What digital media do you know. Disk media. What are storage media

Information carrier- the physical environment directly storing information. The main carrier of information for a person is his own biological memory (human brain). A person's own memory can be called working memory. Here the word "operational" is synonymous with the word "fast". Learned knowledge is reproduced by a person instantly. We can also call our own memory internal memory, since its carrier - the brain - is inside us.

Information carrier- a strictly defined part of a particular information system, which serves for intermediate storage or transmission of information.

The basis of modern information technologies- It's a computer. When it comes to computers, we can talk about storage media as external storage devices (external memory). These data carriers can be classified according to various features, for example, according to the type of execution, the material from which the carrier is made, etc. Here is one of the options for classifying media:

Tape media

Magnetic tape- a magnetic recording medium, which is a thin flexible tape consisting of a base and a magnetic working layer. The working properties of a magnetic tape are characterized by its sensitivity during recording and signal distortion during recording and playback. The most widely used is a multilayer magnetic tape with a working layer of needle-shaped particles of magnetically hard powders of gamma-iron oxide (y-Fe2O3), chromium dioxide (CrO2) and gamma-iron oxide modified with cobalt, usually oriented in the direction of magnetization during recording.

Disk media refer to machine media with direct access. The concept of direct access means that the PC can “access” the track on which the section with the required information begins or where new information needs to be written.

Disk drives are the most diverse:

Floppy disk drives (FPHD), they are also floppy disks, they are also floppy disks

Hard disk drives (HDD), they are also hard drives (popularly just "screws")

Optical CD drives:

• CD-ROM (Compact Disk ROM)

In floppy disk drives (NGMD or floppy disks) and hard disk drives (HDD or hard drives), the basis for recording, storing and reading information is the magnetic principle, and in laser disk drives - the optical principle.

Flexible magnetic disks placed in a plastic case. This storage medium is called a floppy disk. A floppy disk is inserted into a disk drive that rotates the disk at a constant angular velocity. The magnetic head of the drive is installed on a certain concentric track of the disk, on which information is written (or read).

The information capacity of a floppy disk is small and amounts to only 1.44 MB. The speed of writing and reading information is also low (about 50 KB / s) due to the slow rotation of the disk (360 rpm).

Hard magnetic disks.

Hard disk (HDD - Hard Disk Drive) refers to non-replaceable disk magnetic drives. The first HDD was developed by IBM in 1973 and had a capacity of 16 KB. Hard magnetic disks are several dozens of disks placed on the same axis, enclosed in a metal case and rotating at a high angular speed. The speed of writing and reading information from hard disks is quite high (about 133 MB / s) due to the fast rotation of disks (7200 rpm).

Failures occur during the operation of the computer. Viruses, power outages, software errors - all this can cause damage to the information stored on your hard drive. Damage to information does not always mean loss of it, so it is useful to know how it is stored on the hard drive, because then it can be restored. Then, for example, if the boot area is damaged by a virus, it is not at all necessary to format the entire disk (!), but, after restoring the damaged area, continue normal work with the preservation of all your priceless data.

Hard disks use rather fragile and miniature elements. To preserve the information and performance of hard drives, it is necessary to protect them from shocks and sudden changes in spatial orientation during operation.

Laser drives and disks.

In the early 80s, the Dutch company Philips announced a revolution in the field of sound reproduction. Its engineers came up with something that is now very popular - These are laser discs and players.

Laser disk drives use the optical principle of reading information. On CD (CD - Compact Disk, compact disc) and DVD (DVD - Digital Video Disk, digital video disc) laser discs, information is recorded on one spiral track (like on a gramophone record) containing alternating sections with different reflectivity. The laser beam falls on the surface of a rotating disk, and the intensity of the reflected beam depends on the reflectivity of the track section and takes on the values ​​0 or 1. To preserve information, laser disks must be protected from mechanical damage (scratches), as well as from contamination. Laserdiscs store information that was recorded on them during the manufacturing process. Writing new information to them is not possible. Such discs are produced by stamping. There are CD-Rs and DVD-R discs information on which can be recorded only once. On CD-RW and DVD-RW discs, information can be written/overwritten multiple times. Disks different types can be distinguished not only by markings, but also by the color of the reflective surface.

Flash based devices.

Flash memory is a non-volatile type of memory that allows data to be written and stored on chips. Devices based on flash-memory have no moving parts, which ensures high data safety when used in mobile devices.

Flash memory is a microchip placed in a miniature package. To write or read information, the drives are connected to a computer via a USB port. The information capacity of memory cards reaches 1024 MB.

“So that you live in an era of change” is a very laconic and quite understandable curse for a person, say, over 30 years old. The current stage of human development has made us unwitting witnesses of a unique "epoch of change". And even here it’s not just the scale of modern scientific progress that plays a role, in terms of significance for civilization, the transition from stone tools to copper was obviously much more significant than doubling the computing capabilities of the processor, which in itself will be clearly more technologically advanced. That huge, ever-increasing rate of change in the technical development of the world is simply discouraging. If a hundred years ago, every self-respecting gentleman simply had to be aware of all the "novelties" in the world of science and technology, so as not to look like a fool and a redneck in the eyes of his environment, now, given the volume and speed of the generation of these "novelties", it is completely easy to track them impossible, even the question is not put like that. The inflation of technologies, not even recently conceivable, and the human capabilities associated with them, have actually killed a wonderful trend in literature - "Technical fiction". There is no longer a need for it, the future has become many times closer than ever, the planned story about the “wonderful technology” risks reaching the reader later than something like this will already roll off the assembly lines of the research institute.

The progress of human technical thought has always been displayed most quickly in the field of information technology. Ways of collecting, storing, systematizing, disseminating information run like a red thread through the entire history of mankind. Breakthroughs, whether in the field of technical sciences or the humanities, one way or another, responded to IT. The civilizational path passed by mankind is a series of successive steps to improve the ways of storing and transmitting data. In this article, we will try to understand and analyze in more detail the main stages in the development of information carriers, to conduct their comparative analysis, starting from the most primitive - clay tablets, up to the latest successes in creating a machine-brain interface.

The task set is really not a joke, you see what you swung at, an intrigued reader will say. It would seem, how is it possible, subject to at least elementary correctness, to compare the technologies of the past and today that differ significantly from each other? Contribute to the solution of this issue may be the fact that the ways of perceiving information by a person are actually not strong and have changed. Forms of recording and reading information by means of sounds, images and coded symbols (letters) remained the same. In many ways, it is this givenness that has become, so to speak, a common denominator, thanks to which it will be possible to make qualitative comparisons.

