Types of electronic storage media. New generation blanks

Electronic storage media

The technology of recording information on magnetic media appeared relatively recently - approximately in the middle of the 20th century (40s - 50s). But several decades later - in the 60s and 70s - this technology became very widespread throughout the world.

Magnetic tape consists of a strip of dense material onto which a layer of ferromagnetic materials is sprayed. It is on this layer that information is “remembered”. The recording process is also similar to the recording process on vinyl records- using a magnetic induction coil instead of special apparatus A current is supplied to the head, which activates the magnet. Sound recording on film occurs due to the action of an electromagnet on the film. The magnetic field of the magnet changes in time with sound vibrations, and thanks to this, small magnetic particles (domains) begin to change their location on the surface of the film in in a certain order, depending on the impact on them magnetic field created by an electromagnet. And when playing back the recording, a process is observed reverse write: the magnetized tape excites electrical signals in the magnetic head, which, after amplification, are sent further to the speaker.

Compact cassette (audio cassette or simply cassette) is an information carrier on magnetic tape; in the second half of the 20th century, it was a common media carrier for sound recording. Used to record digital and audio information. The compact cassette was first introduced in 1964 by Philips. Due to its relative cheapness for a long time(from the early 1970s to the 1990s) the compact cassette was the most popular recorded audio medium, however, starting in the 1990s,

was supplanted by compact discs.

Now there are many in the world various types magnetic media: floppy disks for computers, audio and video cassettes, reel-to-reel tapes, etc. But new laws of physics are gradually being discovered, and with them new possibilities for recording information. Just a couple of decades ago, many storage media based on new technology- reading information using lenses and a laser beam.

The development of material carriers of documented information generally follows the path of a continuous search for objects with high durability, great information capacity with minimal physical dimensions carrier. Since the 1980s, optical (laser) disks have become increasingly widespread. These are plastic or aluminum disks designed to record and reproduce information using a laser beam.

Based on application technology, optical, magneto-optical and digital compact discs are divided into 3 main classes:

1. Discs that allow single recording and repeated playback of signals without the possibility of erasing them (CD-R; CD-WORM - Write-Once, Read-Many - recorded once, counted many times). Used in electronic archives and data banks, in external drives COMPUTER.

2. Reversible optical discs, allowing you to repeatedly record, play and erase signals (CD-RW, CD-E). This is the most universal wheels, capable of replacing magnetic media in almost all areas of application.

3. Digital universal video discs DVD (Digital Versatile Disk) such as DVD-ROM, DVD-RAM, DVD-R with large capacity(up to 17 GB).

Name optical disks determined by the method of recording and reading information. The information on the track is created by a powerful laser beam that burns depressions on the mirror surface of the disk, and is an alternation of depressions and reflective areas. When reading information, the mirror islands reflect the light of the laser beam and are perceived as one (1), the depressions do not reflect the beam and, accordingly, are perceived as zero (0). This principle allows you to achieve high density recording information, and therefore large capacity with minimal dimensions. CD is the ideal remedy storage of information is ridiculously cheap, practically not subject to any environmental influences, information recorded on it will not be distorted or erased until the disk is physically destroyed, and has a capacity of 700 MB.

Magneto-optical disk is an information carrier that combines the properties of optical and magnetic storage devices. The disk is made using ferromagnets. Magneto-optical disks, for all their advantages, have serious drawbacks: relatively low write speed, caused by the need to erase the contents of the disk before writing, and after writing - a read test; high energy consumption - to heat the surface, lasers of significant power are required, and therefore high energy consumption. This makes it difficult to use MO burner drives in mobile devices.

DVD (Digital Versatile Disc - digital multi-purpose disk) is a disk-shaped information carrier that is similar in appearance to a CD, but has the ability to store a larger amount of information due to the use of a laser with a shorter wavelength, than for regular CDs. The first discs and DVD players appeared in November 1996 in Japan and March 1997 in the USA. They were intended for recording and storing video images. It’s interesting that the first 3.95 GB DVD discs cost $50 apiece back then. Currently, there are six varieties of such disks with capacities from 4.7 to 17.1 GB. They are used to record and store any information: video, audio, data.

Working with information in our time is unthinkable without a computer, since it was originally created as a means of information processing and only now it began to perform many other functions: storage, transformation, creation and exchange of information. But before it took on its now familiar form, the computer underwent three revolutions.

The first computer revolution has come to an end

50s; its essence can be described in two words: computers appeared.

They were invented no less than ten years earlier, but it was at that time that serial machines began to be produced; these machines ceased to be an object of research for scientists and a curiosity for everyone else. A decade and a half later, no large organization could afford to do without a computer center. If you talked about a computer back then, you immediately imagined computer rooms filled with racks, in which people in white coats were thinking intently. And then the second revolution took place. Almost simultaneously, several companies discovered that the development of technology had reached a level where it was not necessary to build a computer center around the computer, and the computer itself had become small. These were the first minicomputers. But another ten years passed, and the third revolution came - in the late 70s, personal computers. In a short time, having gone from a desktop calculator to a full-fledged small machine, PCs took their place on the desktops of individual users.

At the very moment when the first computer processed a few bytes of data for the first time, the question immediately arose: where and how to store the results obtained? How to save calculation results, text and graphic images, arbitrary data sets?

First of all, there must be a device with which the computer will store information, then a storage medium is required on which it can be transferred from place to place, and another computer must also easily read this information. Let's take a look at some of these devices.

1. Punched card reader: designed for storing programs and data sets using punched cards - cardboard cards with punched holes a certain sequence holes. Punch cards were invented long before the advent of the computer; with their help, very complex and beautiful fabrics were produced on looms, because they controlled the operation of the mechanism. Change the set of punched cards and the fabric pattern will be completely different - it depends on the location of the holes on the card. In relation to computers, the same principle was used, only instead of a pattern of fabric, holes were given commands to the computer or sets of data. This method of storing information is not without its disadvantages: - very low speed access to information; - a large volume of punched cards for storing a small amount of information; - low reliability of information storage; - in addition, small circles of cardboard were constantly flying from the puncher, which fell on their hands, in their pockets, got stuck in their hair, and the cleaning ladies were terribly unhappy. People were forced to use punch cards not because they particularly liked this method, or because it had some undeniable advantages, no, it had no advantages at all, it’s just that at that time there was nothing else, there was nothing to choose from , I had to get out.

2. Magnetic tape drive (streamer): based on the use of a tape-type device and cassettes with magnetic film. This method of storing information has been known for a long time and is successfully used today. This is explained by the fact that a fairly large amount of information can be placed on a small cassette; the information can be stored for a long time and its access speed is much higher than that of a punch card reader. On the other hand, the streamer is only suitable for accumulating, storing large amounts of information, and backing up data. It is almost impossible to process information using a streamer: a streamer is a device sequential access to the data: to get the 5th file we must scroll through four. What if you need a 7529?

3. Floppy magnetic disk drive (FMD - disk drive). This device uses flexible magnetic disks as a storage medium - floppy disks, which can be 5 or 3 inches. A floppy disk is a magnetic disk, like a record, placed in a cardboard envelope. Depending on the size of the floppy disk, its capacity in bytes varies. If a standard 5"25" floppy disk can hold up to 720 KB of information, then a 3"5" floppy disk can hold 1.44 MB. Floppy disks are universal, suitable for any computer of the same class equipped with a disk drive, and can be used for storing, accumulating, distributing and processing information. The drive is a parallel access device, so all files are equally easily accessible. Disadvantages include small capacity, which makes long-term storage almost impossible large volumes information, and not very high reliability of the floppy disks themselves.

4. Hard magnetic disk drive (HDD - hard drive): is a logical continuation of the development of magnetic information storage technology. They have very important advantages: - extremely large capacity; - simplicity and reliability of use; - the ability to access thousands of files simultaneously; - high speed access to data.

5. CDs and DVDs we have already reviewed.

But since the flow of information is only increasing, it is necessary to develop more and more new means and devices for its creation, processing, storage and transmission.

We have already discussed above storing data on CDs and DVDs. Despite their convenience, due to the need to use the largest possible amount of information, the process of replacing them is already beginning. In the coming years, such personal devices computer technology Like a computer, flash memory will be a formidable rival to hard drives.

6. Flash memory is a type of solid-state semiconductor non-volatile rewritable memory.

Due to its compactness, low cost and low power requirements, flash memory is already widely used in portable devices operating on batteries and accumulators - digital cameras and video cameras, digital voice recorders, MP3 players, PDAs, mobile phones, as well as smartphones. In addition, it is used to store built-in software in various peripheral devices(routers, PBXs, communicators, printers, scanners). It does not contain moving parts, so, unlike hard drives, it is more reliable and compact.

Basics weak point flash memory -- the number of rewrite cycles. It can be read as many times as desired, but it can only be written to such memory a limited number of times (usually about 10 thousand times). Despite the fact that there is such a limitation, 10 thousand rewrite cycles is much more than a floppy disk or CD can withstand. Flash memory is best known for its use in USB flash drives. USB flash drive). Thanks to high speed, volume and compact USB sizes Flash media is already pushing CDs out of the market.

Plan

Introduction………………………………………………………………………………………...3

Storage media……………………………………………………………4

Encoding and reading information..……………………………………9

Development prospects…………………….…………………………………….15

Conclusion………………………………………………………………………………….18

Literature…………………………………………………………………………………19

Introduction

In 1945, John von Neumann (1903-1957), an American scientist, came up with the idea of ​​using external storage devices to store programs and data. Neumann developed a block diagram of a computer. All modern computers follow Neumann's scheme.

External memory is designed for long-term storage of programs and data. External memory devices (drives) are non-volatile; turning off the power does not lead to data loss. They can be built into system unit or made in the form of independent blocks connected to the system through its ports. Based on the method of recording and reading, drives are divided, depending on the type of media, into magnetic, optical and magneto-optical.

Information coding is the process of forming a specific representation of information. A computer can only process information presented in numerical form. All other information (for example, sounds, images, instrument readings, etc.) must be converted into numerical form for processing on a computer. As a rule, all numbers in a computer are represented using zeros and ones (not ten digits, as is usual for people). In other words, computers usually operate in the binary number system, since this makes the devices for processing them much simpler.

Reading information– retrieving information stored in a storage device (memory) and transferring it to other devices of the computer. Reading information is performed when performing most machine operations, and sometimes is an independent operation.

During the abstract, we will consider the main types of information carriers, encoding and reading information, as well as development prospects.

Storage media

Historically, the first storage media were punched tape and punched card input/output devices. Following them came external recording devices in the form of magnetic tapes, removable and permanent magnetic disks and magnetic drums.

Magnetic tapes are stored and used wound on reels. There were two types of coils: feeding and receiving. Tapes are supplied to users on feed reels and do not require additional rewinding when installing them in drives. The tape is wound onto a reel with the working layer inward. Magnetic tapes are classified as indirect access storage devices. This means that the search time for any record depends on its location on the media, since the physical record does not have its own address and in order to view it you need to view the previous ones. Direct access storage devices include magnetic disks and magnetic drums. Their main feature is that the search time for any record does not depend on its location on the media. Each physical record on the medium has an address that allows direct access to it, bypassing other records. The next type of recording devices were packages of removable magnetic disks, consisting of six aluminum disks. The capacity of the entire package was 7.25 MB.

Let's take a closer look at modern storage media.

1. Floppy magnetic disk drive (FMD – disk drive).

This device uses flexible magnetic disks as a storage medium - floppy disks, which can be 5 or 3 inches. A floppy disk is a magnetic disk, like a record, placed in an “envelope.” Depending on the size of the floppy disk, its capacity in bytes varies. If a standard 5'25" floppy disk can hold up to 720 KB of information, then a 3'5" floppy disk can hold 1.44 MB. Floppy disks are universal, suitable for any computer of the same class equipped with a disk drive, and can be used for storing, accumulating, distributing and processing information. The drive is a parallel access device, so all files are equally easily accessible. The disk is covered on top with a special magnetic layer, which ensures data storage. Information is recorded on both sides of the disk along tracks that are concentric circles. Each track is divided into sectors. The data recording density depends on the density of tracks on the surface, i.e., the number of tracks on the surface of the disk, as well as on the density of information recording along the track. The disadvantages include small capacity, which makes long-term storage of large amounts of information almost impossible, and the not very high reliability of the floppy disks themselves. Currently, floppy disks are practically not used.

2. Hard magnetic disk drive (HDD - hard drive)

It is a logical continuation of the development of magnetic information storage technology. Main advantages:

– large capacity;

– simplicity and reliability of use;

– the ability to access multiple files simultaneously;

– high speed of data access.

Among the shortcomings we can only highlight the lack removable media information, although external hard drives and backup systems are currently used.

The computer provides the ability, using a special system program, to conditionally split one disk into several. Such disks, which do not exist as a separate physical device, but represent only part of one physical disk, are called logical disks. Logical drives are assigned names using Latin letters [C:], , [E:], etc.

3. Compact disc reader (CD-ROM)

These devices use the principle of reading grooves on a metallized carrier layer of a compact disc with a focused laser beam. This principle makes it possible to achieve a high density of information recording, and, consequently, a large capacity with minimal dimensions. A CD is an excellent means of storing information, it is cheap, practically not subject to any environmental influences, the information recorded on it will not be distorted or erased until the disk is physically destroyed, its capacity is 650 MB. It has only one drawback - a relatively small amount of information storage.

A) Differences between DVD and regular CD-ROM

The most basic difference is, naturally, the amount of information recorded. If you can burn 650 MB on a regular CD (although lately There are blanks with 800 MB, but not all drives will be able to read what is written on such a medium), then one DVD disc will fit from 4.7 to 17 GB. DVD uses a laser with a shorter wavelength, which has significantly increased the recording density, and in addition, DVD implies the possibility of two-layer information recording, that is, on the surface of the compact there is one layer, on top of which another, translucent one is applied, and the first is read through the second in parallel . There are also more differences in the media themselves than seems at first glance. Due to the fact that the recording density has increased significantly and the wavelength has become shorter, the requirements for the protective layer have also changed - for DVD it is 0.6 mm versus 1.2 mm for regular CDs. Naturally, a disk of such thickness will be much more fragile compared to a classic blank. Therefore, another 0.6 mm is usually filled with plastic on both sides to get the same 1.2 mm. But the main bonus of such a protective layer is that, thanks to its small size, it became possible to record information on both sides on one compact, that is, to double its capacity, while leaving the dimensions almost the same.

B) DVD capacity

There are five types of DVDs:

1. DVD5 – single-layer, single-sided disc, 4.7 GB, or two hours of video;

2. DVD9 – double-layer single-sided disc, 8.5 GB, or four hours of video;

3. DVD10 – single-layer double-sided disc, 9.4 GB, or 4.5 hours of video;

4. DVD14 – double-sided disc, two layers on one side and one on the other side, 13.24 GB, or 6.5 hours of video;

5. DVD18 – double-layer, double-sided disc, 17 GB, or more than eight hours of video.

The most popular standards are DVD5 and DVD9.

IN) Possibilities

The situation with DVD media now resembles that of CDs, which for a long time also only stored music. Now you can find not only films, but also music (so-called DVD-Audio) and software collections, games, and films. Naturally, the main area of ​​use is film production.

G) Sound in DVD

Audio can be encoded in many formats. The most famous and frequently used are Dolby Prologic, DTS and Dolby Digital of all versions. That is, in fact, in the formats used in cinemas to obtain the most accurate and colorful sound picture.

D) Mechanical damage

TO mechanical damage CDs and DVDs are equally sensitive. That is, a scratch is a scratch. However, due to the much higher recording density, the losses on the DVD disc will be more significant. Now there are programs that can recover information even from damaged disks, though with the skipping of damaged sectors.

5. Portable USB drives

Fast-growing portable market hard drives, designed for transporting large amounts of data, attracted the attention of one of the largest hard drive manufacturers. Western Digital has announced the release of two device models called WD Passport Portable Drive. Options with a capacity of 40 and 80 GB are on sale. WD Passport Portable Drives are based on 2.5-inch WD Scorpio EIDE HDDs. They are packaged in a rugged case, equipped with support for Data Lifeguard technology, and do not require an additional power source (powered via USB). The manufacturer notes that the drives do not heat up, operate quietly and consume little energy.

6.USB Flash Drive

A new type of external storage medium for a computer, which appeared due to the widespread use of the USB (universal bus) interface and the advantages of Flash memory chips. A sufficiently large capacity with a small size, energy independence, high speed of information transfer, protection from mechanical and electromagnetic influences, the ability to be used on any computer - all this allowed the USB Flash Drive to replace or successfully compete with all previously existing storage media.

, plastic with special properties (for example, in optical discs) and others.

An information carrier can be any object from which it is possible (accessible) to read (read) the information available on it (printed, recorded).

Information carriers in science (libraries), technology (say, for communication needs), public life (media), and everyday life are used for:

• records;
• storage;
• reading;
• transmission (distribution);
• creating works of computer art.

Often, the information carrier itself is placed in a protective shell, which increases its safety and, accordingly, the reliability of storing information (for example: paper sheets are placed in a cover, a memory chip is placed in plastic (smart card), magnetic tape is placed in a case, etc. ).

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Subtitles

The hard drive is an external storage medium and, from my point of view, it has the most important function for the user. The point is that it contains operating system, application programs and user files, that is, everything that allows you to use the computer for its intended purpose. Understanding the essence of how a hard drive works will allow you to competently configure information storage areas, as well as independently diagnose problems that are quite often associated with this particular device. Name " hard drive» ( Hard Disk Drive) has been attached to this device for a long time and it is connected with the fact that the predecessor of the hard drive were floppy disks, which were called floppy disks. Nobody uses floppy disks anymore, but the name “hard drive” remains the same. Now I will not go into detail about the device hard drive, since I have a whole small video course dedicated to this issue. Let me just say that the hard drive is the only mechanical device in a computer, and it is this fact that imposes a number of limitations. The most basic limitation is the speed of reading and writing data. Windows 7 has something called performance index, which evaluates various computer subsystems in points and shows the degree of their influence on overall performance. By the way, the Windows Performance Index did not live up to the expectations of the operating system developers and is quite difficult to navigate when choosing software, and this is precisely the task that was originally assigned to it. Starting with Windows 8.1, developers removed the performance index, or rather, it is missing from graphical interface, although you can still test using commands. I'll talk about this in more detail a little later. So, the hard drive, as the weakest link, has the maximum impact on the overall performance assessment. As I already said, the reason is quite simple - the electro-mechanical design of a hard drive is capable of providing data read-write speeds only at a limited level. The read-write speed directly depends on the rotation speed of the magnetic drum and, as you understand, this speed is limited. Usually it is 7200 rpm, but there are discs with rotation speeds of both 10,000 and 15,000 rpm. Such hard drives much more expensive and their use in home computers is impractical. Ten years ago, the data transfer speed provided by hard drives was quite sufficient, but now the performance of other computer systems has increased significantly and the hard drive has become the weakest link. So, despite a number of obvious shortcomings, the hard drive is still the most common storage medium today. However, it has long had a competitor - a solid-state drive (SSD - solid-state drive), which, roughly speaking, is a large flash drive. An SSD does not have the disadvantages of a hard drive, for example, it is absolutely silent, since it does not contain mechanical parts, and, of course, it provides data transfer speeds several times higher than the speed of hard drives. But still, I believe that the hard drive will remain in the lead for quite some time due to optimal ratio its cost and the volume of stored information. Solid-state drives are still quite expensive and not everyone can afford them, although you can significantly improve the performance of your computer quite inexpensively, and we will definitely talk about this later. The most important thing that you need to understand now is that the operation of the operating system and programs installed on the computer does not depend in any way on the principles of operation of the storage medium. That is, it doesn’t matter whether you use a hard drive or an SSD. If you are interested in the design of a hard drive, then pay attention to my video course “Hard Drives: Problems and Solutions.” In it I analyzed in detail and hard device disk, and the problems that are most typical for these storage media. However, I would recommend studying this course after completing this... Well, now I would like to focus not on the physical structure of the storage media, but on the software component, that is, on how the operating system perceives the storage media. This point is very important, since it is directly related to the installation of the operating system on the computer, and also concerns the organization of storing user information on the computer. And about him we'll talk in the next video.

Media classification

• for one-time recording;
• For multiple write.

• for long-term storage (cessation of the carrier function is due to random circumstances);
• for short-term storage (cessation of function is due to natural processes leading to inevitable degradation of the medium).

Basic materials

To make changes to the structure of the carrier material, various types impacts:

• mechanical (carving, drilling, sewing);
• thermal (burning, baking [ ]);
• electrical (electrical signals);
• chemical (painting, etching, etc.);

Electronic media

TO electronic media include write-once or write-once media (usually digital) electrically:

• optical (CD-ROM, DVD-ROM, Blu-ray Disc);
• semiconductor (flash memory, floppy disks, etc.).

Electronic media have significant advantages over paper media (sheets, newspapers, magazines):

• by volume (size) of stored information;
• by unit cost of storage;
• on the efficiency and efficiency of providing up-to-date (intended for short-term storage) information;
• whenever possible, providing information in a form convenient for the consumer (formatting, sorting).

Storage devices

Storage device consists of the following elements:

• information carrier;
• recording device- mechanisms that record information on the medium;
• reader (reader) - mechanisms that read information from the media.

Information storage- an information storage device capable of adding incoming information to existing information.

These devices can be based on a variety of physical principles.

If the storage medium is not widely used, it must be protected from external influences, or requires complex settings, then it can be delivered to the consumer complete with a reading/writing device (for example, a music box, a command device (electromechanical programmer) of a washing machine).

Story

The need to exchange information, preserve written evidence about one’s life, etc. has always existed for humans. Throughout the history of mankind, many information carriers have been tried. Since the medium has a number of parameters, the evolution of the information medium was determined by what requirements were placed on it.

Ancient times

Disadvantage of this medium The problem was that over time it darkened and broke. An additional disadvantage was that the Egyptians introduced a ban on the export of papyrus abroad.

Asia

The disadvantages of storage media (clay, papyrus, wax) stimulated the search for new media. This time the principle “everything new is well forgotten old” worked: c). Books on parchment - palimpsests(from Greek παλίμψηστον - a manuscript written on parchment using washed or scraped text).

As in other countries, Southeast Asia has tried many different ways recording and saving information:

Due to the shortcomings of the previous carriers, the Chinese emperor Liu Zhao ordered a worthy replacement to be found, and one of the officials (Tsai Lun) in 105 AD. e. developed a method for producing paper (which has not changed much to this day) from wood fibers, straw, grass, moss, rags, tow, plant waste, etc. Some historians claim that Tsai Lun learned the process of making paper from the paper wasp ( builds a nest from wood fibers chewed and moistened with sticky saliva) τετράς translated from Greek - four).

However, inscriptions on wax are short-lived, and the problem of preserving records was very pressing.

Storage media – material that is intended for recording, storage and subsequent reproduction of information.

Storage medium - a strictly defined part of a specific information system, used for intermediate storage or transmission of information.

Storage medium - This physical environment, in which it is fixed.

The media can be paper, photographic film, brain cells, punched cards, punched tapes, magnetic tapes and disks or computer memory cells. Modern technology offers more and more new types of storage media. To encode information, they use electrical, magnetic and optical properties materials. Media are being developed in which information is recorded even at the level of individual molecules.

IN modern society There are three main types of storage media:

1) Perforated - have a paper base, information is entered in the form of punches in the corresponding row and column. The volume of information is 800 bits or 100 KB;

2) Magnetic – they use flexible magnetic disks and cassette magnetic tapes;

3) optical.

Information carriers include:

Magnetic disks;

- magnetic drums- early variety computer memory, widely used in 1950-1960. Invented by Gustav Tauschek in 1932 in Austria. Later, the magnetic drum was replaced by memory on magnetic cores.

- floppy disks- portable magnetic medium information used for repeated recording and storage of relatively small data. Writing and reading is done using special device- disk drive;

- magnetic tapes- a magnetic recording medium, which is a thin flexible tape consisting of a base and a magnetic working layer;

- optical discs- an information carrier in the form of a disk with a hole in the center, information from which is read using a laser. The compact disc was originally created for digital audio storage, but is now widely used as a general-purpose storage device;

- flash memory - a type of solid-state semiconductor non-volatile rewritable memory. Flash memory can be read as many times as you like, but it can only be written to a limited number of times (usually about 10 thousand times). Erasing occurs in sections, so you cannot change one bit or byte without overwriting the entire section.

All media can be divided into:

1. Human readable (documents).

2. Machine-readable (machine) - for intermediate storage of information (disks).

3. Human-machine-readable – combined media for highly specialized purposes (forms with magnetic stripes).

However, the rapid development of computer technology has erased the line between the 1st and 3rd groups - a scanner has appeared that allows you to enter information from documents into the computer memory.

All currently available storage media can be divided according to various criteria. First of all, it is necessary to distinguish volatile And non-volatile information storage devices.

Non-volatile drives used for archiving and saving data arrays are divided into:

1. by type of record:

– magnetic storage devices (hard disk, floppy disk, removable disk);

– magnetic-optical systems, also called MO;

– optical, such as CD (Compact Disk, Read Only Memory) or DVD (Digital Versatile Disk);

2. by construction methods:

– a rotating plate or disk (like a hard drive, floppy disk, removable disk, CD, DVD or MO);

– tape media various formats;

– drives without moving parts (for example, Flash Card, RAM (Random Access Memory), which have a limited scope due to the relatively small volumes memory compared to the above).

If required quick access to information, such as when outputting or transmitting data, then media with a rotating disk are used. For archiving performed periodically (Backup), on the contrary, tape media are more preferable. They have large amounts of memory combined with a low price, although at relatively low performance.

Based on their purpose, storage media are divided into three groups:

1. dissemination of information: Pre-recorded media such as CD ROM or DVD-ROM;

2. archiving: media for one-time recording of information, such as CD-R or DVD-R (R (record able) - for recording);

3. backup or data transfer: media with the ability to record information reusably, such as floppy disks, hard disks, MO, CD-RW (RW (rewritable) - rewritable and tapes.

Storage medium– physical environment that directly stores information. The main carrier of information for a person is his own biological memory (the human brain). A person's own memory can be called RAM. Here the word “operative” is synonymous with the word “fast”. Memorized knowledge is reproduced by a person instantly. We can also call our own memory internal memory, since its carrier - the brain - is located inside us.

Storage medium- a strictly defined part of a specific information system that serves for intermediate storage or transmission of information.

The basis of modern information technology- This is a computer. When we're talking about about computers, then we can talk about storage media as external storage devices (external memory). These storage media can be classified according to various criteria, for example, by type of execution, material from which the media is made, etc. Here is one option for classifying storage 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 operating properties of magnetic tape are characterized by its sensitivity during recording and signal distortion during recording and playback. The most widely used is 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 storage media refer to direct access machine media. 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 most diverse:

Floppy magnetic disk drives (FMD), also known as floppy disks, also known as floppy disks

Drives on hard magnetic disks (HDD), they are also hard drives (popularly just “screws”)

Optical CD drives:

• CD-ROM (Compact Disk ROM)

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

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

The information capacity of the floppy disk is small and is 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-removable disk magnetic storage devices. The first hard drive was developed by IBM in 1973 and had a capacity of 16 KB. Hard magnetic disks are several dozen disks placed on one axis, enclosed in a metal case and rotating at high angular speed. The speed of writing and reading information from hard drives is quite high (about 133 MB/s) due to the fast rotation of the disks (7200 rpm).

During the operation of the computer, malfunctions occur. Viruses, power outages, software errors - all this can cause damage to information stored on your hard drive. Damage to information does not always mean its loss, 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, having restored the damaged area, continue normal work with the preservation of all your invaluable data.

Hard drives use fairly fragile and miniature elements. To preserve information and the 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 - This laser discs and players.

Laser disk drives use the optical principle of reading information. On laser discs CD (CD - Compact Disk, compact disc) and DVD (DVD - Digital Video Disk, digital video disc), information is recorded on one spiral-shaped track (like on a gramophone record), containing alternating sections with different reflectivity. A 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 acquires values ​​0 or 1. To preserve information, laser disks must be protected from mechanical damage (scratches), as well as from contamination. Laser discs store information that was recorded on them during the manufacturing process. It is impossible to write new information to them. Such discs are produced by stamping. There are CD-R and DVD-R discs information on which can only be written once. On CD-RW and DVD-RW discs, information can be written/rewritten many times. Discs different types can be distinguished not only by markings, but also by the color of the reflective surface.

Devices based on flash memory.

Flash memory is a non-volatile type of memory that allows data to be written and stored on chips. Devices based on flash memory do not have moving parts, which ensures high data security when used in mobile devices.

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