Flash memory is a type of long-lasting memory for computers in which the contents can be reprogrammed or electrically erased. Compared to Electrically Erasable Programmable Read Only Memory, operations on it can be performed in blocks that are located in different places. Flash memory costs much less than EEPROM, which is why it has become the dominant technology. Particularly in situations where stable and long-term data storage is required. Its use is allowed in a wide variety of cases: in digital audio players, photo and video cameras, mobile phones and smartphones, where there are special Android applications for the memory card. In addition, it is also used in USB flash drives, traditionally used to save information and transfer it between computers. It has gained some fame in the world of gamers, where it is often used to store game progress data.

general description

Flash memory is a type that is capable of storing information on its board for a long time without using power. In addition, we can note the highest data access speed, as well as better resistance to kinetic shock in comparison with hard drives. It is thanks to these characteristics that it has become so popular for devices powered by batteries and rechargeable batteries. Another undeniable advantage is that when flash memory is compressed into a solid card, it is almost impossible to destroy it by any standard physical means, so it can withstand boiling water and high pressure.

Low-level data access

The way to access data residing in flash memory is very different from that of conventional types. Low-level access is provided through the driver. Conventional RAM immediately responds to calls to read and write information, returning the results of such operations, but the design of flash memory is such that it takes time to think about it.

Design and principle of operation

At the moment, flash memory is widespread, which is created on single-transistor elements with a “floating” gate. This makes it possible to provide greater data storage density compared to dynamic RAM, which requires a pair of transistors and a capacitor element. At the moment, the market is replete with various technologies for constructing basic elements for this type of media, which are developed by leading manufacturers. They are distinguished by the number of layers, methods of recording and erasing information, as well as the organization of the structure, which is usually indicated in the name.

Currently, there are a couple of types of chips that are most common: NOR and NAND. In both, the storage transistors are connected to the bit buses - in parallel and in series, respectively. The first type has fairly large cell sizes and allows for fast random access, allowing programs to be executed directly from memory. The second is characterized by smaller cell sizes, as well as fast sequential access, which is much more convenient when it is necessary to build block-type devices where large amounts of information will be stored.

In most portable devices, the SSD uses the NOR memory type. However, devices with a USB interface are becoming increasingly popular. They use NAND memory. Gradually it displaces the first one.

The main problem is fragility

The first samples of mass-produced flash drives did not please users with high speeds. However, now the speed of writing and reading information is at such a level that you can watch a full-length movie or run an operating system on your computer. A number of manufacturers have already demonstrated machines where the hard drive is replaced by flash memory. But this technology has a very significant drawback, which becomes an obstacle to replacing existing magnetic disks with this medium. Due to the design of flash memory, it allows erasing and writing of information in a limited number of cycles, which is achievable even for small and portable devices, not to mention how often this is done on computers. If you use this type of media as a solid state drive on a PC, then a critical situation will come very quickly.

This is due to the fact that such a drive is built on the property of field-effect transistors to store in a “floating” gate the absence or presence of which in the transistor is considered as a logical one or zero in binary. Writing and erasing data in NAND memory is carried out using tunneled electrons using the Fowler-Nordheim method with the participation of a dielectric. This does not require what allows you to make cells of minimal sizes. But it is this process that leads to cells, since the electric current in this case forces electrons to penetrate the gate, overcoming the dielectric barrier. However, the guaranteed shelf life of such memory is ten years. Wear of the microcircuit occurs not due to reading information, but due to operations to erase and write it, since reading does not require changing the structure of the cells, but only passes an electric current.

Naturally, memory manufacturers are actively working towards increasing the service life of solid-state drives of this type: they are striving to ensure uniformity of writing/erasing processes across the cells of the array, so that some do not wear out more than others. To distribute the load evenly, software paths are predominantly used. For example, to eliminate this phenomenon, “wear leveling” technology is used. In this case, data that is often subject to changes is moved to the address space of flash memory, so recording is carried out at different physical addresses. Each controller is equipped with its own alignment algorithm, so it is very difficult to compare the effectiveness of various models, since implementation details are not disclosed. Since the volume of flash drives is becoming larger every year, it is necessary to use more and more efficient operating algorithms to guarantee the stable functioning of the devices.