Methodology

To begin with, it is worth resurrecting the common truths in memory, with which we will continue to operate. The elementary information carrier of the binary system is a “bit”, while the minimum unit of data storage and processing by a computer is a “byte”, while in standard form, the latter includes 8 bits. A more familiar megabyte for our hearing corresponds to: 1 MB = 1024 KB = 1048576 bytes.

Reduced units per this moment are universal measures of the amount of digital data placed on a particular medium, so they will be very easy to use in future work. Universality lies in the fact that a group of bits, in fact, a cluster of numbers, a set of values ​​1 / 0, can describe any material phenomenon and thereby digitize it. It does not matter whether it is the most sophisticated font, a picture, a melody, all these things consist of separate components, each of which is assigned its own unique digital code. Understanding this basic principle makes it possible for us to move forward.

Heavy, analogue childhood of civilization

The very evolutionary formation of our species threw people into the embrace of the analog perception of the space around them, which in many respects predetermined the fate of our technological formation.

At the first glance of a modern person, the technologies that originated at the very dawn of mankind are very primitive, for those who are not versed in details, the very existence of mankind before the transition to the era of "digits" may seem like this, but is it really so, was it really such a "childhood" was difficult? Having asked ourselves to study the question posed, we can see very unpretentious technologies for storing and processing information at the stage of their appearance. The first information carrier of its kind, created by man, were portable areal objects with images printed on them. Tablets and parchments made it possible not only to store, but also to process this information more efficiently than ever before. At this stage, the opportunity to concentrate a huge amount of information in specially designated places - storages, where this information was systematized and carefully guarded, became the main impetus to the development of all mankind.

The first known data centers, as we would call them now, until recently called libraries, arose in the vastness of the Middle East, between the rivers Nile and Euphrates, about the 2nd millennium BC. The very format of the information carrier all this time significantly determined the ways of interacting with it. And here it is not so important whether it is an adobe tablet, a papyrus scroll, or a standard A4 paper sheet, all these thousands of years have been closely united by the analog method of entering and reading data from the carrier.

The period of time during which it was the analog way of human interaction with his informational belongings that dominated has successfully lasted into the flesh to the present day, only quite recently, already in the 21st century, finally giving way to the digital format.

Having outlined the approximate time and semantic framework of the analog stage of our civilization, we can now return to the question posed at the beginning of this section, after all, these data storage methods are not effective, which we had and until very recently used, not knowing about the iPad, flash drives and optical discs?

Let's do the calculation

If we discard the last stage of the decline of analog data storage technologies, which lasted for the last 30 years, we can note with regret that these technologies themselves, by and large, have not undergone significant changes for thousands of years. Indeed, a breakthrough in this area took place relatively recently, this is the end of the 19th century, but more on that below. Until the middle of the declared century, among the main ways of recording data, two main ones can be distinguished, these are writing and painting. The essential difference between these methods of information registration, absolutely regardless of the medium on which it is carried out, lies in the logic of information registration.

art

Painting seems to be the most in a simple way data transfer that does not require any additional knowledge, both at the stage of creation and use of data, thereby actually being the original format perceived by a person. The more accurately the reflected light from the surface of surrounding objects is transmitted to the retina of the scribe's eye on the surface of the canvas, the more informative this image will be. The lack of thoroughness of the transmission technique, the materials used by the creator of the image, are the noise that will further interfere with the accurate reading of the information recorded in this way.

How informative is the image, what quantitative value of information is the drawing. At this stage of understanding the process of transmitting information in a graphical way, we can finally plunge into the first calculations. This is where a basic computer science course comes in handy.

Any raster image is discrete, it's just a whole set of points. Knowing this property of it, we can translate the displayed information that it carries into units understandable to us. Since the presence / absence of a contrast point is actually the simplest binary code 1 / 0, then, therefore, each of this point acquires 1 bit of information. In turn, the image of a group of dots, say 100x100, will contain:

V = K * I = 100 x 100 x 1 bit = 10,000 bits / 8 bits = 1250 bytes / 1024 = 1.22 kbytes

But let's not forget that the above calculation is correct only for a monochrome image. In the case of much more frequently used color images, naturally, the amount of information transmitted will increase significantly. If we accept 24-bit (photographic quality) encoding as a condition for sufficient color depth, and, let me remind you, it has support for 16,777,216 colors, then we will get a much larger amount of data for the same number of points:

V = K * I = 100 x 100 x 24 bits = 240,000 bits / 8 bits = 30,000 bytes / 1024 = 29.30 kbytes

As you know, a point has no size, and in theory, any area allotted for drawing an image can carry an infinite amount of information. In practice, there are well-defined sizes and, accordingly, you can determine the amount of data.

Based on many studies, it was found that a person with average visual acuity, from a comfortable distance for reading information (30 cm), can distinguish about 188 lines per 1 centimeter, which in modern technology approximately corresponds to the standard image scanning parameter of household scanners at 600 dpi . Therefore, from one square centimeter of the plane, without additional devices, the average person can count 188:188 points, which will be equivalent to:

For a monochrome image:
Vm = K * I = 188 x 188 x 1 bit = 35344 bits / 8 bits = 4418 bytes / 1024 = 4.31 kbytes

For a photographic quality image:
Vc = K * I = 188 x 188 x 24 bits = 848,256 bits / 8 bits = 106,032 bytes / 1024 = 103.55 kbytes

For greater clarity, based on the calculations obtained, we can easily establish how much information such a familiar sheet of format as A4 with dimensions of 29.7 / 21 cm carries in itself:

VA4 = L1 x L2 x Vm = 29.7 cm x 21 cm x 4.31 KB = 2688.15 / 1024 = 2.62 MB - monochrome image

VA4 = L1 x L2 x Vm = 29.7 cm x 21 cm x 103.55 KB = 64584.14 / 1024 = 63.07 MB - color image

Writing

If with fine arts The “picture” is more or less clear, but writing is not so simple. The obvious differences in the ways of transferring information between text and drawing dictate a different approach in determining the information content of these forms. Unlike an image, writing is a type of standardized, coded communication. Without knowing the code of words embedded in the letter and the letters that form them, the informative load, say, of Sumerian cuneiform, for most of us is generally equal to zero, while ancient images on the ruins of the same Babylon will be quite correctly perceived even by a person who is absolutely ignorant of the intricacies of the ancient world . It becomes quite obvious that the information content of the text depends extremely strongly on whose hands it fell into, on its deciphering by a specific person.

