Technology Industry Conference]</ref>
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| *'''April 2010''': Numonyx releases Omneo PRAM Series (P8P and P5Q), both in 90 nm.<ref>[http://numonyx.com/en-US/About/PressRoom/Releases/Pages/NewPCMDevices.aspx Numonyx new PRAM devices]</ref>
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| *'''April 2010''': Samsung releases 512Mbit PRAM with 65 nm process, in Multi-Chip-Package.<ref>[http://www.samsung.com/us/aboutsamsung/news/newsIrRead.do?news_ctgry=irnewsrelease&page=1&news_seq=18828&rdoPeriod=ALL&from_dt=&to_dt=&search_keyword= Samsung Ships Industry’s First MCP with a PRAM chip for handsets]</ref>
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| *'''February 2011''': Samsung presented 58 nm 1.8V 1Gb PRAM.<ref>[http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F5740653%2F5746170%2F05746415.pdf%3Farnumber%3D5746415&authDecision=-203 A 58nm 1.8V 1Gb PRAM with 6.4MB/s program BW]</ref>
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| *'''February 2012''': Samsung presented 20 nm 1.8V 8Gb PRAM<ref>[http://www.miracd.com/ISSCC2012/WebAP/PDF/AP_Full.pdf A 20nm 1.8V 8Gb PRAM with 40MB/s Program Bandwidth]</ref>
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| *'''July 2012''': Micron announces availability of Phase-Change Memory for mobile devices - the first PRAM solution in volume production<ref>[http://investors.micron.com/releasedetail.cfm?ReleaseID=692563 Micron Announces Availability of Phase Change Memory for Mobile Devices]</ref>
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| *'''January 2014''': Micron withdraws all PCM parts from the market.<ref>{{cite web |url=http://www.theregister.co.uk/2014/01/14/phase_change_micron_drops_phase_change_memory_products/ |title=Micron: Hot DRAM. We don't need no steenkin' PCM |last1=Mellor |first1=Chris |date=14 January 2014 |website=www.theregister.co.uk |publisher=The Register |accessdate=14 January 2014}}</ref>
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| ==References==
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| {{reflist|colwidth=30em}}
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| ==External links==
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| *[http://www.numonyx.com/ Numonyx]
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| *[http://ovonyx.com/ Ovonyx, Inc.]
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| *[http://www.ovonic.com Energy Conversion Devices, Inc.]
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| *[http://www.hitachi.com/New/cnews/051213.html Hitachi/Renesas Low-Power PRAM]
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| *[http://www.hp.com/hpinfo/abouthp/iplicensing/ars.html Hewlett-Packard Probe Storage]
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| *[http://www.epcos.org/library/library2009.htm European\Phase Change and Ovonics Symposium]
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| *[http://www.eis.na.baesystems.com/news_room/new_product_release/c_ram.htm BAE C-RAM Radiation-Hardened NVM press release]
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| *[http://www.eis.na.baesystems.com/sse/memory_cram.htm BAE C-RAM Radiation-Hardened NVM data sheet]
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| *[http://numonyx.com/en-US/Community/TechTalk/Pages/VideoDetail.aspx?ContentId=1 Introduction to PCM]{{dead link|date=July 2012}} by Numonyx (video)
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| {{Emerging technologies}}
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| {{DEFAULTSORT:Phase-Change Memory}}
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| [[Category:Types of RAM]]
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| [[Category:Non-volatile memory]]
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| [[Category:Emerging technologies]]
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