How to recover deleted files from flash drive? What is the difference between flash drives and external hard drives? How to recover data?

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What should I do if I accidentally deleted files from a flash drive? Stop! Whatever you do next, in no case do not write anything to this USB flash drive. After that, you should evaluate how important your data is so that you can try to recover the data yourself. If you decide that the data is very valuable to risk it, then it is better to take the flash drive to a professional data recovery company. Do you have any questions? Leave your phone and the manager will call you back

A slang word very often used in circulation - flash drive, so firmly entrenched in everyday life that many have forgotten how to properly call this device, while others do not know at all.

This miniature device is used to copy, store and transmit digitized information. Correct device name:

USB indicates a way to connect a flash drive to other devices through special ports, and flush reports that the functions of storing and copying information are implemented using non-volatile flash memory on semiconductors.

The advantages of flash drives are in their small size, quiet operation and shock resistance.

Electronics sellers in stores use the name flash drive.

Officially flash drive It is called USB flash drivequot ;, as it is a storage device that uses flash memory as a medium and connects to a computer or reader via USB.

• USB flash drive

  So Wikipedia officially calls the flash drive.

  By the way, I would have the word and " USB flash drive" recommended writing precisely through the letter equot ;. The same Wikipedia gives the following official English name for this device: USB flash drive". In this case, we are interested in the word flash. It is from him that the word flash drivequot ;. The English language also has the word flashquot ;, which has nothing to do with a flash drive.

The word flash drive - this is the abbreviated name flash cardsquot ;. You can also find the names memory card and USB flash drive is a storage medium converted to flash memory (you can read more about flash memory here), so the main characteristic of a flash card is the amount of memory.

The word flash drive is very widely used in everyday life, most people do not even know the correct name of this device. In full name:

The word flash means that information is stored using Flash memory, a USB connection to a computer.

A flash drive is officially considered to be a USB flash drivequot ;, which is able to save the information copied to it and provides the ability to repeatedly transfer data from it to other electronic devices.

A flash drive is properly called a USB flash drive. USB is called because it plugs into this port on the computer. It is called a drive because it can store information and conveniently carry a large volume with you. It is necessary to handle it carefully and stop working with it before pulling it out of the connector.

What is the correct name flash drive, which has become so familiar to everyone - in fact, few people think about it. Other names that are used quite often are memory stick or USB memory stick, flash (or flash) card, or flash/flash drive.

In this case, the correct name of the flash drive is:

a device with removable media or flash memory or just a memory card

Well, for us it is accepted this is " call a flash drive, it is a flash drive, they just call it correctly " USB flash drive ", and USB stands for " Universal serial bus", also called briefly " flash, flash drive, flash drive

The flash drive is called flash card or flash memory card. Although in online stores this device is called USB stick, so this is probably more correct.

There is also just a memory card, but this is somewhat different, those memory cards are used for mobile phones, although the principle of storing information seems to be the same for them: a flash method of remembering. Now they also began to make BIOS on nm.

information

A storage medium using flash memory (eng. Flash - “fast, instantaneous”) is a microcircuit with electronic non-volatile memory capable of storing recorded information for an unlimited time and maintaining its state until an electrical signal of a different polarity is applied to the outputs. These are high-quality universal rewritable storage media targeted at consumer electronics products and next-generation computer equipment.

Flash memory is available in the following types: CompactFlash, SmartMedia, Memory Stick, Floppy Disks, MultiMedia Cards, etc.

MultiMedia cards, for example, weigh less than two grams, are the size of a postage stamp, and have memory capacities ranging from 8 to 64 MB. Such cards can replace not only floppy disks, but magneto-optical, small hard disks and rewritable CDs. Modern flash cards have a capacity that is a multiple of two to the power: 26 = 64, 27 = 128, 256 = 28 MB, and so on. It is assumed that the maximum capacity of such cards will reach units of GB. Such plug-in cards are used in digital voice recorders, portable players, camcorders, car radios, personal digital assistants (PDAs), cell phones and multimedia projectors.

Information carriers distinguish by physical structure(magnetic, semiconductor, dielectric, etc.), material type(paper, plastic, metal, combined), data presentation form(printed, handwritten, magnetic, perforated), reading principle(mechanical, optical, magnetic, electrical), design(tape, disk, card).Information carriers can also be classified according to the type of messages stored on them, and the materials of information carriers are characterized by the purpose of their use.