Nevertheless, even under such circumstances, which somewhat blur the validity of our approach, we can quite unambiguously calculate the amount of information that was placed in texts on various flat surfaces.
By resorting to the binary coding system already familiar to us and the standard byte, written text, which can be imagined as a set of letters that form words and sentences, can be very easily reduced to the digital form 1 / 0.

The usual 8-bit byte for us can acquire up to 256 different digital combinations, which should actually be enough for a digital description of any existing alphabet, as well as numbers and punctuation marks. Hence the conclusion suggests itself that any standard character of alphabetic writing applied to the surface takes 1 byte in digital equivalent.

The situation is slightly different with hieroglyphs, which have also been widely used for several thousand years. Replacing a whole word with one character, this encoding clearly uses the plane assigned to it much more efficiently in terms of information load than it happens in languages ​​based on the alphabet. At the same time, the number of unique characters, each of which must be assigned a non-repeated combination of a combination of 1 and 0, is many times greater. In the most common existing hieroglyphic languages: Chinese and Japanese, according to statistics, no more than 50,000 unique characters are actually used, in Japanese and even less, at the moment the country's Ministry of Education, for everyday use, has identified only 1850 hieroglyphs. In any case, 256 combinations that fit into one byte are no longer enough here. One byte is good, and two is even better, says the modified folk wisdom, 65536 - that is how many digital combinations we get using two bytes, which, in principle, becomes sufficient to translate an actively used language into digital form, thereby assigning two bytes to the absolute majority of hieroglyphs.

The current practice of using letters tells us that about 1800 readable, unique signs can be placed on a standard A4 sheet. Having carried out simple arithmetic calculations, it is possible to establish how much information one standard typewritten sheet of alphabetic, and more informative hieroglyphic writing will carry in digital terms:

V \u003d n * I \u003d 1800 * 1 byte \u003d 1800 / 1024 \u003d 1.76 kbytes or 2.89 bytes / cm2

V = n * I = 1800 * 2 bytes = 3600 / 1024 = 3.52 kb or 5.78 bytes/cm2

industrial leap

The 19th century was a turning point, both for the methods of recording and storing analog data, this was the result of the emergence of revolutionary materials and methods for recording information, which were to change the IT world. One of the main innovations was the sound recording technology.

The invention of the phonograph by Thomas Edison first gave rise to the existence of cylinders with grooves applied to them, and soon also of records - the first prototypes of optical discs.

Responding to sound vibrations, the phonograph cutter tirelessly made grooves on the surface of both metal and, a little later, polymer. Depending on the captured vibration, the cutter made a swirling groove of different depths and widths on the material, which in turn made it possible to record sound and reproduce, in a purely mechanical way, the already engraved sound vibrations back.

At the presentation of the first phonograph by T. Edison at the Paris Academy of Sciences, there was an embarrassment, one not young, linguist, almost hearing a reproduction of human speech by a mechanical device, took off from his seat and indignantly rushed with his fists at the inventor, accusing him of fraud. According to this respected member of the academy, metal could never repeat the melodiousness of the human voice, and Edison himself is an ordinary ventriloquist. But we know that this is certainly not the case. Moreover, in the 20th century, people learned how to store sound recordings in digital format, and now we will plunge into some numbers, after which it will become quite clear how much information fits on an ordinary vinyl record (the material has become the most characteristic and mass representative of this technology) record.

In the same way as before with the image, here we will start from the human ability to capture information. It is widely known that most often the human ear is able to perceive sound vibrations from 20 to 20,000 Hertz, based on this constant, a value of 44100 Hertz was adopted for the transition to a digital sound format, since for a correct transition, the sampling frequency of the sound vibration must be in twice its original value. Also, an important factor here is the depth of encoding of each of the 44100 vibrations. This parameter directly affects the number of bits inherent in one wave, the greater the position of the sound wave is recorded in a particular second of time, the more bits it must be encoded and the better the digitized sound will sound. The ratio of sound parameters chosen for the most common today's format, not distorted by the compression used on audio discs, is its 16-bit depth, with a resolution of oscillations of 44.1 kHz. Although there are more “capacious” ratios of the given parameters, up to 32bit / 192kHz, which could be more comparable with the actual sound quality of a gram recording, but we will include the ratio of 16bit / 44.1kHz in the calculations. It was the chosen ratio in the 80-90s of the twentieth century that dealt a crushing blow to the analog audio recording industry, becoming in fact a full-fledged alternative to it.

And so, taking the announced values ​​as the initial sound parameters, we can calculate the digital equivalent of the volume of analog information that the recording technology carries:

V = f * I = 44100 Hertz * 16 bits = 705600 bps / 8 = 8820 bytes/s / 1024 = 86.13 kbps

By calculation, we obtained the necessary amount of information to encode 1 second of the sound of a high-quality recording. Since the dimensions of the plates varied, just like the density of the grooves on its surface, the amount of information on specific representatives of such a carrier also differed significantly. The maximum time for high-quality recording on a vinyl record with a diameter of 30 cm was less than 30 minutes on one side, which was at the limit of the material's capabilities, but usually this value did not exceed 20-22 minutes. With this characteristic, it follows that the vinyl surface could accommodate:

Vv = V * t = 86.13 kbps * 60 sec * 30 = 155034 kb / 1024 = 151.40 mb

But in fact, no more than:
Vvf = 86.13 kb/sec * 60 sec * 22 = 113691.6 kb / 1024 = 111.03 mb

The total area of ​​such a plate was:
S = π* r^2 = 3.14 * 15 cm * 15 cm = 706.50 cm2

In fact, there are 160.93 kb of information per square centimeter of a disc, naturally, the proportion for different diameters will not change linearly, since here we take not the effective recording area, but the entire carrier.

Magnetic tape

The last and, perhaps, the most effective data carrier applied and read by analog methods has become a magnetic tape. Tape is actually the only medium that has survived the analog era quite successfully.

The very technology of recording information by the method of magnetization was patented at the end of the 19th century by the Danish physicist Voldemar Poultsen, but unfortunately, then it did not become widespread. For the first time, the technology on an industrial scale was used only in 1935 by German engineers, on its basis the first tape recorder was created. For 80 years of its active use, magnetic tape has undergone significant changes. Different materials were used, different geometric parameters of the tape itself, but all these improvements were based on a single principle, developed back in 1898 by Poultsen, magnetic registration of oscillations.

One of the most widely used formats was a tape consisting of a flexible base on which one of the metal oxides (iron, chromium, cobalt) was deposited. The width of the tape used in consumer audio tape recorders was usually one inch (2.54 cm), the thickness of the tape started from 10 microns, as for the length of the tape, it varied significantly in different coils and most often ranged from hundreds of meters to a thousand. For example, a reel with a diameter of 30 cm could hold about 1000 m of tape.

