What is flash memory? The principle of operation and the device of flash memory. What is flash memory

Today, manufacturers produce several types of flash memory drives: these are cards Compact Flash, SmartMedia, MultiMedia Card, SecureDigital Card, Memory Stick and USB keys.

ATAFlash. The first flash memory drives to hit the market were cards ATA Flash . These drives are made in the form of standard cards. PC Card . In addition to flash memory chips, an ATA controller is installed in them, and during operation they emulate a conventional IDE -disk. The interface of these cards is parallel. Cards ATA Flash not widely used and are currently used extremely rarely.

CompactFlash. Compact Flash Cards (CF ) were offered by the company SanDisk as a more compact and easy-to-use alternative to cards ATA Flash . Therefore, the developers of the standard CF provided the ability to work these cards as devices PC Card or as IDE -devices. In the first case, the cards work as usual PC Card devices and their interface "turns" into a bus PC Card . In the second - how hard IDE disks and their interface works like an ATA bus.

CF cards first appeared in 1994. All cards of this type have a 50-pin parallel interface. By the way, there are maps CF two types - Touré I and Tour II . Touré type cards II two millimeters thicker and appeared only because before the body of Touré cards I did not allow large volume flash memory to be placed inside for the manufacture of capacious media CF . Currently, there is no such need and Touré cards II are gradually leaving the market. Note that in the drives for Touré cards II you can install Tour maps I while the reverse is not possible.

Among flash cards, the undisputed leader in performance was Transcend Ultra Performance 25 x CompactFlash CF Card 256 MB, which can rightfully be considered the benchmark for the rate of modern flash drives. The sequential/random write speed of this flash card reaches 3.6/0.8 MB/s, the read speed is 4.0/3.7 MB/s.

CF speed - cards slow down with increasing volume, which is clearly seen in the example of flash cards512 MB. Doubling the capacity results in a 30% decrease in performance. except for the random write speed, which increased by 2.5 times, it looks rather strange and unexpected.

Speed ​​characteristics CF -cards are also highly dependent on the manufacturer. At Kingston CompactFlash 256 MB - low write speed (sequential / random write - 1.4 / 0.3 MB / s), but in terms of read speed it was the leader (4.4 / 3.8 MB / s). Map PQI Hi-Speed ​​Compact Flash 256 MB showed average performance in both cases: writing - 2.1 / 0.7 MB / s, reading - 3.8 / 3.3 MB / s. Cards SanDisk CompactFlash 256MB and SanDisk CompactFlash 512 MB worked very slowly: writing - 1.1 / 0.2 and 0.9 / 0.5 MB / s, reading - 2.3 / 2.1 and 1.8 / 1.7 MB / s. A map256 MB recorded and read data equally well.

If we compare CF -cards with other types of drives, it turns out that flash memory is not as slow as it is commonly believed! In terms of performance, the fastest samples of flash memory (we will take a card as a reference Transcend Ultra Performance 25x CompactFlash 256 MB) are comparable to Iomega Zip 750 MB, and in terms of sequential write speed they even overtake this drive by more than 1.5 times! Flash outperforms hard drives in sequential write speed CD-RW 2 times, in sequential reading speed - by 10%! Flash memory outperforms MO disks in sequential write speed - 2 times - and random read speed - by 10%, but it lags behind in sequential read speed and random write speed - by 20%. Flash memory lags behind in sequential write speed DVD - disks (when "burning" in 4x mode) - 1.4 times.

Note that if CF - the card is used in a digital camera, then speed is primarily important for it consistent recording - the higher it is, the faster the camera will return to working condition after "capturing" the frame and "resetting" it to the flash card. However, the reading speed CF -cards in this case are also important, though not so critical - the faster the data is read, the faster the camera will work in the footage review mode.

smart media . Card design SmartMedia (SM ) is extremely simple. On the map SM there is no built-in interface controller and, in fact, it is one or two flash memory chips “packed” in a plastic casing. Standard SM was developed by companies Toshiba and Samsung in 1995 Map Interface SM - parallel, 22-pin, but only eight lines are used for data transmission.