Troubleshooting

One of the very effective ways to combat this phenomenon has been to reserve a certain amount of memory, which ensures load uniformity and error correction through special logical redirection algorithms for replacing physical blocks that arise during intensive work with a flash drive. And to prevent the loss of information, cells that fail are blocked or replaced with backup ones. This software distribution of blocks makes it possible to ensure load uniformity, increasing the number of cycles by 3-5 times, but this is not enough.

And other types of similar drives are characterized by the fact that a table with a file system is entered into their service area. It prevents failures in reading information at the logical level, for example, in the event of an incorrect shutdown or a sudden interruption in the supply of electrical energy. And since the system does not provide caching when using removable devices, frequent rewriting has the most detrimental effect on the file allocation table and directory table of contents. And even special programs for memory cards are not able to help in this situation. For example, during a one-time request, the user overwrote a thousand files. And, it would seem, I only used the blocks where they were located for recording once. But service areas were rewritten with each update of any file, that is, the allocation tables went through this procedure a thousand times. For this reason, the blocks occupied by this data will fail first. Wear leveling technology also works with such blocks, but its effectiveness is very limited. And it doesn’t matter what kind of computer you use, the flash drive will fail exactly when the creator intended it to.

It is worth noting that the increase in the capacity of the microcircuits of such devices has only led to the fact that the total number of write cycles has decreased, since the cells are becoming smaller, so less and less voltage is required to dissipate the oxide partitions that isolate the “floating gate”. And here the situation is such that with the increase in the capacity of the devices used, the problem of their reliability began to worsen more and more, and the class of the memory card now depends on many factors. The reliability of such a solution is determined by its technical features, as well as the current market situation. Due to fierce competition, manufacturers are forced to reduce production costs by any means. Including due to simplified design, the use of components from a cheaper set, weakening control over production and other methods. For example, a Samsung memory card will cost more than its lesser-known analogues, but its reliability raises much fewer questions. But even here it is difficult to talk about a complete absence of problems, and it is difficult to expect anything more from devices from completely unknown manufacturers.

Development prospects

While there are obvious advantages, there are a number of disadvantages that characterize the SD memory card, which prevent further expansion of its scope. That is why there is a constant search for alternative solutions in this area. Of course, first of all, they are trying to improve existing types of flash memory, which will not lead to any fundamental changes in the existing production process. Therefore, there is no doubt about only one thing: companies engaged in the manufacture of these types of drives will try to use their full potential before switching to another type, continuing to improve traditional technology. For example, the Sony memory card is currently available in a wide range of volumes, so it is assumed that it will continue to be actively sold out.

However, today, on the threshold of industrial implementation, there is a whole range of technologies for alternative data storage, some of which can be implemented immediately upon the onset of a favorable market situation.

Ferroelectric RAM (FRAM)

The technology of the ferroelectric principle of information storage (Ferroelectric RAM, FRAM) is proposed to increase the potential of non-volatile memory. It is generally accepted that the mechanism of operation of existing technologies, which consists in rewriting data during the reading process with all modifications of the basic components, leads to a certain restraint in the speed potential of devices. And FRAM is a memory characterized by simplicity, high reliability and speed in operation. These properties are now characteristic of DRAM - non-volatile random access memory that currently exists. But here we will also add the possibility of long-term data storage, which is characterized by Among the advantages of such technology, we can highlight resistance to various types of penetrating radiation, which may be in demand in special devices that are used to work in conditions of increased radioactivity or in space exploration. The information storage mechanism here is implemented through the use of the ferroelectric effect. It implies that the material is able to maintain polarization in the absence of an external electric field. Each FRAM memory cell is formed by sandwiching an ultra-thin film of ferroelectric material in the form of crystals between a pair of flat metal electrodes, forming a capacitor. The data in this case is stored inside the crystal structure. And this prevents the effect of charge leakage, which causes the loss of information. Data in FRAM memory is retained even when the power supply is turned off.