By intended use data carrier materials can be classified as materials used for recording, presenting and storing textual, digital, graphic data, static and dynamic images, sound (magnetic and non-magnetic) or a combination thereof, for example, multimedia data. Both classifications are closely interconnected; moreover, it is impossible to unambiguously classify carrier materials. The kinds of different messages are shown in Table 5-1.

Table 5-1

Types of different messages

Message type	Information carrier
Text	Document
Sound	Phonogram
Image (static)	Photograph, graphics, drawing, etc., transparencies (slide), hologram, static image or text information scanned with a PC
Image (dynamic)	Animation, video film, motion picture, TV
Combination of different types of information	Multimedia

as static carriers images used: paintings, etchings, drawings, etc. on canvas, cardboard, paper, film, etc.; video cassettes with magnetic tapes for VCRs and video players; magnetic vinyl diskettes; removable and non-removable hard and magneto-optical disks; compact plastic or glass laser discs ( CD, DVD ) used in computers; slides and transparencies, photographic materials, holographic plates, plates with memory for digital cameras such as flash memory, etc.

For the operation of audio-video equipment as sound carriers and/or dynamic images used: films and plastic gramophone records, magnetic audio and audiovisual tapes, films, vinyl diskettes, hard magnetic, magneto-optical disk drives, compact disks, memory plates for digital cameras and cameras, holographic plates, etc.).

multimedia data carriers magnetic audio and audiovisual tapes, floppy disks, drives on hard magnetic, magneto-optical disks, CDs, memory plates are considered.

Different requirements are imposed on information carriers for their operation and storage (climatic, sanitary and hygienic, fire-prevention, technical, technological, etc.).

Consider the basic materials of information carriers and their forms.

carriers images:

1. Paper . Historians claim that paper was invented in China about 2,000 years ago. However, much earlier (approximately since VIII century AD), the ancient Egyptians made scrolls from papyri, from where the word denoting the paper carrier "papyr" came from. Then the basis of paper carriers were rice straw, bamboo, rags, wood and other materials.

Synthetic (polyethylene) paper has been industrially used abroad since April 1967. The fibers of the material, called " Tyvek» ( Tyvek ) have a thickness (diameter) of 0.5–1 µm. It is a smooth and opaque material that incorporates the best properties of film, paper and fabric. It has a low specific gravity, high strength, resistance to punctures, tear and abrasion, vapor permeability, water repellency, rot resistance and biological inertness. Experts say that this material can replace traditional paper, especially in the manufacture of envelopes and any printing.

The material is resistant to most chemicals and is suitable for varnishing, laminating, heat sealing and bonding. It retains strength and flexibility up to a temperature of 73°C. It is believed that it is most suitable for outdoor advertising, covers of textbooks, geographical maps, guidebooks, etc., as it does not fray on the folds and does not deteriorate from water. However, to print on such material, you have to use special inks.

Similar material " Polylith» ( Polylith ) was imported to Russia in 1998. It is made from polypropylene resin mineral hardened with a mixture of neutral calcium and titanium dioxide to give a white and dull finish. It is the cheapest of synthetic materials, is resistant to water, heat, oil and chemicals. Another similar material is Robuskin» ( Robuskin ), an important distinguishing feature of which is the ability to print on it with conventional inks with virtually no readjustment of the printing equipment used for plain paper. There are, of course, other synthetic materials, including those with a self-adhesive backing.

The paper base is used in books, manuscripts, maps, diagrams and other similar documents. From the beginning of the appearance of manuscripts, books and until the middle XIX centuries, they were created mainly on paper from cotton and linen fibers. This is durable paper. From the end of the 19th and into the 20th centuries, paper was used mainly sulfite pulp and wood pulp. Modern books are mainly used as a carrier cellulosic materials.

2.Canvas, cardboard, hardboard and other art materials , on which pictures are written, engravings and etchings are printed, usually are specially processed materials of woodworking (cardboard, hardboard) and weaving (canvas) industries. In addition, waste is used as a material for these purposes. wood(first) and linen or the like. (second). In this case, the canvas is coated with a special composition (primed) before applying paints to it.