MultiMedia card . Multi-Media Cards (MMCs) ) have a 7-pin serial interface that can operate at up to 20 MHz. Inside the plastic case of the card there is a flash memory chip and an MMC interface controller. The MMC standard was proposed in 1997 by companies Hitachi, SanDisk and Siemens.

SecureDigital card . SecureDigital Card (SD ) is the youngest flash card standard: it was developed in 2000 by companies Matsushita, SanDisk and Toshiba. Actually SD - this is a further development of the MMC standard, so MMC cards can be installed in drives SD (the reverse would be false). Interface SD - 9-pin serial-parallel (data can be transmitted one at a time,two or four lines at the same time), operates at a frequency of up to 25 MHz. Cards SD are equipped with a switch to protect their contents from writing (the standard also provides for modification without such a switch).

USB - flash memory. USB flash memory (USB -memory) - a completely new type of flash memory media that appeared on the market in 2001. According to USB form -memory resembles an oblong-shaped keychain, consisting of two halves - a protective cap and the drive itself with USB - connector (one or two flash memory chips are placed inside it and USB controller).

Work with USB -memory is very convenient - it does not require any additional devices. It is enough to have a PC running Windows with idle USB -port to "get" to the contents of this drive in a couple of minutes. In the worst case, you will have to install drivers USB -memory at its best - new USB -device and logical disk will appear in the system automatically. Possibly in the future USB -memory will become the main type of devices for storing and transferring small amounts of data.

As for USB -flash memory, then this is undoubtedly a more convenient solution for data transfer than flash cards - no additional flash drive is required. However, the performance of tested drives of this type is - Transcend JetFlash 256MB and Transcend JetFlashA 256 MB - limited by low interface bandwidth USB 1.1. therefore, their performance in tests for speed was rather modest. If a USB - flash memory to equip with a fast interface USB 2.0, then in terms of "rate of fire" these drives, of course, will not yield to the best flash cards.

It is interesting to note that in terms of sequential write speed, flash memory outperforms Iomega Zip 750 CD-RW discs and MO-carriers and second only to DVD -disks. This once again emphasizes that flash memory developers primarily sought to increase the speed consistent recording, since flash memory was originally designed for use in digital cameras, where this indicator is primarily important.

As a result, we can conclude that flash memory is the undisputed leader in terms of reliability, mobility and power consumption among small and medium-capacity drives, which also has good performance and sufficient volume (flash cards with a capacity of up to 2 GB are already available on the market today). Undoubtedly, this is a very promising type, but their widespread use is still constrained by high prices.

A new word has appeared in everyday life of users - “flash drive”. Most people know for sure that this device is used in digital cameras, and is also designed to transfer movies and music. But this is not a complete list of functions that a flash drive performs. This device is indispensable in the work of any owner of not only a computer, but also all kinds of electronics of the 21st century. The topic of this article is flash memory, its characteristics, types, prices.

Immersed in history

All the giants of the IT industry are rewriting history, establishing their authorship over various inventions. So did the famous American company Intel, which appropriated the invention of flash memory. However, the technology and production of the world's first device belongs to the Japanese giant Toshiba, who presented his discovery to the world back in 1984. The name "flash memory" was also given to the device by the Japanese, and not by chance. The process of erasing information on flash memory is vaguely reminiscent of a flash.

Not even a few years have passed since the invention, and the global giants of the IT industry quickly found a use for the new invention, putting production on the conveyor.

Not all memory is "flash"

A shallow dive into the world of physics reveals that there are several types of memory.

1. RAM, which works on the principle of "electric capacitance". Millions of capacitors, holding the charge in the RAM, are the custodians of information. When the power supply to the device is turned off, the capacitors are discharged, losing information irretrievably.
2. Permanent memory. Information on the carrier is stored by physical or chemical influence. An example is an optical DVD disc, on which information is recorded by burning microscopic holes on the plastic surface with a laser.
3. Conditionally-permanent non-volatile memory. This includes flash memory, magnetic hard drives, floppy disks, videotape, and other media that can hold a magnetic or electrical charge in the absence of a permanent power source.