The sound quality depended on many parameters, both the tape itself and the equipment that read it, but in general, with the right combination of these same parameters, it was possible to make high-quality studio recordings on a magnetic tape. Higher sound quality was achieved by using a larger volume of tape to record a unit of sound time. Naturally, the more tape is used to record the moment of sound, the wider the range of frequencies managed to be transferred to the media. For high-quality studio materials, the recording speed on the tape was at least 38.1 cm/sec. When listening to recordings in everyday life, a recording made at a speed of 19 cm / s was enough for a sufficiently complete sound. As a result, a 1000 m reel could accommodate up to 45 minutes of studio sound, or up to 90 minutes of content acceptable to the bulk of consumers. In the case of technical recordings or speeches, for which the width of the frequency range during playback did not play a special role, with a tape consumption of 1.19 cm / s per reel, it was possible to record sounds for as long as 24 hours.

Having a general idea of ​​​​the technologies of recording on magnetic tape in the second half of the twentieth century, it is possible to more or less correctly convert the capacity of reel-to-reel media into units of measurement of data volume that we understand, as we have already done for recording.

In a square centimeter of such a carrier will be placed:
Vo = V / (S * n) = 86.13 kb/s / (2.54 cm * 1 cm * 19) = 1.78 kb/cm2

Total reel volume with 1000 meters of film:
Vh = V * t = 86.13 kbps * 60 sec * 90 = 465102 kb / 1024 = 454.20 MB

Do not forget that the specific footage of the tape in the reel was very different, it depended, first of all, on the diameter of the reel and the thickness of the tape. Quite common, due to acceptable dimensions, reels were widely used, containing 500 ... 750 meters of film, which for an ordinary music lover was the equivalent of an hour-long sound, which was quite enough to cover an average music album.

Quite short, but no less bright was the life of video cassettes, which used the same principle of recording an analog signal on magnetic tape. By the time this technology was used commercially, the recording density on magnetic tape had increased dramatically. On a half-inch film 259.4 meters long, 180 minutes of video material with a very dubious quality, as today, fit in. The first video recording formats produced a picture at the level of 352x288 lines, the best samples showed the result at the level of 352x576 lines. In terms of bitrate, the most progressive recording playback methods made it possible to approach the value of 3060 kbit / s, with a speed of reading information from the tape at 2.339 cm / s. On a standard three-hour cassette, about 1724.74 MB could fit, which is generally not so bad, as a result, video cassettes remained massively in demand until very recently.

magic number

The appearance and widespread introduction of numbers (binary coding) is entirely due to the twentieth century. Although the philosophy of coding binary code 1 / 0, Yes / No, one way or another hovered among mankind at different times and on different continents, sometimes gaining the most amazing forms, it finally materialized precisely in 1937. MIT student Claude Shannon, based on the work of the great British (Irish) mathematician George Boulet, applied the principles of Boulein algebra to electrical circuits, which in fact became the starting point for cybernetics in the form in which we know it now.

In less than a hundred years, both the hardware and software components of digital technology have undergone a huge number of major changes. The same is true for information carriers. Starting from super inefficient - paper digital data carriers, we have come to super efficient - solid state storage. In general, the second half of the last century passed under the banner of experiments and the search for new forms of media, which can be succinctly called the general mess of the format.

Card

Punched cards have become, perhaps, the first step on the path of interaction between computers and humans. Such communication lasted quite a long time, sometimes even now this carrier can be found in specific research institutes scattered throughout the CIS.

One of the most common punched card formats was the IBM format introduced back in 1928. This format became the base for the Soviet industry. The dimensions of such a punched card according to GOST were 18.74 x 8.25 cm. No more than 80 bytes could fit on a punched card, only 0.52 bytes per 1 cm2. In this calculation, for example, 1 Gigabyte of data would be equal to approximately 861.52 Hectares of punched cards, and the weight of one such Gigabyte would be slightly less than 22 tons.

Magnetic tapes

In 1951, the first samples of data carriers based on the technology of pulsed magnetization of the tape were released specifically for registering “numbers” on it. This technology made it possible to insert up to 50 characters per centimeter of a half-inch metal tape. In the future, the technology has been seriously improved, allowing many times to increase the number of single values ​​per unit area, as well as to reduce the cost of the material of the carrier itself as much as possible.

At the moment, according to the latest statements by Sony Corporation, their nano-developments allow placing the amount of information per 1 cm2 equal to 23 Gigabytes. Such ratios of numbers suggest that this technology of tape magnetic recording has not outlived itself and has rather bright prospects for further exploitation.

Gram record

Probably the most surprising method of storing digital data, but only at first glance. The idea of ​​recording a live program on a thin layer of vinyl came up in 1976 at Processor Technology, which was based in Kansas City, USA. The essence of the idea was to reduce the cost of the storage medium as much as possible. The company's employees took an audio tape with recorded data in the already existing Kansas City Standard sound format and distilled it onto vinyl. In addition to reducing the cost of the media, this solution made it possible to hem the engraved plate to a regular magazine, which made it possible to distribute small programs in large quantities.

In May 1977, magazine subscribers were the first to receive a disc in their issue, which housed a 4K BASIC interpreter for the Motorola 6800 processor. The record played for 6 minutes.
This technology, for obvious reasons, did not take root, officially, the last disc, the so-called Floppy-Rom, was released in September 1978, it was its fifth release.

Winchesters

The first hard drive was introduced by IBM in 1956, the IBM 350 model came with the company's first mass-produced computer. The total weight of such hard drive"was 971 kg. In terms of dimensions, it was akin to a closet. It contained 50 disks, the diameter of which was 61 cm. The total amount of information that could fit on this "hard drive" was a modest 3.5 megabytes.

The very technology of data recording was, if I may say so, a derivative of record and magnetic tapes. The disks placed inside the case stored a lot of magnetic pulses that were applied to them and read by the movable head of the recorder. Like a gramophone top, at each moment of time, the registrar moved over the area of ​​each of the disks, gaining access to the required cell, which carried a magnetic vector of a certain direction.

At the moment, the aforementioned technology is also alive and, moreover, is actively developing. Less than a year ago, Western Digital launched the world's first 10TB hard drive. In the middle of the body there were 7 plates, and instead of air, helium was pumped into the middle of it.