3. photographic materials (negative, positive) are used for media such as photographic plate, photographic film, film or filmstrip, transparencies or slide, microfilm or microfiche. For these media, films are mainly used on cellulose, polyester base.

4. gramophone record usually made by pressing plastic mass(vinyl). Represents a round disk, on the surface of which concentric (spiral) grooves are applied, going from the outer side of the disk to its center. Discs differ in diameter, recording speed, number of audio channels and content.

To sizeThese disks are divided into three types:

1. "Giant" - 30 cm in diameter (playing time of one side 25-30 minutes).

2. "Grand" - with a diameter of 25 cm (the playing time of one side is 12-15 minutes).

3. "Mignon" - 17.5 cm in diameter (playing time of one side is 6-8 minutes).

By disk rotation speed gramophone records come in 4 types: 16, 33, 45, 78 rpm.

By record type records are divided into: monophonic, stereophonic and long-playing. Long-playing records have narrower grooves and a smaller distance between them (pitch) than conventional records, which allows for longer playing times. Stereo records contain a two-channel recording (left and right channel along the left and right walls of the groove).

5. Hologram - a plate with lithium niobate crystals or a photopolymer film. Holographic memory, unlike CD technology, represents the entire volume of the storage medium of the carrier, while data elements are accumulated and read in parallel. It allows you to place 1 TB (trillion bytes) in a crystal the size of a sugar cube, that is, information with a volume of more than 1000 CDs. Modern holographic storage devices are called HDSS (holographic data storage system).

6. Magnetic tapes in audio and video cassettes, streamers, magnetic disks in PC floppy disks are made of synthetic materials with a magnetic layer (usually iron oxide) on the lavsan or vinyl basis. Disks in HDD are made of light metal (aluminum) or glass and coated on both sides with a magnetic layer.

7. Magneto-optical disks (MO disks) are placed in a plastic case. Recording by a laser with a temperature of about 200°C on the magnetic layer occurs simultaneously with a change in the magnetic field. This property provides high reliability of storage of recorded information.

8. AT optical (laser) disks - CDs for audio-video recordings and other machine-readable information. The carrier material in a CD is polycarbonate, polyvinyl chloride or special glass with a reflective (sprayed) aluminum layer. Use optical recording method. They can be classified as a medium, a carrier of various text, digital, sound and video recordings, multimedia, etc.

Distinguish: AudioCD CD-ROM, CD-R, CD-R W and others.

CD- ROM. The CD-ROM replication technology is similar to the production of gramophone records - printing (stamping) from matrices. In the process of writing, the laser acts on the photoresist, leaving lines-marks on it. The photoresistive layer is developed and metallized. Then, using the electroforming method, a second one is made from the original - completely metal, and intermediate copies are created from it by stamping. Many matrices are created from them, from which the manufactured products are replicated on CDs.

CD-Rused for a single laser recording or a single recording with the addition of several recordings to the same disc in the form of sessions (recording).

CD-RWallow you to repeatedly (hundreds and a thousand times) erase and write information to them.

Compact discs are distinguished by high recording density (about 300 thousand pages of text in A4 format), the ability to quickly search for information stored on them (a few milliseconds), and the durability of the media (tens of years).

This carrier has up to four recording layers and a capacity from units (4.7) to tens (17) GB. In this case, the duration of the recording increases to 8 hours. Increasing the information capacity of the disk is achieved through the use of a laser with a shorter wavelength of radiation (0.635-0.66 instead of 0.78 microns), as well as video data compression technology in standards MPEG , which made it possible to increase the density of data recording on these disks and the speed of reading information from them. For example, the digital video data rate is 1.3 Mbps, which provides high quality video (better than VHS ), and on the monitor is better than on the television receiver.

There are many varieties of compact discs that differ in the use of various media materials, recording methods, etc. Among the new devices, it should be noted “blu- rayDisc».

Blu-ray Disc Technology developed at the end of 2001. Since February 2002, its specification has been supported by a number of well-known foreign companies. Disks with a diameter of 12 mm have a capacity of 23.3; 25 and 27 GB, the thickness of the transparent protective layer is 0.1 mm, and the track width is 0.32 mm, which allowed not only to provide more capacity, but also to increase the read / write speed. The base speed of devices for working with these drives (1x) is 36 Mbps (5.5 MB/s). Recall that at DVD this parameter is 1.3 Mb / s, and for CD – 150 KB/s respectively. According to the developers, these discs are well suited for recording television and video programs broadcast in digital format.