Flash memory application

For the technologies of the 20th century, the invention was quite sufficient for devices such as a memory card and USB flash drives. But in the 21st century there was a boom in storage media with flash technology. First of all, all mobile phones, tablets, multimedia players and digital devices acquired flash memory. Later, no interactive toy for children could exist without flash memory. Technology didn't stop there. Every day there are new devices equipped with such a wonderful kind of memory. Take at least a flashlight for the policeman. Due to the presence of flash memory in it, the human rights activist can choose the focus and brightness of the beam he needs from the saved settings.

How many device manufacturers

On the market, you can see that the required flash memory is represented by several manufacturers at once. Having almost the same characteristics, the drives differ significantly in price. Is the most expensive purchase going to be the best? Not always! Often the buyer has to overpay for the brand, service and warranty.

There are only a few factories in the world that produce flash memory modules. These modules are snapped up by the giants of the IT industry, who create a beautiful case and sell the drive in their own name. The only difference is the speed of the devices, which depends on the capabilities of the flash memory. Whether the memory is fast or not is decided at the factory.

About prices for flash devices

For anyone who decides to purchase flash memory on their own, the prices on the market may seem strange. Drives of the same volume from two unfamiliar brands have a large difference in cost. What's the matter? There is a set of requirements for flash cards, due to which the manufacturer is obliged to determine the class of the device and mark it on the product case. Often in the store you can find devices on which there is no marking, there is only the logo of the manufacturer. The prices for such memory cards are very low, and the seller claims high performance of the device. Reviews of experts on the pages of respected computer publications recommend refraining from buying unmarked devices, as they are fake or imported into the country illegally.

What you need to know about flash drive labels

Since we are talking about the labeling of drives, when buying, you need to pay attention to the numbers and inscriptions indicated on the case of flash devices.

1. The name of the manufacturer or its logo must be present.
2. The amount of flash memory must be written on the media.
3. The class of the flash device must be indicated on the case. Often manufacturers of USB modules indicate the class on the product packaging, which is not prohibited by law.

On sale you can find flash memory cards without marking, but with a long number, which is printed in small print on the device case. Thus, the manufacturer indicates the batch number by which the buyer can find the device on the Internet and get acquainted with its technical characteristics.

Speed ​​is proportional to price, but not efficiency

The higher the class of flash memory, the higher its write speed, and the higher the price. Is it worth buying the fastest memory?

1. Zero class. Write speed of at least 0.6 Mb per second. You can buy it in stores without seeing the absence of markings. Good for document storage.
2. Classes 2 and 4, with write speeds of 2 and 4 MB per second, respectively, also belong to the office section and are designed for storing and transferring documentation.
3. The sixth and eighth grades with a speed of 6 and 8 Mb per second will be of interest to all buyers working with photos, music, videos. These types of flash memory unlock the potential for multimedia.
4. Class ten and above, including Ultra, show write speeds over 10 MB per second. They are used in working with multimedia, as additional drives for workstations, and used as RAM. Where the speed of reading and writing to the storage medium is critical.

Major brands such as Pretec and Corsair make high-speed devices that can write about 25MB per second, labeling them eighth or tenth grade. The price of modules is very high, but in the IT world, such brands are highly respected by users.

What are the different sizes of flash memory

Another criterion on which the price of a drive depends is the amount of flash memory. Although technology does not stand still, there are still some limits. When it is necessary to change the manufacturing process to increase the amount of memory, a dilemma arises - while maintaining a low price, stop at the achieved result or develop further, looking for wealthy buyers. There has been some lull in the world - customers are offered to buy memory cards with a maximum capacity of 64 gigabytes, with a strong desire, you can become the owner of 128 GB and 256 GB on order, but for this you will have to fork out a lot. It is not known how long it will take for the transition to new technologies and the availability of large-capacity cards on the market, but one thing is known - 64 GB is enough to satisfy any task of an ordinary user.