Optical discs

They owe their appearance to the partnership of two corporations Sony and Philips. The optical disc was introduced in 1982 as a viable digital alternative to analog audio media. With a diameter of 12 cm, up to 650 MB could be placed on the first samples, which, with a sound quality of 16 bit / 44.1 kHz, was 74 minutes of sound and this value was not chosen in vain. It is 74 minutes that Beethoven's 9th symphony lasts, which was overly loved either by one of the co-owners of Sony, or by one of the developers from Philips, and now it could fit entirely on one disc.

The technology of the process of applying and reading information is very simple. Indentations are burned on the mirror surface of the disk, which, when information is read out optically, are unambiguously registered as 1 / 0.

Optical media technology is also booming in our 2015. The technology known to us as a four-layer Blu-ray disc holds about 111.7 gigabytes of data on its surface, at its not too high price, being ideal media for very "capacious" high-resolution films with deep color reproduction.

Solid state drives, flash memory, SD cards

All this is the brainchild of one technology. The principle of data recording developed back in the 1950s based on the registration of an electric charge in an isolated region of a semiconductor structure. For a long time he did not find his practical implementation to create a full-fledged information carrier on its basis. The main reason for this was the large dimensions of transistors, which, with their maximum possible concentration, could not generate a competitive product on the data carrier market. The technology was remembered and periodically tried to introduce it during the 70s-80s.

The real high point for solid-state drives has come since the late 80s, when the size of semiconductors began to reach acceptable sizes. Japanese Toshiba in 1989 presented a completely new type of memory "Flash", from the word "Flash". This word itself very well symbolized the main pros and cons of media implemented on the principles of this technology. Unprecedented speed of access to data, a rather limited number of rewrite cycles and the need for an internal power supply for some of this kind of media.

To date, the largest concentration of memory storage media manufacturers have achieved thanks to the SDCX card standard. With dimensions of 24 x 32 x 2.1 mm, they can support up to 2 TB of data.

Cutting edge of scientific progress

All the media that we have dealt with up to this point have been from the world of non-animal nature, but let's not forget that the very first store of information that we all have dealt with is the human brain.

The principles of the functioning of the nervous system in general terms are already clear today. And no matter how surprising it may sound, the physical principles of the brain are quite comparable with the principles of organization of modern computers.
A neuron is a structurally functional unit of the nervous system, it forms our brain. A microscopic cell of a very complex structure, which is actually an analogue of the transistor we are used to. The interaction between neurons occurs due to various signals that propagate with the help of ions, which in turn generate electrical charges, thus creating an unusual electrical circuit.

But even more interesting is the very principle of the neuron, like its silicon counterpart, this structure oscillates on the binary position of its state. For example, in microprocessors, the difference in voltage levels is taken as a conditional 1 / 0, the neuron, in turn, has a potential difference, in fact, at any time it can acquire one or two possible polarity values: either “+” or “-”. The essential difference between a neuron and a transistor is the limiting speed of the first to acquire opposite values ​​1 / 0. As a result of its structural organization, which we will not go into too much detail, a neuron is thousands of times more inert than its silicon counterpart, which naturally affects its speed - the number processing requests per unit of time.

But not everything is so sad for living beings, unlike a computer where the processes are executed in a sequential mode, billions of neurons united in the brain solve the tasks in parallel, which gives whole line benefits. Millions of these low-frequency processors quite successfully make it possible, in particular for a person, to interact with the environment.

Having studied the structure of the human brain, the scientific community came to the conclusion that, in fact, the brain is an integral structure, which already includes a computing processor, instant memory, and long-term memory. By virtue of the very neural structure of the brain, there are no clear, physical boundaries between these hardware components, only blurry zones of specification. This statement is confirmed by dozens of precedents from life, when, due to certain circumstances, part of the brain was removed from people, up to half of the total volume. Patients after such interventions, in addition to not turning into a “vegetable”, in some cases, over time, restored all their functions and happily lived to a ripe old age, thus being living proof of the depth of flexibility and perfection of our brain.

Returning to the topic of the article, we can come to an interesting conclusion: the structure of the human brain is actually similar to the solid state drive of information, which was discussed a little higher. After such a comparison, keeping in mind all its simplifications, we can ask ourselves, how much data can be placed in this storage in this case? Maybe again, surprisingly, but we can get a completely unambiguous answer, let's do the calculation.

As a result of scientific experiments conducted in 2009 by a neuroscientist, doctor of the Brazilian University in Rio de Janeiro - Susanna Herculano-Hauzel, it was found that on average human brain, weighing about one and a half kilograms, you can count approximately 86 billion neurons, let me remind you that earlier scientists believed that this figure for the average value is equal to 100 billion neurons. Based on these numbers and equating each individual neuron to actually one bit, we get:

V = 86,000,000,000 bits / (1024 * 1024*1024) = 80.09 Gb / 8 = 10.01 Gb

Is it a lot or a little, and how much can this medium for storing information be a competitor? It is still very difficult to say. Every year, the scientific community pleases us more and more with progress in the study of the nervous system of living organisms. You can even come across references to the artificial introduction of information into the memory of mammals. But by and large, the secrets of brain thinking are still a mystery to us.

Outcome

Although not all types of data carriers, of which there are a huge number, were presented in the article, the most typical representatives found a place in it. Summing up the presented material, one can clearly trace the pattern - the entire history of the development of data carriers is based on the heredity of the stages preceding the current moment. The progress of the last 25 years in the field of storage media is firmly based on the experience gained from at least the last 100-150 years, while the growth rate of storage capacity over these quarter of a century is increasing exponentially, which is a unique case throughout the entire known history of mankind.

Despite the archaism of analog data recording that seems to us now, until the end of the 20th century it was a completely competitive method of working with information. An album with high-quality images could contain gigabytes of the digital equivalent of data that, until the early 1990s, was simply physically impossible to place on such a compact medium, not to mention the absence of acceptable ways to work with such data arrays.

The early sprouts of optical disc recording and the rapid development of HDD storage in the late 1980s broke the competition of many analog recording formats in just one decade. Although the first musical optical discs did not differ qualitatively from the same vinyl records, having 74 minutes of recording versus 50-60 (double-sided recording), but the compactness, versatility and further development of the digital direction are expected, finally buried the analog format for mass use.