9. Flash -memory - solid-state built-in and replaceable thin memory wafer made of semiconductor materials. Contains a flash memory chip with exposed contacts. These cards draw power from the devices they connect to. The amount of stored information is from 16 MB to 4 GB.

Information is recorded and stored on different media by different methods. Forms of storage and storage media are presented in table. 5-2.

Table 5-2

Forms of storage and storage media

Information form	Information carrier	Information recording method
Mechanical	plate	analog
Optical	paper	sign-symbolic
	film film	analog
	laser audio disc CD-A	analog
	laser disc CD - ROM , DVD	digital
Magnetic	audiovisual film	analog
	floppy disks	digital
	hard disks	digital

The possibilities of using various media and their materials for recording and using even one type of data are very diverse. So, text can be recorded on almost any media, presented as a static or dynamic image on the following media materials (Fig. 5-2).

Rice. 5-2. Materials of text information carriers

Sound, recorded on various media, is an important component of various funds and collections. Such media may be provided to users and used for official purposes; be stored for a short time or for a long time, etc.

Audio recordings and gramophone records, available in one copy, are not recommended to be issued to users at home. It is better for information services that serve users to purchase sound recordings in at least two copies in order to keep one of them in the reserve fund. If they contain records in one single copy, then it is advisable to rewrite them, for example, on a magnetic tape, floppy disk or disk to replenish the main fund of sound recordings provided to users, and store the first copy in the reserve fund.

The sound is recorded and stored on the storage media shown in Fig. 5-3.

Rice. 5-3. Audio media

If there are high-quality tape recorders or music centers in the information services serving users, the purchased one copy of the sound recording on magnetic tape is stored in the reserve fund, and copies are made from it on their own, which are issued to users.

Static video information obtained in the process of photographing and processing photographic materials (development and printing). Until the mid-1930s, many photographic materials were produced on a cellulose-nitrate basis (nitrate-based film was produced until 1951). In the late 1940s, silver-free powder photography appeared - xerography. In the 1950s, a way to create short-lived copies appeared - thermography.

The type of photography is micrography. Photographic recording allows documents to be stored in the form of microfilm and microfiche, i.e. microforms - microcarriers. Microcarriers are photographically reduced copies by tens and hundreds of times from various originals (manuscripts, drawings, drawings, printed texts, etc.).

Microforms serve as a protective copy of the original. The basis of micrographic film is plastic bases. It is the most important factor determining the durability and safety of the film. The insurance (archival) funds store reference negatives of the first generation (master negatives), which are used in the microfilming of manuscripts, archival materials and rare publications.

Vesicular, photothermoplastic and electrophotographic films are also used in micrography. They are mainly used for working microforms. Microcarriers are used in information centers, archives, libraries, research, design and other institutions.

Relatively cheap and widespread type of audio-video data carrier are magnetic tapes and disks. They are convenient to use. Reliable methods have been developed for the physical protection of magnetic media from damage, errors during reading, and spontaneous disappearance of data. Thus, it is recommended to carefully wind, clean and rewind magnetic tapes in both directions every six months, and copy every 12 months. The UK Government Computer Agency believes that magnetic tapes can be stored for up to three years under normal conditions, but recommends checking samples every 18 months.

A modern way of recording audiovisual data presented to users is to "digitize" them, followed by recording them on CDs. Work on creating a method for digital recording and playback of sound has been intensively carried out since the early 70s of the twentieth century. At the end of 1982, the first CDs appeared on sale.

The life of CDs will be significantly reduced by excessive heat, humidity, or direct sunlight. Therefore, it is recommended to store discs in a cool, dark and dry place.

Flash memory is a type of durable memory for computers that can be reprogrammed or electrically erased. Compared to Electrically Erasable Programmable Read Only Memory, actions can be performed on it in blocks that are in different places. Flash memory costs much less than EEPROM, which is why it has become the dominant technology. Especially 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 on a 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 notoriety in the gamer world, where it is often used in a blunder to store game progress data.

general description

Flash memory is a type that can store information on its board for a long time without using power. In addition, we can note the highest data access speed, as well as the best 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 accumulators. Another indisputable 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 method of accessing data in flash memory is very different from that used for conventional views. Low-level access is provided through the driver. Ordinary 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.