Wonder beast with a great future

There is another interesting device that uses flash memory in its work - an SSD drive. Along with the volume and speed of recording, the credibility of the manufacturer is critical for the device, which provides the product with a control controller and specialized firmware that controls the entire device. One manufacturer's mistake - and the device can end up in the trash. Everything is complicated, expensive and very serious, but the future belongs to the SSD drive. A direct competitor to computer hard drives that work using magnetism. Resistant to shaking, temperature and silent operation. The day is not far off when magnetic hard drives will share space in the closet with ball mice, giving way to 21st century technology.

How to save money on computer upgrades

Owners of old computers and laptops have often heard from service specialists about the reasons for the low speed of the device. There is not enough RAM, which has long been discontinued. The specialist, looking into the eyes of the owner of the computer, convinces that the only way out of the situation is to buy a modern computer. After 5 years, the same specialist will come and prove once again that there are no solutions other than buying a new computer. This is how the world is built. A world for people who are not interested in knowledge in IT technologies.

RAM flash memory will solve the problem once and for all with minimal cost to the user. It is enough to download a program called Ready Boost from the Internet and study the system requirements for the drive. And only then purchase the necessary flash memory device in the store. Connect a drive to a computer or laptop, run the program and enjoy life. It's so nice to independently increase the performance of your computer without capital investments.

Which brand to prefer

Due to the large number of manufacturers, it is very difficult to decide who to give preference to. Experts recommend making a list of requirements for the drive, and then choosing a brand.

1. The purpose of use allows you to identify the required class of device.
2. Convenience and appearance will tell you how the flash drive should look. For example, for a radio tape recorder in a car, you should pay attention to a small drive so as not to accidentally break it during use.

Having found several required options, ask the seller how issues are resolved when the device breaks down, whether there is a warranty replacement. Flash memory is a consumable and cannot be repaired - you need to know about this before buying. Manufacturers Corsair, Kingston, OCZ, Pretec, Silicon Power, Transcend and IBM deserve positive feedback.

How to protect yourself from losing information from a flash drive

Like any storage medium, a memory card is subject to external factors that all users of flash devices need to be aware of and take care of the safety of their information.

1. Physical failure of modules. Plastic flash cards are very easy to break, but impossible to restore, so when buying, you need to pay attention to metal flash drives or use them very carefully.
2. Moisture can destroy the drive. It is worth paying attention to waterproof media if there is a possibility of water getting on the memory.
3. Infection of flash memory with viruses. Sometimes it is quite difficult to recover information, so you should pay attention to devices that have physical write protection in the form of a switch - this is guaranteed not to give viruses a single chance.

Having found out the principle of operation, types, characteristics, prices and flash memory device, you need to entrust your choice to professionals.

1. Experts recommend giving preference to trusted brands. To do this, just turn to popular sources of information and read reviews about the product. Any self-respecting manufacturer on the Internet has its own website. Here it is worth visiting to get an idea about the company.
2. Do not trust your choice of Chinese fakes, which are offered on the market at a very low price. If there are no other options, be sure to ask the seller to demonstrate the operation of the media before buying. The usual formatting of the device in the Windows environment allows you to determine the health of the flash memory.
3. Preference should be given to fast devices that have the tenth class. Since there are often situations when time is a priority. Then the flash memory will become universal for the user for any device.
4. When buying memory cards for digital technology, you should worry about the ability to read data on a computer. To do this, there are all kinds of adapters that are often offered for purchase along with flash memory.

The performance and lifespan of an SSD is primarily dependent on the NAND flash and controller with firmware. They are the main components of the price of the drive, and it is logical to pay attention to these components when buying. Today we will talk about NAND.

If you wish, you can find the subtleties of the technological process for the production of flash memory on sites specializing in SSD reviews. My article is aimed at a wider readership and has two goals:

1. Lift the veil over the vague specifications published on the websites of SSD manufacturers and stores.
2. Remove questions that you may have when studying the technical characteristics of the memory of different drives and reading reviews written for "iron" geeks.

First, I will illustrate the problem with pictures.

What is indicated in the characteristics of the SSD

NAND specifications published on the official websites of manufacturers and in chain stores do not always contain detailed information. What's more, the terminology varies a lot, and I've compiled data for you on five different drives.

Does this picture tell you anything?

Ok, let's say Yandex.Market is not the most reliable source of information. Let's turn to the manufacturers' websites - has it become easier?

Maybe that will make it clearer?

And if so?

Or is it still better?

Meanwhile, all these drives have the same memory installed! It's hard to believe, especially looking at the last two pictures, isn't it? Having read the entry to the end, you will not only be convinced of this, but you will also read such characteristics as an open book.

NAND Memory Manufacturers

There are far fewer flash memory manufacturers than there are companies selling SSDs under their own brands. Most drives now have memory from:

• Intel/Micron
• Hynix
• Samsung
• Toshiba/SanDisk

Intel and Micron share the same spot on the list for a reason. They manufacture NAND on the same technologies as part of the IMFT joint venture.

At the leading plant in the US state of Utah, the same memory is produced under the brands of these two companies in almost equal proportions. From the factory in Singapore, which is now controlled by Micron, memory can also come off under the brand name of its subsidiary SpecTek.

All SSD manufacturers buy NAND from the companies listed above, so different drives can have virtually the same memory, even if its brand is different.

It would seem that in this situation with memory, everything should be simple. However, there are several types of NAND, which in turn are divided according to different parameters, introducing confusion.

NAND memory types: SLC, MLC and TLC

These are three different types of NAND, the main technological difference between which is the number of bits stored in a memory cell.

SLC is the oldest of the three technologies, and you will hardly find a modern SSD with this NAND. Most drives now have MLC on board, and TLC is the new word in the SSD memory market.

In general, TLC has long been used in USB flash drives, where memory endurance is of no practical importance. New technological processes reduce the cost of a gigabyte of TLC NAND for SSDs, while providing acceptable performance and service life, which is logically interested in all manufacturers.

Interestingly, while the general public is concerned about the limited number of SSD write cycles, as NAND technologies develop, this parameter is only decreasing!

How to determine the specific type of memory in an SSD

Whether you have just purchased a solid state drive or are planning to purchase it, after reading this post, you may have a question posed in the subheading.

No program shows the type of memory. This information can be found in drive reviews, but there is a shorter way, especially when you need to compare several purchase candidates.

On specialized sites you can find SSD databases, and here's an example.

I found the memory specifications of my drives there without any problems, with the exception of the SanDisk P4 (mSATA) installed in the tablet.

Which SSD has the best memory

Let's first go through the main points of the article:

• NAND manufacturers can be counted on the fingers of one hand
• modern solid state drives use two types of NAND: MLC and TLC, which is just gaining momentum
• MLC NAND differs in interfaces: ONFi (Intel, Micron) and Toggle Mode (Samsung, Toshiba)
• ONFi MLC NAND is divided into asynchronous (cheaper and slower) and synchronous (more expensive and faster)
• SSD manufacturers use memory of different interfaces and types, creating a diverse range for any budget
• official specifications rarely contain specific information, but SSD databases allow you to accurately determine the type of NAND

Of course, in such a zoo there cannot be an unequivocal answer to the question posed in the subtitle. Regardless of the brand of the drive, NAND complies with the declared specifications, otherwise it makes no sense for OEMs to buy it (they give their warranty on SSDs).

However ... imagine that summer has pleased you with an unprecedented harvest of strawberries in the country!

It's all juicy and sweet, but you just can't eat that much, so you decide to sell some of the berries you've picked.

Will you keep the best strawberries for yourself or put them up for sale? :)

It can be assumed that NAND manufacturers install the best memory in their drives. Given the limited number of NAND companies, the list of SSD manufacturers is even shorter:

• Crucial (a division of Micron)
• Intel
• Samsung

Again, this is just an assumption, not supported by reliable facts. But would you have acted differently in the place of these companies?

Modern technologies are developing quite quickly, and what yesterday seemed to be the height of perfection, today does not suit us at all. This is especially true for modern types of computer memory. Memory is constantly lacking or the media speed is very low, by modern standards.

Flash memory appeared relatively recently, but having many advantages, it seriously crowds out other types of memory.

Flash memory is a type of solid-state, non-volatile, rewritable memory. Unlike a hard disk, a flash drive has a high read speed, which can reach up to 100 Mb / s, a very small size. It can be easily transported as it connects via a USB port.

It can be used as RAM, but unlike RAM, flash memory stores data when the power is off, autonomously.

Today, flash drives are available on the market with a volume of 256 megabytes to 16 gigabytes. But there are carriers with a large volume.

Additional flash memory features include copy protection, a fingerprint scanner, an encryption module, and much more. Also, if the motherboard supports booting via a USB port, then it can be used as a boot device.

The new flash technologies include UЗ. This media is recognized by the computer as two disks, where data is stored on one, and the computer boots from the second. The advantages of this technology are obvious, you can work on any computer.

The rather small size allows the use of this type of memory very widely. This includes mobile phones, cameras, video cameras, voice recorders and other equipment.

In the description of the technical characteristics of any mobile device, the type of flash memory is indicated, and not by chance, since not all types are compatible. Based on this, you need to choose flash drives that are quite common on the market so as not to have problems with any device.
For some types of flash cards, there are adapters that expand its capabilities.

Existing types of flash memory

Modern flash cards can be divided into six main types.

The first and most common type is Compact Flash (CF), there are two types CF type I and CF type II. It has good speed, capacity and price.
The disadvantages include the size of 42 * 36 * 4 mm. It is quite versatile and is used in many devices.

IBM Microdrive-cheap, but less reliable and consumes more than usual energy, which is the reason for its limitation.

smart media- thin and cheap, but not high abrasion protection.

Multimedia Card (MMC)- small size (24x32x1.4mm), low power consumption, used in miniature devices. The disadvantage is low speed.

SecureDigital (SD) with comparable dimensions with Multimedia Card, it has a larger volume and speed. But more expensive.

memory stick- has good information protection, speed, but not very large capacity.

Today, CompactFlash and SD / MMC are considered the most common, but
in addition to the listed cards, there are other types of flash cards

It is worth choosing a flash card based on your needs, given that the larger the volume and speed, the more expensive the flash card.

What is flash memory? | Flash memory(in English. Flash Memory) or flash drive- a type of solid-state semiconductor non-volatile and rewritable memory.

This type of memory can be read a large number of times within the storage period of information, usually from 10 to 100 years. But memory can be written to only a limited number of times (usually in the region of a million cycles). In general, flash memory is widespread in the world, withstanding about one hundred thousand rewrite cycles, and this is much more than a conventional floppy disk or CD-RW disk can withstand.
Unlike hard disk drives (HDDs), flash memory contains no moving mechanical parts and is therefore considered a more reliable and compact type of storage medium.
So, due to its compactness, relative cheapness and very low power consumption, flash drives are widely used in digital portable equipment - video and photo cameras, voice recorders, MP3 players, PDAs, mobile phones, smartphones and communicators. Moreover, this type of memory is used to store firmware in various equipment (modems, PBXs, scanners, printers, routers).
Recently, flash drives with a USB input (usually they say “flash drive”, USB drive) have become widespread, replacing floppy disks and CDs.
Nowadays, the main disadvantage of devices based on flash drives is a very high price-volume ratio, much higher than that of hard drives by 2-5 times. Therefore, the volume of flash drives is not very large, but work is underway in these areas. Reducing the cost of the technological process and under the influence of competition, many companies have already announced the release of SSDs with a capacity of 512 GB or more. For example, in February 2011, OCZ Technology offered a 1.2TB PCI-Express SSD capable of 10M write cycles.
Modern SSD drives are developed on the basis of multi-channel controllers that provide parallel reading or writing from several flash memory microprocessors at once. As a result, the level of performance increased so much that the bandwidth of the SATA II interface became the limiting factor.

HOW FLASH MEMORY WORKS

A flash drive stores data in an array of floating gate transistors called cells. In conventional devices with single-level cells (in English single-level cell), any of them can "remember" only one bit of data. But some newer chips with multi-level cells (in English multi-level cell or triple-level cell) can "remember" more than one bit. In the latter case, a different electric charge can be used on the floating gate of the transistor.

NOR FLASH MEMORY

This type of flash memory is based on the OR-NOR algorithm (in English NOR), since in a floating gate transistor, too little gate voltage means one.
This type of transistor consists of two gates: floating and control. The first gate is completely isolated and has the ability to hold electrons for up to ten years. The cell also consists of a drain and a source. When voltage is applied to the control gate, an electric field is generated and a so-called tunnel effect occurs. Most of the electrons are transported (tunneled) through the insulator layer and penetrate the floating gate. The charge on the floating gate of the transistor changes the "width" of the drain-source and the conductivity of the channel, which is used in reading.
Writing and reading cells are very different in power consumption: for example, flash drives consume more current when writing than when reading (very little power is consumed).
To delete (erase) data, a sufficiently high negative voltage is applied to the control gate, which leads to the opposite effect (electrons from the floating gate go to the source using the tunnel effect).
In the NOR architecture, there is a need to connect a contact to each transistor, which greatly increases the size of the processor. This problem is solved with the help of the new NAND architecture.

NAND FLASH MEMORY

The NAND architecture is based on the NAND algorithm (in English NAND). The principle of operation is similar to the NOR type, and differs only in the location of the cells and their contacts. It is no longer necessary to connect a contact to each memory cell, so the cost and size of the NAND processor is much less. Due to this architecture, writing and erasing is noticeably faster. However, this technology does not allow access to an arbitrary area or cell, as in NOR.
To achieve maximum density and capacity, the NAND flash drive uses elements with minimal dimensions. Therefore, unlike a NOR drive, the presence of bad cells is allowed (which are blocked and should not be used in the future), which significantly complicates the work with such a flash memory. Moreover, memory segments in NAND are provided with a CRC function to check their integrity.
Currently, NOR and NAND architectures exist in parallel and do not compete with each other in any way, since they have different applications. NOR is used for simple small data storage, NAND for large data storage.

HISTORY OF FLASH DRIVES

Flash memory was first invented in 1984 by Fujio Masuoka, then an engineer at Toshiba. The name "flash" was coined by Fujio's colleague Shoji Ariizumi, as the process of erasing data from memory reminded him of a flash. Fujio presented his development at the International Electron Devices Meeting in San Francisco, California. Intel was interested in this invention and four years later, in 1988, it released the first commercial NOR-type flash processor.
The NAND flash memory architecture was announced a year later by Toshiba in 1989 at the International Solid-State Circuits Conference. The NAND chip had a faster write speed and a smaller circuit area.
At the end of 2010, the leaders in the production of flash drives are Samsung (32% of the market) and Toshiba (17% of the market).
The ONFI (NAND Flash Interface Working Group) group is engaged in the standardization of NAND flash memory processors. This standard is considered to be the ONFI 1.0 specification, which was released on December 28, 2006. ONFI standardization in the production of NAND processors is supported by companies such as Samsung, Toshiba, Intel, Hynix, and others.

FLASH DRIVE SPECIFICATIONS

Currently, the volume of flash drives is measured from kilobytes to hundreds of gigabytes.

In 2005, two companies Toshiba and SanDisk introduced NAND processors with a total capacity of 1 GB, using multi-level cell technology (a transistor can store several bits of data using a different electrical charge on the floating gate).

In September 2006, Samsung introduced a 4 GB chip manufactured using a 40 nm process.

At the end of 2007, Samsung announced the creation of the world's first NAND chip using multi-level cell technology, already made using a 30-nm process with a storage capacity of 8 GB.

In December 2009, Toshiba announced that the 64GB NAND chip was already shipping to customers and mass production began in the first quarter of 2010.

On June 16, 2010, Toshiba introduced the first ever 128 GB processor, consisting of sixteen 8 GB modules.
To increase the amount of flash memory, devices often use a complex array consisting of several processors.

In April 2011, Intel and Micron introduced an 8 GB MLC NAND flash chip manufactured using a 20nm process. The very first 20nm NAND processor has an area of ​​118mm, which is 35-40% smaller than currently available 25nm 8GB chips. Serial production of this chip will begin at the end of 2011.

TYPES AND TYPES OF MEMORY CARDS AND FLASH DRIVES

CF(in English. compact flash): one of the oldest standards for memory types. The first CF flash card was produced by SanDisk Corporation back in 1994. This memory format is very common in our time. Most often it is used in professional video and photo equipment, since due to its large size (43x36x3.3 mm) it is physically problematic to install a Compact Flash slot in mobile phones or MP3 players. In addition, no card can boast of such speeds, volumes and reliability. The maximum volume of Compact Flash has already reached the size of 128 GB, and the data copying speed has been increased to 120 MB / s.

MMC(in English. Multimedia Card): a card in MMC format has a small size - 24x32x1.4 mm. Developed jointly by SanDisk and Siemens. The MMC contains a memory controller and is highly compatible with various types of devices. In most cases, MMC cards are supported by devices with an SD slot.

RS-MMC(in English. Reduced Size Multimedia Card): A memory card that is half the length of a standard MMC card. Its dimensions are 24x18x1.4 mm, and its weight is about 6 grams, all other characteristics and parameters do not differ from MMC. An adapter is required to ensure compatibility with the MMC standard when using RS-MMC cards.

DV-RS-MMC(in English. Dual Voltage Reduced Size Multimedia Card): DV-RS-MMC memory cards with dual power supply (1.8V and 3.3V) feature reduced power consumption, allowing your mobile phone to work a little longer. The dimensions of the card are the same as those of RS-MMC, 24x18x1.4 mm.

MMCmicro: miniature memory card for mobile devices with dimensions of 14x12x1.1 mm. To ensure compatibility with a standard MMC slot, a special adapter must be used.

SD card(in English. Secure Digital Card): Supported by SanDisk, Panasonic, and Toshiba. The SD standard is a further development of the MMC standard. In terms of size and characteristics, SD cards are very similar to MMC, only slightly thicker (32x24x2.1 mm). The main difference from MMC is copyright protection technology: the card has crypto protection against unauthorized copying, increased protection of information from accidental deletion or destruction, and a mechanical write protection switch. Despite the related standards, SD cards cannot be used in devices with an MMC slot.

SDHC(in English. SD High Capacity, high capacity SD): Old SD (SD 1.0, SD 1.1) and new SDHC (SD 2.0) cards and their readers differ in the maximum storage capacity limit, 4 GB for SD and 32 GB for SDHC. SDHC readers are backwards compatible with SD, meaning an SD card will be read in an SDHC reader without problems, but an SDHC card will not be read at all in an SD device. Both options are available in any of three physical size formats (standard, mini and micro).

miniSD(in English. Mini Secure Digital Card): They differ from standard Secure Digital cards in their smaller dimensions of 21.5x20x1.4 mm. An adapter is used to ensure the operation of the card in devices equipped with a conventional SD slot.

microSD(in English. Micro Secure Digital Card): in 2011 they are the most compact removable flash memory devices (11x15x1 mm). They are used primarily in mobile phones, communicators, etc., because, due to their compactness, they can significantly expand the memory of the device without increasing its size. The write protection switch is placed on the microSD-SD adapter. The maximum capacity of a microSDHC card released by SanDisk in 2010 is 32 GB.

Memory Stick Duo: This memory standard was developed and supported by Sony. The body is strong enough. At the moment, this is the most expensive memory of all presented. Memory Stick Duo was developed on the basis of the widely used Memory Stick standard from the same Sony, it is small in size (20x31x1.6 mm).

Memory Stick Micro (M2): This format competes with the microSD format (in terms of size) while retaining the advantages of Sony memory cards.

xD-Picture Card: The card is used in digital cameras manufactured by Olympus, Fujifilm and some others.