The new era of information carriers, on the threshold of which we are standing, can significantly affect the world in which we find ourselves in 10 ... 20 years. Already, advanced work in bioengineering gives us the opportunity to superficially understand the principles of operation of neural networks, to control certain processes in them. While the potential for placing data on structures similar to the human brain is not that great, there are things that should not be forgotten. The very functioning of the nervous system is still rather mysterious, as a result of its little study. The principles of placing and storing data in it, already at the first approximation, it is obvious that they operate according to a slightly different law than it would be true for the analog and digital method of information processing. As in the transition from the analog stage of human development to the digital one, in the transition to the era of the development of biological materials, the two previous stages will serve as a foundation, a kind of catalyst for the next leap. The need for activation in the bioengineering direction was obvious even earlier, but only now the technological level of human civilization has risen to the level where such work can really be crowned with success. Whether this new stage in the development of IT technologies will absorb the previous stage, as we have already had the honor to observe, or whether it will go in parallel, it is too early to predict, but it is obvious that it will radically change our lives.

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In the era of high technology, data storage and access is one of the important factors person. For a simple user, his home photos and videos are important data, especially photos and shootings of significant dates, but favorite collections of music and films also play an important role. For people whose computer is not only an entertainment center, but also helps in daily work, important data are electronic office files that help to eliminate paper routine work.

We often forget about what and how is stored on the computer, because the workflow is completely automated. But unfortunately, the sources of electronic information storage are far from ideal and, as a rule, fail at the most inopportune moment for us.

So what are modern media? Probably almost every computer user uses HDD, as the main storage for data files. This is a high-tech device, which is a small iron box, completely sealed, in which there is a magnetic disk several millimeters thick. Usually, an electronic head reads information floating at a micron distance from the disk from below or above. The rotation speed of the disc is about 10,000 rpm. Any microscopic speck of dust that has fallen on the surface of a magnetic disk will almost immediately cause the entire “hard drive” (another name for a hard disk) to fail. And this is only one of the few reasons that can cause the rapid death of this digital medium. In fact, a hard drive failure can cause even an elementary power surge.

The very first storage medium that everyone remembers was the laser CD. Then we looked with surprise at this brilliant " kruglyash and puzzled over how it contained a collection of our favorite music. By the way, for certain reasons, this carrier still does not lose its relevance. First of all, probably because of their small size and conditional price - now in any store there are empty "blanks" " CD" or " DVD” for recording, you can buy almost free. Another reason for the survivability of these media lies in the convenient use of them to create information products by companies involved in the development of software to this or that electronic device such as a printer, scanner, digital camera, and the like. Or use CDs to create your own music and films. It is very convenient to capture your "masterpieces" in the form of electronic files recorded on a laser disc, placed in a beautiful box, with a detailed indication of the disc menu and other features. Moreover, the cost of such packaging is scanty.

The laser disk consists of several layers connected together: the first, lower one is made of polycarbonate, the second is made of thin aluminum, it is on it that information is stored, the third is a protective layer, a conventional varnish coating with a label. This is the standard structure CD» disk, « DVD»consists of similar layers, only usually there are many more of them, and they are better protected. That is why it is preferable to store information on " DVD» disks than on « CD". In addition, the volume of the latter is 6-7 times less.

The most common carrier, or even more precisely, the “store” of information, at the moment is the well-known “flash drive”. " USB flash drive"consists of electronic microcircuits capable of holding charges (electrons), which contain information. This is the most convenient carrier for the average user, since its dimensions are minimal. A flash drive is used in almost all modern devices, even such as TVs and radios. The main disadvantage of this drive is its short life. You can write information to it about 10,000 times, then this device usually no longer works or malfunctions.

Along with flash drives in terms of frequency of use, there are also portable media, small boxes that connect to the port " USB» computer and have a volume of 80 to 1000 gigabytes and above. Many people think that these are the same flash drives, only with a larger volume. But if we open such a device, we will see inside a regular laptop hard drive, which is connected to our computer through a kind of “bridge”. In fact, this is the same hard drive, and since its dimensions are miniature to fit freely in a laptop, the system is more at risk than the “hard drive” of a personal computer.

Recently, solid-state hard drives have appeared on the computer accessories market. The data reading speed of such devices is several times higher than that of a conventional computer hard drive. It is because of their speed that they have become so widespread. But such disks are not cheap, and for a simple layman who is very limited by the budget, when assembling his computer, they are unlikely to fit. Yes, and there are many disadvantages of such devices. Since they consist of the same microcircuits as on " USB flash drive, and their life expectancy is short. Although it must be admitted that the future belongs to these small devices, but they still need more than one year to finalize.

So what kind of drive should a simple user choose to store their home photos or a collection of music with movies? It's hard to answer right now. Consider the life span of the above-mentioned storage media.

Computer hard drive. Pretty reliable on the one hand device. It works quickly, and it has an unlimited number of rewriting cycles, it all depends on the quality of the magnetic disk. But with a small power surge, an accidental shock (especially when the computer is on), or other surprises, " Winchester' can fail instantly.

Laser CD, "blanks" (blanks, empty " CD" or " DVD”) is the cheapest and fairly reliable option for storing home photo and video collections. They cost no more than 20 rubles in any specialized store. Of course, we also forgot the two-layer " DVD blanks”, which are twice the size of regular CDs. In addition, laser discs have appeared on the market for about two years. blue-ray”, the volume of which is about 25 gigabytes, which is five times larger than the standard “ DVD". But the price of such media is many times higher, and besides, in order to record on a “blue-ray” (translated from English, a blue ray), a special drive is required, the price of which is also far beyond the allowed budget of a simple layman.

And yet, CDs are recommended for quick backups of your favorite files. Only after burning (recording) should they be stored in a dark, dry place where rays of sunlight, the main enemy of laser media, do not pass. It must also be taken into account that guarantee period storage of recorded information on CDs is about six years. At the end of this period, it is better to overwrite the information on another " blank».

What can be said about the reliability of the previously mentioned and well-known flash drive? Despite its small size and ease of use, storage reliability is out of the question. Information can fly off it even at the time of extraction from a computer or other device. These media also break down very often, especially if our Chinese friends took part in its creation.

Solid State Drives "SSD" are also very dubious sources of storage. Of course, their production is much more technologically advanced than the production of "flash drives", but the principle of operation is the same and the disadvantages are the same. Although if you buy such a medium, write down your favorite photos on it and put it in the closet without touching it anymore, it will last a long time. But who can afford such a luxury?

There are quite a few on the web nowadays, quite famous internet resources such as Yandex" and " Google which offer free use of their disk space absolutely free of charge. Such companies are very reliable and in case of failure, information is restored from backups. Typically, such sites, when registering, give you mailbox, and already a bonus is disk space, the size of which starts from 10 gigabytes.

Let's summarize. What media are the best for the user? For a number of the above reasons, the conventional laser disc is becoming the leader. If we also take into account “non-home” storage sources, then, of course, Internet resources will become the undisputed leader, since the percentage of data loss on them is much lower. In general, following the advice of experienced computer scientists, you need to more often duplicate important information on different media, thus reducing the risk of loss to zero.

What did the first man know? How to kill a mammoth, bison or catch a wild boar. In the Paleolithic era, there were enough walls in the cave to record everything studied. The entire cave database would fit on a modest megabyte flash drive. In the 200,000 years of our existence, we have learned about the African frog genome, neural networks, and we no longer draw on rocks. Now we have disks, cloud storage. As well as other types of storage media capable of storing the entire library of Moscow State University on one chipset.

What is a storage medium

A storage medium is a physical object whose properties and characteristics are used to record and store data. Examples of storage media are films, compact optical discs, cards, magnetic disks, paper, and DNA. Storage media differ according to the principle of recording:

• printed or chemical with paint applied: books, magazines, newspapers;
• magnetic: HDD, floppy disks;
• optical: CD, Blu-ray;
• electronic: flash drives, solid state drives.

Data storages are classified according to the waveform:

• analog, using a continuous signal for recording: audio compact cassettes and reels for tape recorders;
• digital - with a discrete signal in the form of a sequence of numbers: floppy disks, flash drives.

The first media

The history of recording and storing data began 40 thousand years ago, when Homo sapiens got the idea to make sketches on the walls of their dwellings. The first rock art is located in the Chauvet cave in the south of modern France. The gallery contains 435 drawings depicting lions, rhinos and other representatives of the Late Paleolithic fauna.

To replace the Aurignacian culture in the Bronze Age, a fundamentally new type of information carrier arose - tuppum. The device was a clay plate and resembled a modern tablet. Recordings were made on the surface using a reed stick - a stylus. To prevent labor from being washed away by rain, tuppums were burned. All tablets with ancient documentation were carefully sorted and stored in special wooden boxes.

The British Museum has a tuppum containing information about a financial transaction that took place in Mesopotamia during the reign of King Assurbanipal. An officer from the prince's retinue confirmed the sale of the slave Arbela. The tablet contains his personal seal and records of the progress of the operation.

Kipu and papyrus

From the III millennium BC, papyrus began to be used in Egypt. Data is recorded on sheets made from the stems of the papyrus plant. The portable and lightweight form of storage media quickly supplanted its clay predecessor. Not only the Egyptians write on papyrus, but also the Greeks, Romans, and Byzantines. In Europe, the material was used until the 12th century. The last document written on papyrus is a papal decree of 1057.

Simultaneously with the ancient Egyptians, at the opposite end of the planet, the Incas invented the kippah, or "talking knots." Information was recorded by tying knots on spinning threads. Kipu kept data on tax collections, population. Presumably, non-numeric information was used, but scientists have yet to unravel it.

Paper and punch cards

From the 12th century to the middle of the 20th century, paper was the main data storage. It was used to create printed and handwritten publications, books, and mass media. In 1808, punched cards began to be made from cardboard - the first digital storage media. They were sheets of cardboard with holes made in a certain sequence. Unlike books and newspapers, punched cards were read by machines, not by people.

The invention belongs to an American engineer with German roots Herman Hollerith. For the first time, the author applied his offspring to compile mortality and birth statistics at the New York Board of Health. After trials, punched cards were used for the 1890 US Census.

But the idea of ​​punching holes in paper to record information was far from new. Back in 1800, Frenchman Joseph-Marie Jacquard introduced punched cards to control a loom. Therefore, the technological breakthrough was the creation by Hollerith not of punched cards, but of a tabulation machine. This was the first step towards automatic reading and calculation of information. Herman Hollerith's TMC tabulating machine company was renamed IBM in 1924.

OMR cards

They are sheets of thick paper with information recorded by a person in the form of optical marks. The scanner recognizes marks and processes the data. OMR cards are used to compile questionnaires, tests with optional choice, bulletins and forms that must be completed manually.

The technology is based on the principle of compiling punched cards. But the machine does not read through holes, but bulges, or optical marks. The calculation error is less than 1%, so government agencies, examining bodies, lotteries and bookmakers continue to use OMR technology.

Perforated tape

A digital storage medium in the form of a long paper strip with holes. Perforated ribbons were first used by Basile Bouchon in 1725 to control a loom and mechanize the selection of threads. But the tapes were very fragile, easily torn and at the same time expensive. Therefore, they were replaced by punched cards.

Since the end of the 19th century, punched tape has been widely used in telegraphy, for entering data into computers of the 1950s-1960s, and as carriers for minicomputers and CNC machines. Now bobbins with wound punched tape have become an anachronism and have sunk into oblivion. Paper media have been replaced by more powerful and voluminous data storages.

Magnetic tape

The debut of magnetic tape as a computer storage medium took place in 1952 for the UNIVAC I machine. But the technology itself appeared much earlier. In 1894, Danish engineer Voldemar Poulsen discovered the principle of magnetic recording while working as a mechanic for the Copenhagen Telegraph Company. In 1898, the scientist embodied the idea in an apparatus called the "telegraph".

A steel wire passed between the two poles of an electromagnet. Recording of information on the carrier was carried out by means of non-uniform magnetization of electric signal oscillations. Voldemar Poulsen patented his invention. At the 1900 World Exhibition in Paris, he had the honor of recording the voice of Emperor Franz Joseph on his device. The exhibit with the first magnetic sound recording is still kept in the Danish Museum of Science and Technology.

When Poulsen's patent expired, Germany began to improve magnetic recording. In 1930 steel wire was replaced by flexible band. The decision to use magnetic stripes belongs to the Austrian-German developer Fritz Pfleimer. The engineer came up with the idea of ​​coating thin paper with iron oxide powder and recording through magnetization. Using magnetic film, compact cassettes, video cassettes and modern storage media for personal computers were created.

HDDs

Winchester, HDD or hard drive is a hardware device with non-volatile memory, which means that information is completely saved, even when the power is turned off. It is a secondary storage device consisting of one or more plates on which data is recorded using a magnetic head. HDDs are located inside the system unit in the drive bay. Connect to motherboard using an ATA, SCSI or SATA cable and to the power supply.

The first hard drive was developed by the American company IBM in 1956. The technology was used as a new type of storage media for the IBM 350 RAMAC commercial computer. The abbreviation stands for "method of random access to accounting and control."

To accommodate the device at home, it would take an entire room. Inside the disc were 50 aluminum plates, 61 cm in diameter and 2.5 cm wide. The size of the storage system was equal to two refrigerators. Its weight was 900 kg. RAMAC capacity was only 5MB. Ridiculous number today. But 60 years ago it was regarded as the technology of tomorrow. After the announcement of the development, the daily newspaper of the city of San Jose released a report titled "Machine with Super Memory!".

Dimensions and capabilities of modern HDDs

A hard drive is a computer storage medium. Used to store data, including images, music, videos, text documents, and any content created or downloaded. It also contains files for operating system and software.

The first hard drives contained up to several tens of MB. Constantly evolving technology allows modern HDDs to store terabytes of information. This is about 400 films with medium extension, 80,000 songs in mp3 format or 70 computer role playing, similar to Skyrim, on one device.

Diskette

The floppy, or floppy disk, is a storage medium created by IBM in 1967 as an alternative to the HDD. Floppy disks were cheaper than hard drives and were intended for storing electronic data. Early computers did not have a CD-ROM or USB. Floppy disks were the only way to install new program or backup.

The capacity of each 3.5-inch floppy was up to 1.44 MB, when one program "weighed" at least one and a half megabytes. That's why Windows version 95 appeared immediately on 13 DMF floppy disks. The 2.88 MB floppy disk appeared only in 1987. This electronic storage medium existed until 2011. Modern computers do not have floppy drives.

Optical media

With the advent of the quantum generator, the popularization of optical storage devices began. Recording is carried out by a laser, and data is read out due to optical radiation. Examples of storage media:

• Blu-ray discs;
• CD-ROM discs;
• DVD-R, DVD+R, DVD-RW and DVD+RW.

The device is a disk covered with a layer of polycarbonate. There are micro-pits on the surface, which are read by the laser during scanning. The first commercial laser disc appeared on the market in 1978, and in 1982 the Japanese company SONY and Philips launched CDs. Their diameter was 12 cm, and the resolution was increased to 16 bits.

Electronic media in the CD format were used exclusively for the reproduction of sound recordings. But at the time, it was cutting-edge technology, for which Royal Philips Electronics received an IEEE award in 2009. And in January 2015, the CD was awarded as the most valuable innovation.

In 1995, digital versatile discs or DVDs appeared, becoming the next generation of optical media. To create them, a different type of technology was used. Instead of red, the DVD laser uses shorter infrared light, which increases the storage capacity. Dual layer DVDs can store up to 8.5 GB of data.

Flash memory

Flash memory is an integrated circuit that does not require constant power to store data. In other words, it is a non-volatile semiconductor computer memory. Memory devices with flash memory are gradually conquering the market, displacing magnetic media.

Advantages of Flash technology:

• compactness and mobility;
• large volume;
• high speed of work;
• low power consumption.

Flash storage devices include:

• USB flash drives. This is the simplest and cheapest storage medium. Used for multiple recording, storage and transmission of data. Sizes range from 2 GB to 1 TB. Contains a memory chip in a plastic or aluminum case with USB connector.
• Memory cards. Designed to store data on phones, tablets, digital cameras and other electronic devices. They differ in size, compatibility and volume.
• SSD. Solid state drive with non-volatile memory. This is an alternative to a standard hard drive. But unlike hard drives, SSDs do not have a moving magnetic head. Due to this, they provide quick access to data, do not emit squeaks, like HDDs. Of the shortcomings - the high price.

Cloud storage

Online cloud storages are modern information carriers, which are a network of powerful servers. All information is stored remotely. Each user can access data at any time and from anywhere in the world. The disadvantage is complete dependence on the Internet. If you don't have a network or Wi-Fi connection, you won't be able to access your data.

Cloud storage is much cheaper than its physical counterparts and has a large volume. The technology is actively used in the corporate and educational environment, development and design of computer software web applications. On the cloud, you can store any files, programs, backups, use them as a development environment.

Of all the listed types of information carriers, the most promising are cloud storage. Also, more and more PC users are moving from magnetic hard drives to solid state drives and flash media. The development of holographic technologies and artificial intelligence promises the emergence of fundamentally new devices that will leave flash drives, SDDs and disks far behind.

The main types of storage media

Information carriers: living beings, inanimate objects and structures, signal, sign, symbol. Any object carries some information about itself and the objects surrounding it, that is, it is a carrier of information.

There is an idea that information carriers have real, material properties and properties of relations. The former imply the properties of the substances from which the carriers are made; the second are the properties of processes and fields, with the help of which carriers exist, and the third are elemental (species) properties that allow one to distinguish one carrier from another, for example, by shape and size. Real media are divided into: local (computer), alienable (portable disks and floppy disks) and distributed (communication lines). With regard to the latter, there is no unequivocal opinion, because communication channels can be represented as data carriers, but at the same time they are the medium for their transmission.

Usually under information carriers imply the generally accepted name of their form, that is: paper (book, brochure, etc.), plate (gramophone record, photographic plate), film (photo, film, x-ray film) audio cassette, floppy disk, microform (photographic film, microfilm, microfiche), video cassette, CD CD , DVD ) etc.

It has long been known, such media as: stone (rock paintings, stone slabs), clay tablets, parchment, papyrus, birch bark and others. Then the following media appeared: paper, plastic, photographic materials, magnetic and optical materials, and more.

Now they are divided into: traditional and machine-readable. Under traditional we will understand the following information carriers: paper, canvas, plastic (gramophone record), magnetic tape (audio and video cassette), photographic materials (photographic film, photographic plate, photographic print, microcarrier), etc. To machine-readable media Let's include: floppy disks (floppy magnetic disks), hard magnetic and compact (optical, magneto-optical and other) disks, flash cards and other storage media intended for use in computer devices, complexes, systems and networks. Information is written to the media by changing the physical, chemical or mechanical properties of the storage medium.

A variant of the classification of information carriers used in computer technology is shown in Fig. 5-1.

Rice. 5-1. Classification of storage media used

in computer technology

Note that this division is conditional. So, for example, with the help of special devices on computers, you can work with ordinary audio and video cassettes, and devices for recording and long-term storage of data (streamers) use well-known magnetic media (magnetic tapes), etc. Therefore, we will refer to traditional media as analog data, and to machine-readable, that is, used in computers, digital data or electronic information resources (EIR).

Let's give them a brief description.

A magneto-optical disk (MO) is enclosed in a plastic envelope (cartridge). MO-disk is a universal, operational, highly reliable device for transferring and storing information. They are characterized by a high density of information recording. Disks with a diameter of 3.5 "have a capacity of 128 MB - 1.3 GB, and with a diameter of 5.25" - from 2.3 to 9.1 GB. Disc rotation speed - 2000 rpm.