Device and principle of operation

At the moment, flash memory is widespread, which is created on single-transistor elements with a "floating" gate. This allows for greater storage density than DRAM, which requires a pair of transistors and a capacitor element. At the moment, the market is replete with various technologies for building basic elements for this type of media, which are developed by leading manufacturers. What distinguishes them is the number of layers, methods of recording and erasing information, as well as the organization of the structure, which is usually indicated in the title.

At the moment, there are a couple of types of microcircuits 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 rather large cell sizes, and there is a possibility for fast random access, which allows programs to be executed directly from memory. The second one is characterized by smaller cell sizes, as well as fast sequential access, which is much more convenient if it is necessary to build block-type devices where large information will be stored.

In most portable devices, the SSD uses the NOR type of memory. However, now USB devices are becoming more and more popular. They use NAND memory. Gradually, it displaces the first.

The main problem is the 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 carrier. Due to the characteristics of the flash memory device, it allows erasing and writing information for 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 the binary. Recording and erasing data in NAND memory are performed using tunneled electrons using the Fowler-Nordheim method. with the help of a dielectric. This is not required, which allows you to make cells of minimal size. But it is this process that leads to the cells, since the electric current in this case causes the electrons to penetrate the gate, overcoming the dielectric barrier. However, the guaranteed shelf life of such memory is ten years. The 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 this type of solid-state drives: they are striving to ensure uniform write / erase processes across array cells so that some do not wear out more than others. Software paths are predominantly used to evenly distribute the load. For example, to eliminate this phenomenon, the technology of "wear leveling" is used. In this case, data that is often subject to changes is moved to the address space of the flash memory, so the 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 certain models, since implementation details are not disclosed. Since the volume of flash drives is growing every year, it is necessary to apply more and more efficient algorithms to ensure the stability of the devices.

Troubleshooting

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

And other types of such drives are characterized by the fact that a table with the 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 for caching when using removable devices, frequent overwriting has the most detrimental effect on the file allocation table and directory contents. And even special programs for memory cards are not able to help in this situation. For example, with a single access, the user rewrote a thousand files. And, it would seem, only once used for recording the blocks where they are located. But the service areas were overwritten 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 particular data will fail first of all. Wear leveling technology works with such blocks, but its effectiveness is very limited. And it doesn’t matter what computer you use, the flash drive will fail exactly when it is provided by the creator.

It is worth noting that the increase in the capacity of the microcircuits of such devices only led to the fact that the total number of write cycles was reduced, as the cells become smaller, therefore, less and less voltage is required to dissipate the oxide partitions that isolate the “floating gate”. And here the situation is such that with an increase in the capacity of the devices used, the problem of their reliability has become more and more aggravated, 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 the cost of production in any way. Including due to the simplification of the design, the use of components from a cheaper set, the weakening of control over manufacturing, and in other ways. For example, a Samsung memory card will cost more than lesser-known analogues, but its reliability raises much fewer questions. But even here it is difficult to talk about the complete absence of problems, and it is difficult to expect anything more from devices from completely unknown manufacturers.

Development prospects

Despite the obvious advantages, there are a number of disadvantages that characterize the SD-memory card, preventing 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 try to improve the 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: the companies involved 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 sizes, so it is expected that it will continue to be actively sold.

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

Ferroelectric RAM (FRAM)

Ferroelectric RAM (FRAM) technology 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 in the process of reading 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 of operation. These properties are now characteristic of DRAM - the non-volatile random access memory that exists at the moment. But this will also add the possibility of long-term data storage, which is characterized. Among the advantages of such a technology, resistance to various types of penetrating radiation can be distinguished, 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 is implemented here 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 placing an ultra-thin film of ferroelectric material in the form of crystals between a pair of flat metal electrodes that form 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. The data in the FRAM memory is retained even when the power supply is switched off.