Magnetic RAM (MRAM)

Another type of memory that is considered very promising today is MRAM. It is characterized by fairly high speed performance and energy independence. in this case, a thin magnetic film placed on a silicon substrate is used. MRAM is static memory. It does not need periodic rewriting, and information will not be lost when the power is turned off. At the moment, most experts agree that this type of memory can be called a next-generation technology, since the existing prototype demonstrates fairly high speed performance. Another advantage of this solution is the low cost of the chips. Flash memory is manufactured using a specialized CMOS process. And MRAM chips can be produced using a standard manufacturing process. Moreover, the materials can be those used in conventional magnetic media. It is much cheaper to produce large quantities of such microcircuits than all the others. An important property of MRAM memory is its instantaneous turn-on capability. And this is especially valuable for mobile devices. Indeed, in this type, the value of the cell is determined by the magnetic charge, and not by the electrical charge, as in traditional flash memory.

Ovonic Unified Memory (OUM)

Another type of memory that many companies are actively working on is a solid-state drive based on amorphous semiconductors. It is based on phase change technology, which is similar to the principle of recording on conventional discs. Here the phase state of a substance in an electric field changes from crystalline to amorphous. And this change persists even in the absence of tension. Such devices differ from traditional optical disks in that heating occurs due to the action of electric current and not a laser. Reading in this case is carried out due to the difference in the reflectivity of the substance in different states, which is perceived by the disk drive sensor. Theoretically, such a solution has a high data storage density and maximum reliability, as well as increased performance. The maximum number of rewrite cycles is high here, for which a computer is used; a flash drive in this case lags behind by several orders of magnitude.

Chalcogenide RAM (CRAM) and Phase Change Memory (PRAM)

This technology is also based on the principle that in one phase the substance used in the carrier acts as a non-conducting amorphous material, and in the second it serves as a crystalline conductor. The transition of a memory cell from one state to another is carried out due to electric fields and heating. Such chips are characterized by resistance to ionizing radiation.

Information-Multilayered Imprinted CArd (Info-MICA)

The operation of devices built on the basis of this technology is carried out according to the principle of thin-film holography. Information is recorded as follows: first, a two-dimensional image is formed and transferred to a hologram using CGH technology. Data is read by fixing the laser beam on the edge of one of the recorded layers, which serve as optical waveguides. The light propagates along an axis that is parallel to the plane of the layer, forming an output image corresponding to the information recorded earlier. The initial data can be obtained at any time thanks to the reverse coding algorithm.

This type of memory compares favorably with semiconductor memory due to the fact that it provides high recording density, low power consumption, as well as low cost of storage media, environmental safety and protection from unauthorized use. But such a memory card does not allow rewriting of information, so it can only serve as long-term storage, a replacement for paper media, or an alternative to optical disks for distributing multimedia content.

It's no secret that in the modern world, one of the most relevant goods is information. And it, like any other product, must be stored and transferred. Portable storage devices were created for this purpose. In the recent past, this role was played by floppy disks and CDs, capable of storing a very small amount of information despite being large in size. With the development of computer technology, storage media gradually decreased in size, but the volume of data stored in them increased many times over. This led to the emergence of a new portable storage device - the USB flash drive.

Flash memory- a special type of non-volatile, rewritable semiconductor memory.

Let's take a closer look: non-volatile - does not require additional energy to store data (energy is required only for recording), rewritable - allowing the data stored in it to be changed (rewritten) and semiconductor (solid-state), that is, not containing mechanically moving parts (like regular hard drives or CDs) ), built on the basis of integrated circuits (IC-Chip).

Literally before our eyes, flash memory has transformed from an exotic and expensive means of data storage into one of the most popular storage media. Solid-state memory of this type is widely used in portable players and pocket computers, in cameras and miniature flash drives. The first production samples worked at low speed, but today the speed of reading and writing data to flash memory allows you to watch a full-length movie stored in a miniature chip or run a “heavy” Windows XP-class operating system.

Due to its low power consumption, compact size, durability and relatively high performance, flash memory is ideal for use as storage in portable devices such as digital photo and video cameras, cell phones, laptop computers, MP3 players, digital voice recorders, and etc.

Story

Initially, solid-state hard drives were developed for high-speed servers and were used for military purposes, but as is usually the case, over time they began to be used for civilian computers and servers.

Two classes of devices emerged: in one case, they sacrificed erase circuits to obtain high-density memory, and in the other case, they made a fully functional device with a much smaller capacity.

Accordingly, the efforts of engineers were aimed at solving the problem of the density of the erase circuits. They were crowned with success by the invention of Toshiba engineer Fujio Masuoka in 1984. 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. 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.

It is sometimes argued that the name Flash in relation to the type of memory is translated as “flash”. Actually this is not true. One version of its appearance says that for the first time in 1989-90, Toshiba used the word Flash in the context of “fast, instant” when describing its new chips. In general, Intel is considered the inventor, introducing flash memory with NOR architecture in 1988.

The advantages of USB flash cards over other drives are obvious:

small dimensions,

very light weight,

quiet operation,

possibility of rewriting,

good resistance to mechanical stress, unlike CDs and floppy disks (5-10 times higher than the maximum permissible for conventional hard drives),

withstands severe temperature changes,

no moving parts, which reduces energy consumption to a minimum,

no connection problems - USB outputs are available on almost any computer,

large amount of memory,

recording information into memory cells,

Information storage period is up to 100 years.

Flash memory consumes significantly (about 10-20 times or more) less energy during operation.

It should also be noted that to work with a USB flash drive, you do not need any third-party programs, adapters, etc. The device is recognized automatically.

If you write to a flash drive 10 times a day, it will last for about 30 years.

Operating principle

The operating principle of semiconductor flash memory technology is based on changing and recording the electrical charge in an isolated area (pocket) of the semiconductor structure.

The change in charge (“write” and “erase”) is accomplished by applying a high potential between the gate and source so that the electric field strength in the thin dielectric between the transistor channel and the pocket is sufficient to cause a tunneling effect. To enhance the effect of electron tunneling into the pocket during writing, a slight acceleration of the electrons is applied by passing a current through the field-effect transistor channel.

Schematic representation of a floating gate transistor.

Between the control gate and the channel through which current flows from source to drain, we place the same floating gate, surrounded by a thin layer of dielectric. As a result, when current flows through such a “modified” field-effect transistor, some high-energy electrons tunnel through the dielectric and end up inside the floating gate. It is clear that while the electrons were tunneling and wandering inside this gate, they lost some of their energy and practically cannot return back. SLC and MLC devices

There are devices in which the elementary cell stores one bit of information and several. In single-bit cells, there are only two charge levels on the floating gate. Such cells are called single-level cells. single-level cell SLC). In multi-bit cells, more charge levels are distinguished; they are called multi-level. multi-level cell, MLC). MLC devices are cheaper and more capacious than SLC devices, but the access time and number of rewrites are worse.

Audio memory

A natural development of the idea of ​​MLC cells was the idea of ​​recording an analog signal into the cell. Such analog flash chips are most widely used in sound reproduction. Such microcircuits are widely used in all kinds of toys, sound cards, etc.

Nor flash memory

Design NOR uses a classic two-dimensional matrix of conductors (“rows” and “columns”) in which one cell is installed at the intersection. In this case, the conductor of the rows was connected to the drain of the transistor, and the conductor of the columns to the second gate. The source was connected to a common substrate for all. With this design, it was easy to read the state of a particular transistor by applying a positive voltage to one column and one row.

This type of flash memory is based on the NOR algorithm, since in a floating-gate transistor too low a gate voltage means one. This type of transistor consists of two gates: floating and control. The first gate is completely insulated and has the ability to retain 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 the so-called tunneling effect occurs. Most of the electrons are transferred (tunneled) through the insulator layer and enter the floating gate. The charge on the floating gate of the transistor changes the drain-source "width" and conductivity of the channel, which is used for reading. Writing and reading cells are very different in power consumption: for example, flash drives consume more current when writing than when reading (consuming very little power). 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 are transferred 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 using the new NAND architecture.

What is Flash Memory?

Flash Memory/USB drive or flash memory is a miniature storage device used as an additional storage medium for information. The device connects to a computer or other reading device via a USB interface.

A USB flash drive is designed to be read repeatedly over a specified lifespan, which typically ranges from 10 to 100 years. You can write to flash memory a limited number of times (about a million cycles).

Flash memory is considered more reliable and compact compared to hard disk drives (HDD) because it has no moving mechanical parts. This device is quite widely used in the production of digital portable devices: photo and video cameras, voice recorders and MP3 players, PDAs and mobile phones. Along with this, Flash Memory is used to store firmware in various equipment, such as modems, PBXs, scanners, printers or routers. Perhaps the only drawback of modern USB drives is their relatively small volume.

History of Flash Memory

The first flash memory appeared in 1984, it was invented by Toshiba engineer Fujio Masuoka, whose colleague Shoji Ariizumi compared the principle of operation of this device with a photo flash and first called it “flash”. The public presentation of Flash Memory took place in 1984 at the International Electronic Devices Seminar held in San Francisco, California, where Intel became interested in this invention. Four years later, its specialists released the first commercial flash processor. The largest manufacturers of flash drives at the end of 2010 were Samsung, occupying 32% of this market, and Toshiba - 17%.

How does a USB drive work?

All information written to a Flash drive and stored in its array, which consists of floating gate transistors called cells. In conventional single-level cell devices, each cell “remembers” only one bit of data. However, some new chips with multi-level cells (multi-level cell or triple-level cell) are capable of storing a larger amount of information. In this case, a different electrical charge must be used on the floating gate of the transistor.

Key Features of a USB Drive

The capacity of currently available flash drives ranges from several kilobytes to hundreds of gigabytes.

In 2005, specialists from Toshiba and SanDisk presented a NAND processor, the total volume of which was 1 GB. When creating this device, they used multi-level cell technology, where a transistor is capable of storing several bits of data using a different electrical charge on a floating gate.

In September of the following year, Samsung presented to the public a 4-gigabyte chip developed on the basis of a 40-nm technological process, and at the end of 2009, Toshiba technologists announced the creation of a 64 GB flash drive, which was launched into mass production at the beginning of next year. of the year.

In the summer of 2010, the presentation of the first 128 GB USB drive in the history of mankind, consisting of sixteen 8 GB modules, took place.

In April 2011, Intel and Micron announced the creation of an 8 GB MLC NAND flash chip with an area of ​​118 mm, almost half the size of similar devices, the mass production of which started at the end of 2011.

Types of memory cards and flash drives

It is used mainly in professional video and photo equipment, since it has rather large dimensions (43x36x3.3 mm), as a result of which it is quite problematic to install a Compact Flash slot in mobile phones or MP3 players. At the same time, the card is considered not very reliable, and also does not have a high data processing speed. The maximum allowable capacity of Compact Flash currently reaches 128 GB, and the data copying speed has increased to 120 MB/s.

RS-MMC/Reduced Size Multimedia Card- a memory card that is half the length of a standard MMC card - 24x18x1.4 mm and weighs about 6 grams. At the same time, all other characteristics and parameters of a regular MMC card are preserved. To use RS-MMC cards, you must use an adapter.

MMCmicro- a miniature memory card with dimensions of only 14x12x1.1 mm and designed for mobile devices. To use it, you must use a standard MMC slot and a special adapter.

Despite the parameters and dimensions of 32x24x2.1 mm being very similar to the MMC card, this card cannot be used with a standard MMC slot.

SDHC/SD High Capacity is a high-capacity SD memory card, known to modern users as SD 1.0, SD 1.1 and SD 2.0 (SDHC). These devices differ in the maximum amount of data that can be stored on them. Thus, there are capacity restrictions in the form of 4 GB for SD and 32 GB for SDHC. However, the SDHC card is backward compatible with SD. Both options come in three physical size formats: standard, mini and micro.

microSD/Micro Secure Digital Card- this is the most compact removable flash memory device as of 2011, its dimensions are 11x15x1 mm, which allows it to be used on mobile phones, communicators, etc. The write protection switch is located on the microSD-SD adapter, and the maximum possible card capacity is 32 GB.

Memory Stick Micro/M2- a memory card whose format competes in size with microSD, but the advantage remains with Sony devices.

It has become indispensable in mobile devices (PDAs, tablets, smartphones, players). USB flash drives and memory cards for electronic devices (SD, MMC, miniSD, etc.) have been developed based on flash memory.

Definition 1

Flash memory(Flash Memory) – solid-state semiconductor non-volatile and rewritable memory.

Information can be read from flash memory a large number of times within the life of the drive (from $10$ years), but the number of write processes is limited (about $100\000$ rewrite cycles).

Flash memory is considered a more reliable type of storage medium, because... does not contain moving mechanical parts (such as a hard drive).

Advantages of flash memory:

• high speed data access;
• low power consumption;
• vibration resistance;
• ease of connection to a PC;
• compact dimensions;
• cheapness.

Disadvantages of flash memory:

• limited number of write cycles;
• sensitivity to electrostatic discharge.

History of Flash Memory

Flash memory was first invented in $1984.

The name “flash” comes from the English “flash”, because the process of erasing data resembled a photographic flash.

In $1988, the first commercial NOR flash processor was released. The following year, NAND flash memory architecture was developed, which featured faster write speeds and a smaller circuit area.

Principle of operation

The elementary data storage cell is a floating gate transistor that can hold electrons (charge) is the elementary data storage cell in flash memory. Based on the transistor, the main types of NAND and NOR flash memory have been developed. The operating principle is based on changing and recording the electric charge in an isolated region (“pocket”) of the semiconductor structure.

Figure 1. NOR memory architecture

Figure 2. NAND memory architecture

Flash memory manufacturers use 2 types of memory cells:

• MLC(Multi-Level Cell - multi-level memory cells) - more capacious cells and cheaper, but characterized by long access times and a small number of write/erase cycles (about $10\000$);
• SLC(Single-Level Cell - single-level memory cells) - cells with shorter access times and a maximum number of write/erase cycles ($100\000$).

Figure 3. Main elements of a USB flash drive: $1$ – USB connector, $2$ – controller, $3$ – PCB board, $4$ – NAND memory module, $5$ – crystal oscillator, $6$ – LED indicator , $7$ – write protection switch, $8$ – space for an additional memory chip.

Application

Exists There are two main uses for flash memory:

• as a mobile information carrier;
• as a software repository for digital devices.

Often both methods are combined in one device.

The use of NOR memory, which has a relatively small volume, is to provide fast access to random addresses and guarantee the absence of faulty elements (standard ROM chips for working with a microprocessor, computer boot chips (POST and BIOS), medium-sized data storage chips, for example ,DataFlash). Typical volumes range from $100$ KB to $256$ MB. NAND memory is used in mobile devices and storage media that require large amounts of storage. Basically, these are USB keys and memory cards of all types, as well as mobile devices (phones, cameras, players). NAND memory is built into household appliances: cell phones and TVs, network routers, access points, game consoles, photo frames and navigators.

Figure 4. Different types of flash cards

Types and types of memory cards and flash drives

Note 1

CF(Compact Flash) is the oldest memory type standard. It has high reliability, a fairly large volume ($128 GB or more) and high data transfer speed ($120 MB/s). Due to its large size, it is used in professional video and photographic equipment.

MMC (Multimedia Card) is small in size, highly compatible with various devices and contains a memory controller. SD Card (Secure Digital Card) is the result of the development of the MMC standard. The card has cryptographic protection against unauthorized copying, increased protection of information from accidental erasure or destruction, and a mechanical write-protection switch. Maximum capacity up to $4$ GB. SDHC (SD High Capacity) has a maximum capacity of $32$ GB.

There are also miniSD and microSD cards.

Note 2

The main manufacturers of NAND flash memory are Micron/Intel, SK Hynix, Toshiba/SanDisk, Samsung. The main manufacturers of NAND flash memory controllers are Marvell, LSI-SandForce and NAND memory manufacturers.

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

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

Flash memory is a type of solid-state, non-volatile, rewritable memory. Unlike a hard drive, a flash drive has a high read speed, which can reach up to 100 MB/s, and is very small in 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 turned off, autonomously.

Today, flash drives with capacities ranging from 256 megabytes to 16 gigabytes are available on the market. But there are media with a larger volume.

Additional flash memory functions 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.

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 this type of memory to be used very widely. These include 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 fairly 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 CompactFlash (CF), there are two types CF type I and CF type II. Has good speed, capacity and price.
The disadvantages include the size 42*36*4 mm. It is quite versatile and is used in many devices.

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

SmartMedia- thin and cheap, but not high protection against abrasion.

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

Secure Digital (SD) with comparable dimensions to the Multimedia Card, it has greater capacity and speed. But more expensive.

MemoryStick- 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 cards listed, there are other types of flash cards

You should choose a flash card based on your needs, taking into account that the larger the capacity and speed, the more expensive the flash card.