Magnetic RAM (MRAM)

Another type of memory that is considered very promising today is MRAM. It is characterized by rather high speed performance and energy independence. in this case, a thin magnetic film placed on a silicon substrate is used. MRAM is a static memory. It does not need to be periodically overwritten, and the 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 the 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 according to a specialized CMOS process. And MRAM chips can be produced using a standard manufacturing process. And the materials can be those that are used in conventional magnetic media. It is much cheaper to produce large batches of such microcircuits than all the others. An important property of MRAM memory is the ability to turn on instantly. 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 electric charge, as in traditional flash memory.

Ovonic Unified Memory (OUM)

Another type of memory that many companies are actively working on is the solid-state drive based on amorphous semiconductors. It is based on the phase transition technology, which is similar to the principle of recording on conventional discs. Here the phase state of matter 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 discs in that the heating occurs due to the action of an 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 drive sensor. Theoretically, such a solution has a high storage density and maximum reliability, as well as increased speed. The indicator of the maximum number of rewriting cycles is high here, for which a computer is used, the 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 basis when in one phase the substance used in the carrier acts as a non-conductive amorphous material, and in the second it serves as a crystalline conductor. The transition of the storage 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, which is transferred to a hologram using CGH technology. Data is read by fixing the laser beam on the edge of one of the layers being recorded, which serve as optical waveguides. 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 media cost, environmental safety and protection from unauthorized use. But such a memory card does not allow information to be rewritten, therefore it can only serve as a long-term storage, a replacement for paper media, or an alternative to optical discs for distributing multimedia content.

Hi To all readers of the blog site, today I would like to tell you what a flash drive is, which has probably already penetrated into every home where there is a computer. A flash drive (also known as a flash drive, USB key fob, USB Drive, flash drive, flash card) is a relatively small device for reliable storage and transfer of any digital information, created on the basis of Flash chip (NAND) technology. Flash memory was invented by the Japanese Fuji Masuoka in 1984 (during his time at Toshiba). The name "flash" was coined by Fuji's colleague, developer Shoji Ariizumi. The name of the device comes from the English word Flash - flash, flash. The undoubted leaders in the mass production of flash memory are Toshiba (about 20% of the market) and Samsung (more than 30% of the market).

Advantages of devices with flash memory:

• Relatively light weight, portability, quiet operation.
• Versatility (modern computers, DVD players, TVs have USB connectors).
• They are much more resistant to various mechanical influences (shocks, vibrations) compared to hard drives, since they are much lighter.
• Maintain their performance in a very wide range of temperatures.
• They have low power consumption.
• Protected from dust and scratches, which have always been a big problem for optical media, as well as floppy disks.

Disadvantages of Flash Memory Devices:

• Before failure, the number of write-erase cycles is rather limited. The devices are able to securely store digital data completely autonomously for up to 5 years on average. The most advanced samples - up to 8-10 years.
• Read and write speeds are limited by USB bandwidth. There are also a number of other disadvantages of the USB connector.
• Unlike CDs, these devices are sensitive to electrostatic discharge (especially in winter) as well as to radiation.

Basically, flash drives are divided into USB Flash Drive (USB key fobs) and Flash Card (flash cards). A flash card or memory card is a fairly compact electronic storage device used to store digital information. Almost all modern memory cards are based on flash memory, although, in principle, other technologies can be used.

Today, memory cards are very widely used in all kinds of electronic devices, including mobile phones, digital cameras, laptops, desktop computers (through a card reader), game consoles, MP3 players, etc. Memory cards are rewritable, compact, non-volatile (can reliably store digital data without power consumption).

There are cards with unprotected, so-called "full-accessible memory", for which there are no restrictions on writing and reading data, as well as cards with protected memory, which use a special permission mechanism for writing, reading and deleting information. Secure memory cards usually contain an immutable identification data area.

Flash memory, made on microcircuits, has a rather compact (miniature) appearance. For this reason, it is often used in handheld computers. It is slower than random access memory chips, and therefore it is not used as the main memory of a computer.

Flash memory cards built into special cases with USB connectors are widely used by almost all computer owners. The reason for this lies in the fact that these devices are compact and have a decent capacity. USB flash drives come in a variety of sizes and shapes. They are made in the form of key chains, fountain pens, children's toys and much more.

A wide variety of USB key fobs are widely used to connect to popular USB ports of a computer, DVD player, car radio, digital camera, etc. Using a removable disk (USB Flash Disk) you can easily and quickly transfer data from one computer to another. The transfer speed in these devices is usually higher, and the case is much stronger than that of flash cards.

USB flash drives (flash drives, flash drives, flash drives) are popular and reliable storage devices that use flash memory as a carrier and are connected to a computer or other device that reads information via a USB interface.

USB flash drives are removable and rewritable. Their dimensions are about 3-5 cm, weight is less than 50-60 g. They gained immense popularity and distribution after 2000 due to their compactness, ease of overwriting files, large memory, and reliable case. The main purpose of USB drives is storage, backup, transfer and exchange of data, loading operating systems (LiveUSB), etc.

Usually this device has a characteristic elongated shape, has a removable cap covering the connector. A flash drive can be worn with a cord or chain around the neck, in a pocket, on a belt, in a bag. Modern flash drives have a variety of shapes and sizes, ways to protect the connector. They can have both a “non-standard” appearance (a toy, an army knife, a watch) and additional features (in particular, fingerprint verification).

We figured out what a flash drive is above, but it is important to know that in order to extend the life of representatives of the flash memory family (USB flash drives, memory cards, removable hard drives), a number of certain rules should be observed:

1. Although the USB interface allows hot plugging, always use a feature such as "Safely Remove Hardware". To do this, you need to use the corresponding icon located in the notification area (on the right side), by clicking on it with the left mouse button. Then you need to select "Safely Remove USB Devices" from the context menu. Before the procedure, you must close the files from the flash drive.
2. You need to be careful with your flash drive. Do not expose it to shock, strong electromagnetic fields, high temperatures or moisture.
3. Do not remove the flash drive from the computer while accessing it, as this can damage the device and lose data. If at the time of disconnecting your flash drive from the PC, a recording was in progress, then errors will appear in the file system of the flash drive. The flash drive should be completely formatted. To do this, you need to open My Computer, right-click on the flash drive icon, call the context menu, select "Format". In the Format Removable Disk window, click the Start button, then OK. Do not forget to first copy all the data from the flash drive to the computer's hard drive before formatting!

Recommend:

1. In connection with the emergence of viruses designed to destroy existing information on flash drives, if you need to copy information from your flash drive to someone else's PC, prudently enable write blocking (if such is provided by the design of the flash drive).
2. It happens that flash drives are poorly recognized when they are connected to the USB ports on the front of the PC. Try connecting them to the ports on the back panel.

If you are interested in the security of your data on flash drives, you can read the articles "" and "".

Since a flash drive is perhaps the most popular and massively widespread data carrier, there is a danger of a large number of a wide variety of computer viruses spreading through flash memory. You need to secure your computer. To do this, disable autorun (autoload). Use reliable antiviruses, use fingerprint-enabled flash drives, use flash drives with effective write protection.

An effective means of protection against all kinds of viruses will be the use of the NTFS file system with the creation of directories for writing files, protecting the root directory of your flash drive. All this, of course, cannot guarantee complete protection, since the user must carefully "filter" the data himself (do not download information from suspicious flash drives, CDs, DVDs, websites, etc.).

Do not rush to throw away your flash drive if it is not visible to the system, reads with errors, is buggy and you cannot write anything to it. There are a number of quite effective programs for recovering flash drives. Programs such as JetFlash Recovery Tool, D-Soft Flash Doctor, EzRecover, F-Recovery for CompactFlash and others can help you. They will help you recover text files, photos, music." In a few minutes, you can get a full-fledged working flash drive.

If you urgently need data, and the memory card or flash drive is broken, then you should not be discouraged in this case either. Reliable recovery of any data from a flash memory carrier is quite possible even in cases of physical failure. It is possible to save information and copy data from the affected flash drive, but if you physically broke it, it is already impossible. You also need to know that there are a number of points when restoring information that must be observed. The flash drive recovery method will depend on the type of malfunction (damage to the electronic part, physical damage, logical data violations).

The times of diskettes are irrevocably a thing of the past. Compact, quiet, durable and stylish, flash drives are now actively replacing disks. They are convenient, versatile, aesthetic (there are advertising and gift flash drives, decorated with rhinestones, with inscriptions and logos applied by a solid-state laser). Flash drives have firmly entered the life of a modern person.

And now let's see how flash drives are made: