Classification of long-term information storage devices

The most common are magnetic disk drives, which are divided into hard disk drives (HDDs), floppy disk drives (FMDs), and optical disk drives, such as CD-ROM, CD-R, CD-RW and DVD-ROM.

Detailed characteristics of long-term information storage devices

· Hard magnetic disk drives (HDD)

HDD is the main device for long-term storage of large amounts of data and programs. Other names: hard drive, hard drive, HDD (Hard Disk Drive). Externally, the hard drive is a flat, hermetically sealed box, inside of which there are several round rigid aluminum or glass plates on a common axis. The surface of any disk is covered with a thin ferromagnetic layer (a substance that reacts to an external magnetic field), and the recorded data is actually stored on it. In this case, recording is carried out on both surfaces of each plate (except for the outer ones) using a block of special magnetic heads. Each head is located above the working surface of the disk at a distance of 0.5-0.13 microns. The disk pack rotates continuously and at high speed (4500-10000 rpm), so mechanical contact of heads and disks is unacceptable.

There are a huge number of different models of hard drives from many companies, such as Seagate, Maxtor, Quantum, etc. To ensure compatibility of hard drives, standards have been developed for their characteristics, which determine the range of connecting conductors, their placement in adapter connectors, and the electrical parameters of signals. The most common interface standards are IDE (Integrated Drive Electronics) or ATA and the more productive EIDE (Enhanced IDE) and SCSI (Small Computer System Interface). The characteristics of the interfaces through which hard drives are connected to the motherboard largely determine the performance of modern hard drives.

Among other parameters that affect HDD performance, the following should be noted:

• § disk circulation speed - nowadays EIDE drives are produced with a circulation frequency of 4500-7200 rpm, and SCSI drives - 7500-10000 rpm;
• § cache memory capacity - all modern disk drives have a cache buffer installed, which speeds up data exchange; the greater its capacity, the higher the likelihood that the cache memory will contain the necessary information that does not need to be read from the disk (this process is thousands of times slower); The cache buffer capacity in different devices can vary from 64 KB to 2 MB;
• § average access time - the time (in milliseconds) during which the head block moves from one cylinder to another. Depends on the design of the head drive and is approximately 10-13 milliseconds;
• § delay time is the time from the moment the head block is positioned on the desired cylinder to the positioning of a specific head on a specific sector, in other words, this is the time to search for the desired sector;
• § exchange rate - determines the amount of data that can be transferred from the drive to the microprocessor and in the opposite direction over certain periods of time; the maximum value of this parameter is equal to the disk interface throughput and depends on which mode is used: PIO or DMA; in PIO mode, data exchange between the disk and the controller occurs with the direct participation of the central processor; the higher the PIO mode number, the higher the exchange speed; working in DMA (Direct Memory Access) mode allows you to transfer data directly to RAM without the participation of the processor; Data transfer speeds in modern hard drives range from 30-60 MB/s.
• · Floppy magnetic disk drives (FMD)

The floppy disk drive or disk drive is built into the system unit. Flexible media for floppy disk drives are produced in the form of floppy disks (another name for floppy disks). Actually, the carrier is a flat disk with a special, fairly dense film, coated with a ferromagnetic layer and placed in a protective envelope with a movable latch at the top. Floppy disks are used mainly for quickly transferring small amounts of information from one computer to another. Data recorded on a floppy disk can be protected from being erased or overwritten. To do this, you need to move the small protective slide at the bottom of the floppy disk so that an open window is formed. To enable recording, this slider should be moved back and the window closed.

The main parameters of a floppy disk are the technological size (in inches), recording density and total capacity. By size, there are 3.5-inch floppy disks and 5.25-inch floppy disks (no longer used). The recording density can be simple SD (Single Density), double DD (Double Density) and high HD (High Density). The standard capacity of a 3.5-inch floppy disk is 1.44 MB; floppy disks with a capacity of 720 KB can be used. The current standard is 3.5-inch, high-density HD floppy disks with a capacity of 1.44 MB.

CD-ROM drive

Since 1995, the basic configuration of a personal computer began to include a CD-ROM drive instead of 5.25-inch drives. The abbreviation CD-ROM (Compact Disk Read Only Memory) is translated as a read-only storage device based on compact discs. The operating principle of this device is to read digital data using a laser beam that is reflected from the surface of the disk. A regular CD is used as a storage medium. Digital recording on a CD differs from recording on magnetic disks in its high density, so a standard CD has a capacity of about 650-700 MB. Such large volumes are typical for multimedia information (graphics, music, video), so CD-ROM drives are classified as multimedia hardware. In addition to multimedia publications (electronic books, encyclopedias, music albums, videos, computer games), a variety of large-scale system and application software (operating systems, office packages, programming systems, etc.) are distributed on CDs.

CDs are made of transparent plastic with a diameter of 120 mm and a thickness of 1.2 mm. A layer of aluminum or gold is sprayed onto the plastic surface. In mass production conditions, information is recorded on a disk by extruding tracks on the surface in the form of a series of indentations. This approach provides binary recording of information. Recess (pit - pit), surface (land - land). Logical zero can be represented by either a pit or a land. A logical one is encoded by the transition between pit and land. From the center to the edge of the CD there is a single track in the form of a spiral 4 microns wide with a pitch of 1.4 microns. The surface of the disk is divided into three areas. Lead-In is located in the center of the disk and is read first. It records the contents of the disk, a table of addresses of all records, the disk label and other service information. The middle area contains basic information and takes up most of the disk. The Lead-Out area contains the end-of-disk mark.

For stamping, there is a special prototype matrix (master disk) of the future disk, which extrudes tracks on the surface. After stamping, a protective film of transparent varnish is applied to the surface of the disc.

Main characteristics of CD-ROM:

• § data transfer rate - measured in multiples of the speed of an audio CD player (150 KB/sec) and characterizes the maximum speed at which the drive transfers data to the computer’s RAM, for example, a 2-speed CD-ROM (2x CD-ROM) will read data at a speed of 300 KB/sec, 50-speed (50x) - 7500 KB/sec;
• § access time - the time required to search for information on the disk, measured in milliseconds.

The main disadvantage of standard CD-ROMs is the inability to write data, but there are CD-R write-once and CD-RW write-once devices.

CD-R drive (CD-RECORDABLE)

Externally similar to CD-ROM drives and compatible with them in disc size and recording formats. Allows one-time recording and an unlimited number of readings. Data recording is carried out using special software. The recording speed of modern CD-R drives is 4x-8x.

CD-RW drive (CD-REWRITABLE)

They are used for reusable recording of data, and you can either simply add new information to free space or completely overwrite the disk with new information (previous data is destroyed). As with CD-R drives, to record data you need to install special programs on the system, and the recording format is compatible with a regular CD-ROM. The recording speed of modern CD-RW drives is 2x-4x.

DVD drive (DIGITAL VIDEO DISK)

A device for reading digital video recordings. Externally, a DVD disc is similar to a regular CD-ROM (diameter - 120 mm, thickness 1.2 mm), but differs from it in that up to 4.7 GB can be recorded on one side of the DVD disc, and up to 9.4 GB. If a two-layer recording scheme is used, up to 8.5 GB of information can be placed on one side, respectively, on two sides - about 17 GB. DVDs can be rewritten.

· Outlook DVD

The presence of different standards and specifications does not mean that DVD technology stands still. The efforts of various companies today are aimed at introducing “blue laser” technology - with a shorter wavelength. This will increase the recording density on disks with the resulting improvement in other characteristics.

Calimetrics Inc has proposed ML (multilevel) technology, which can triple the capacity of a standard DVD/CD. In this case, there is no need to make any modifications to the mechanism and optics of existing drives. To implement new technology, it is enough to use a chipset developed by this company. The essence of the technology is the ability to use pit depth (up to 8 levels) as an information characteristic when working with disks. Note that a similar technology, but for CD discs, is being developed by TDK in collaboration with other companies.

• Read-only DVD formats
• Ш DVD-ROM (Digital Versatile Disc Read Only Memory)

DVD-ROM discs are intended for use in computer technology. Information is written to the disk only once - during its production.

The progress of DVD devices largely follows the path traversed by CDs, and is aimed mainly at improving speed characteristics and introducing a recording function. First-generation DVD-ROM devices used CLV mode and read from the disc at a speed of 1.38 MB/s (in traditional DVD notation this is 1x). Second-generation devices could read DVDs at twice the speed - 2x (2.8 MB/s). Modern DVD-ROMs - third-generation devices - use rotation control mode (CAV) with a maximum reading speed of 4x-6x (5.5 - 8.3 MB/s) or more. Modern DVD-ROM drives (disk drives) support reading almost all formats, including CDs.

The DVD-Video format is designed for storing and playing video. Like DVD-ROM, this specification defines the ability to read-only information - playback of recordings using video players (video recorders). The specification is based on the DVD-ROM format, but provides a special way of placing data that prevents the possibility of bit-by-bit copying of discs. Video materials in encoded form are placed on the disk during the production process. Playing DVD-video is only possible on household video players (video recorders) or DVD drives connected to a computer. When using computer equipment, information decoding is carried out either in hardware or software. The modern specification ensures recording of high-quality video on disc (up to 2 hours in MPEG-2 compression format). And also multi-channel audio in 8 languages, choice of screen format, captions in 32 languages, interactive control via on-screen menu, up to 9 angular viewing directions, protection against illegal copying, delimitation of viewing video products by region, control of children’s access to video materials.

A new generation of music format after CD. The format specification defines high-quality multi-channel sound, support for a wide range of sound quality (quantization 16, 20, 24 bits at a frequency of 44.1 to 192 kHz), playback of CD players by DVD players, support for additional information (including video, text, menus, screensavers, convenient navigation system), connection with websites providing information support, expansion of capabilities with the emergence of new technologies.

There are two versions of the DVD-Audio format: simply DVD-Audio - for audio content only, and DVD-AudioV - for audio with additional information.

Special measures have been developed to protect disks from pirated copying.

• · DVD formats for multiple recording
• Ш Multiple write

All known specifications of rewritable DVD discs use multiple recording technology based on the physical principle of changing the phase state (crystalline/amorphous) of the information layer under the influence of a laser with a wavelength of 650 (635) nm (phase-change recording). Reading information is carried out by determining the optical characteristics of the information layer in its various phase states upon reflection of laser beams (the same as during recording).

Ш DVD-RAM (Digital Versatile Disc Random Access Memory)

Rewritable format developed by Panasonic, Hitachi, Toshiba.

The format was approved by the DVD forum in July 1997. Equipment and discs of this format were tested for 3 months in more than 20 computer manufacturing companies around the world. Over 160 forum participants voted to accept the specification. Today it is the most common DVD format in the computer industry.

DVD-RAM drives read DVD-ROM discs. In turn, DVD-RAM discs can only be read by so-called third-generation DVD-ROM drives produced since mid-1999.

The first generation of DVD-RAM discs held 2.6 GB per side. Modern second-generation drives carry 4.7 GB per side or 9.4 GB for a two-sided version.

Two types of single-sided DVD-RAM discs are available - in a cartridge and without a cartridge. Disks in a cartridge are mainly intended for household video equipment, where it is necessary to exclude the influence of external factors during intensive manual use. Cartridges, in turn, can be of two types - openable and solid.

The most important advantages of DVD-RAM format discs are the ability to be rewritten up to 100,000 times and the presence of a recording error correction mechanism.

The largest number of rewrite cycles among all DVDs, an error correction mechanism and random access to the disk, both during writing and reading, predetermined the maximum efficiency of this format in secondary storage devices. The vast majority of mass storage devices - robotic DVD libraries - use precisely this technology.

DVD-RAM discs can be used to record and play streaming video on equipment that supports the DVD-VR specification (see below).

Ш DVD+RW (Digital Versatile Disc ReWritable)

The DVD+RW format is promoted only by its developers - Hewlett-Packard, Mitsubishi Chemical, Philips, Ricoh, Sony and Yamaha (not supported by the DVD forum).

DVD+RW discs can record streaming video or audio, as well as computer data. DVD+RW discs can be rewritten approximately 1000 times.

Based on DVD+RW, a streaming video recording format has been created - DVD+RW Video Format. Devices and discs operating in this format are positioned on the market as fully compatible with equipment operating in DVD-Video formats. This means that DVD+RW discs containing video content can be played on older consumer DVD equipment.

Philips announced the launch of its DVD video recorder in September 2001. DVD+RW discs recorded on this device can also be read by conventional DVD-Video players. This solution was proposed as a response to the DVD-VR specification adopted by the DVD forum (see below).

Ш DVD-RW (Digital Versatile Disc ReRecordable)

There are other names for this format: DVD-R/W and less commonly DVD-ER.

DVD-RW is a rewritable format developed by Pioneer. DVD-RW format discs hold 4.7 GB per side, are available in single-sided and double-sided versions and can be used to store video, audio and other data.

DVD-RW discs can be rewritten up to 1000 times. Unlike DVD+RW and DVD-RAM formats, DVD-RW discs can be read on first-generation DVD-ROM drives.

TDK claims that its DVD-RW discs have a lifespan of approximately 100 years.

• · Write-once DVD formats
• Ш DVD-R (Digital Versatile Disc Recordable)

DVD-R is a write-once format developed by Pioneer. Devices based on this format were the first to record DVDs. The recording technology is similar to that used in CD-R and is based on an irreversible change under the influence of a laser in the spectral characteristics of an information layer coated with a special organic composition.

DVD-R discs can record computer data, multimedia programs, and video/audio information. Depending on the type of information recorded, discs can be read on other types of devices compatible with the recorded format, including DVD-Video video players and most DVD-ROM drives. Single-sided DVD-R discs hold 4.7 or 3.95 GB per side. Double-sided discs are only available in 9.4 GB total capacity (4.7 GB per side). Currently, the format does not support dual-layer recording technology.

The durability of DVD-R discs is estimated at over 100 years. To protect against illegal copying, two specifications have been developed: DVD-R(A) and DVD-R(G). These two versions of the same specification use different laser wavelengths when recording information. Thus, discs can only be written on equipment that meets their specifications. Disc playback can be performed equally successfully on any equipment that supports the DVD-R format.

DVD-R(A) (DVD-R for Authoring) is used in professional applications. In particular, support for a special format (Cutting Master Format) allows you to use these discs to record the original replica of information (premastering) instead of the usual use of DLT tapes for these purposes.

DVD-R(G) (DVD-R for General) is intended for wider use. Disks of this format are protected from the possibility of bit-by-bit copying of information onto them from other disks. The format is supported in mass storage devices (for example, in robotic DVD libraries offered by Pioneer itself).

The DVD-VR specification is based on DVD-RAM and is supported by the DVD Forum. The DVD-VR format allows you to record up to 2 hours of high-quality MPEG-2 video in real time on a single-sided 4.7 GB DVD-RAM disc and provides capabilities such as editing already recorded video footage and recording various types of still images. Electronics based on this format are produced, for example, by Panasonic, Toshiba, Samsung, Hitachi.

“Option 1 For long-term storage of information, the following is used: RAM; external memory; drive; CPU. In the operating system..."

Option 1

RAM;

external memory;

drive;

CPU.

question mark (?)

file creation time;

file size;

file creation location.

A spreadsheet is:

application program for processing code tables;

application program for processing table-structured data;

a computer device that controls its resources when processing tabular data;

a system program that manages computer resources when processing tables.

The driver is

long-term storage device

a program that controls a specific external device

input device

output device

How much information does the message contain that one of the 16 students in the group is the winner of the Informatics Olympiad?

1024 bytes.

MARK THE CORRECT ANSWER

Mysterious Brain Rescue

Master Boot Record

437451552070Answer:

A) 12; B) 16; C) 8; D) 10

A) 12; B) 16; C) 8; D) 10

A) 43; B) 61; C) 49; D) 56

Option 2

The main elemental base of first generation computers are:

semiconductors;

electromechanical circuits;

ultra-large-scale integrated circuits;

vacuum tubes.

In what PC device is information processed?

external memory

CPU

A device for entering information from a sheet of paper is called:

For long-term storage of information is used:

RAM;

external memory;

drive;

CPU.

In the Windows operating system, a file's own name cannot contain the character

question mark (?)

comma (,) period (.) addition sign (+) The file name extension, as a rule, characterizes:

the type of information contained in the file;

file creation time;

file size;

file creation location.

MARK THE CORRECT ANSWER

7. What do these pictures have in common?

A) logos of popular browsers

B) operating system logos

C) logos of graphic editors

D) text editor logos

8. Check the format of the vector drawing.

A) *gif; B) *cdr; C) *jpeg; D) *png9. Information capacity is...

the maximum possible amount of data that a given memory device can store

time interval from the moment the information request is sent until the result is received on the data bus

the amount of data transferred per unit of time after the immediate start of the read operation (i.e., without taking into account the preparatory stage)

10. Which of the following programs is an antivirus program?

A) Konqueror; B) Nero; C) Avira; D) FineReader11. What data type is char in Pascal?

A). Logical; IN). Whole; WITH). Symbolic; D). Listable

12. What is NOT an input device?

A) touch panel; B) scanner; C) microphone; D) plotter

13. What does the abbreviation MBR mean?

Mysterious Brain Rescue

Master Boot Record

Main Basic ReloadMinimal Be Restructure

4787900335915Select answer:

A) 12; B) 16; C) 8; D) 10

00Select answer:

A) 12; B) 16; C) 8; D) 10

14. The algorithm below uses integer variables k and m. Determine the value of the variable m after executing this algorithm:

15. What is the name of the science of methods for ensuring confidentiality, data integrity (the impossibility of changing information unnoticed), authentication (verifying the authenticity of authorship or other properties of an object), as well as the impossibility of renouncing authorship?

A) kryptonics; B) cryptography; C) cryptanalysis; D) cryptology16. Determine the required amount of video memory for graphics mode with a resolution of 1024x768 pixels and 16-bit color depth.

A) 1,574 KB; B) 1,536 bytes; C) 1,536 KB; D) 1,574 MB

17. The extensions *aifc, *aac, *ogg have:

A) video files; B) graphic files; C) audio files; D) text files

18. Only cars and motorcycles are parked in the parking lot. In total, there were 50 vehicles in the parking lot, of which: 32 cars and 15 motorcycles. Afterwards, 11 more cars arrived. How many vehicles are there in the parking lot in decimal notation?

A) 43; B) 61; C) 49; D) 56

1. THEORETICAL QUESTIONS BY SECTIONS AND TOPICS

2nd semester 1st year

Computer presentations. Basic requirements when creating a presentation

What parameters are selected simultaneously for all presentation slides?

What parameters are selected individually for each presentation slide?

Why is design necessary in presentations? How to choose a BACKGROUND for a slide

What determines the LAYOUT of a slide. Which layouts are most commonly used?

What is the difference between animation and sound in the PROCESS OF CHANGING SLIDES from animation and sound in the PROCESS OF OBJECTS APPEARING on the slide.

How can you arrange transitions between slides in an interactive presentation?

Purpose of text editors. List which text editors are used when working with documents.

What operation in a text editor provides automatic search and replacement of words throughout the document.

What color is used to highlight a spelling error in the text, and what color is used to highlight a syntactic error?

What you need to install before printing a document

What is the main object in the text. What is a font? What fonts differ in the way they are presented on a computer?

Which fonts are easier for the eye to perceive? What is the unit of font size?

What types of data can be stored in Excel spreadsheet cells. Advantages of Excel tables over regular tables.. How the cell address in a spreadsheet is determined. What you can't delete in an Excel spreadsheet.

What caused the creation of computer networks. What networks represent to users

LOCAL networks. NETWORK TOPOLOGY

What is a server-based network?

WHAT IS IT USED TO connect computers to?

GLOBAL computer network INTERNET, THEIR CLASSIFICATION

This ensures the reliability and stability of the GLOBAL computer network. What is an IP address

What Internet providers provide. List the WAYS to connect to the Internet. What determines the actual speed of your Internet connection?

Answers to assignments

Question number

Option 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Option 1 B A A B B C D B A C C D B A B C C A

Option 2 D C C B A A D B A C C D B A B C C A

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“An example of an act of implementation into production “APPROVED” General Director of JSC BelVTI A.V.Kirpichnik _._.2013 M.P. I approve the Vice-Rector for Academic Affairs and Social Affairs of BSUIR _ A.A. Khmyl_._.2013 MP ACT OF IMPLEMENTATION (USE) of the results of scientific research...”

INTRODUCTION

Information storage devices (external memory) are computer components that allow you to store large amounts of information for an almost unlimited time without consuming electricity (non-volatile).

The first such devices for PCs were Floppy disk drives (FDD) and removable floppy disks - first five-inch (5.25") with a capacity of 360 KB and 1.2 MB, then three-inch (3.5") with a capacity of 1.44 MB. Currently rarely used due to the widespread use of flash memory devices with a capacity of several gigabytes.

A characteristic feature of external memory is that its devices operate with blocks of information, but not with bytes or words, as RAM allows. These blocks usually have a fixed size, a multiple of a power of 2. A block can be written from internal memory to external memory or back only in its entirety, and a special procedure (subroutine) is required to perform any exchange operation with external memory. Exchange procedures with external memory devices are tied to the type of device, its controller and the method of connecting the device to the system (interface).

External memory is used for long-term storage of large amounts of information. In modern computer systems, the most commonly used external memory devices are:

* hard magnetic disk drives (HDD)

* floppy magnetic disk drives (FMD)

* optical drives

* magneto-optical storage media.

BASIC CONCEPTS

External memory is memory implemented in the form of devices external, relative to the motherboard, with different principles of information storage and types of media intended for long-term storage of information. In particular, all computer software is stored in external memory. External memory devices can be located both in the computer system unit and in separate cases. Physically, external memory is implemented in the form of drives.

Drives are storage devices designed for long-term (which does not depend on power supply) storage of large volumes of information. The capacity of drives is hundreds of times greater than the capacity of RAM or even unlimited when it comes to drives with removable media.

A medium is a physical medium for storing information; in appearance it can be disk or tape. Based on the principle of storage, magnetic, optical and magneto-optical media are distinguished. Tape media can only be magnetic; disk media uses magnetic, magneto-optical and optical methods for recording and reading information.

CLASSIFICATION OF LONG-TERM INFORMATION STORAGE DEVICES

External storage devices are used as information storage devices, which are implemented in the form of appropriate technical means for storing information. All drives used in PCs are unified in design. Their standard sizes are standardized: the width and height of the devices are most strictly specified, the depth is limited only by the maximum permissible value. Such standardization is necessary to unify the structural compartments of PC cases.

External memory can be random access or sequential access. Random access memory devices allow access to an arbitrary block of data in approximately the same access time. Sequential memory devices allow data to be accessed sequentially, i.e. In order to read the desired memory block, it is necessary to read all previous blocks.

The following main types of memory devices are distinguished:

1. Hard magnetic disk drives (hard drives, HDDs) - non-removable hard magnetic disks. They refer to external storage devices with direct access to data and are divided into internal ones, installed in the computer system unit, and external (portable) in relation to the system unit.

2. Floppy disk drives (floppy disk drives, floppy disk drives) - devices for writing and reading information from small removable magnetic disks (floppy disks), packaged in a plastic envelope (flexible for 5.25-inch floppy disks and hard for 3.5-inch floppy disks ). They refer to external storage devices with direct (random) access to data stored on a magnetic disk and are intended for long-term storage of relatively small amounts of information.

3. Optical disk storage devices are external storage devices with direct (random) access to data and are designed for long-term storage of relatively large volumes of information (hundreds of megabytes and tens of gigabytes).

4. Information storage devices based on flash memory refer to external storage devices with direct (random) access to data and are designed for long-term storage of relatively small amounts of information (several gigabytes).

5. Magnetic tape drives (MTL) - devices for reading data from magnetic tape, which belong to external storage devices with sequential access. Such drives are quite slow, although they have a large capacity. Modern devices for working with magnetic tapes - streamers - have an increased recording speed of 4-5 MB per second. There are also devices that allow you to record digital information on video cassettes, which allows you to store 2 GB of information on 1 cassette. Magnetic tapes are commonly used to create data archives for long-term storage of information.

6. Punched cards - cards made of thick paper and punched tape - reels of paper tape on which information is encoded by punching (perforating) holes. Serial access devices are used to read data.

Currently, devices with sequential access to GPS data are obsolete and are not used, so we will not consider them in detail.

EXTERNAL MEMORY Used for long-term storage of information Solid-state storage media Hard magnetic disk drives (HDD) HARDWARE IMPLEMENTATION Magnetic tape drives – “Streamers” Laser disk drives (CD, Compact Disk, etc.) Storage medium – recording medium/ reading and storing information.

Variant of classification of storage media used in computer technology Storage media for computers Magnetic tape media Optical disk media Magneto-optical flash media

The main type of external memory is magnetic memory. Magnetic recording At the end of 1898, Dane Valdemar Poulsen proposed a device for magnetic recording of sound on steel wire. 30 years later, the German engineer Fritz Pfleumer introduced a sound recording device with a carrier in the form of a paper tape, on which a thin steel coating was applied. In 1932, the German company AEG demonstrated the first sound recording device, which was called Magnetophon. Magnetic tape has the main disadvantage of being able to demagnetize during long-term storage and has an uneven frequency response (different recording sensitivity at different frequencies). In addition, any magnetic tape has its own noise (physical properties of the magnetic layer and methods of recording and playing back sound).

The principle of magnetic recording is the effect of an electromagnetic field on the ferromagnetic material of a magnetic tape, carried out during recording, as well as rewriting of an analog signal. The magnetic field changes during the recording process in accordance with changes in the electrical signals. Electrical vibrations from the sound source are fed to the recording head and excite a magnetic field of sound frequency (20 Hz - 20 kHz) in it. Under the influence of this field, individual sections of the magnetic tape are magnetized, which is uniformly moved along the recording, erasing and playback heads (Fig.).

To record and playback, as well as use various data on machine-readable storage media, the conversion of an analog (sound and video) signal into digital form is used. This technology is called information digitization. The principle of digitization (coding) of sound is to convert continuous amplitude-frequency audio and video signals of different magnitudes into an encoded sequence of numbers representing discrete values ​​of the amplitudes of this signal, taken after a certain period of time. To do this, it is necessary to measure the signal amplitude at certain time intervals and determine the average signal amplitude at each time interval. According to Shanon's (Kotelnikov) theorem, this period of time (frequency) must be no less than twice the maximum frequency of the transmitted sound signal (Fig.).

This frequency is called the sampling frequency. Sampling is the process of taking samples of a time-continuous signal at equally spaced points in time that make up the sampling interval. During the sampling process, the level of the analog signal is measured and stored. Amplitude Frequency (Hz) Fig. 13. Convert analog signal to digital. The rarer (smaller) the time intervals, the higher the quality of the encoded signal.

Tape drives Tape media are used for backup to ensure data safety. A streamer is used as such devices (Fig.), and as a storage medium they use magnetic tapes in cassettes and tape cartridges. Typically, magnetic tape is written to byte by byte, with the domain corresponding to a binary unit. If the reader does not detect it, then the resulting value corresponds to zero.

The recording system for magnetic disks and floppy disks is somewhat similar to the recording system for records. Unlike the latter, recording is carried out not in a spiral, but on concentric circles - tracks (“tracks” - traks), located on both sides of the disk and forming, as it were, cylinders. The circles, in turn, are divided into sectors (Fig.). Each sector of a floppy disk, regardless of the size of the track, has the same size, equal to 512 bytes, which is achieved by different recording densities: lower on the periphery and higher closer to the center of the floppy disk.

Magneto-optical storage medium is an external, highly reliable device for transferring and storing information. Magneto-optical disks (MO) appeared in 1988. The MO disk is enclosed in a plastic envelope (cartridge) and is a random access device. It combines magnetic and optical principles of information storage and represents a polycarbonate substrate (layer) 1.2 mm thick, on which several thin-film magnetic layers are applied (Fig.). Recording with a laser at a temperature of approximately 200 o. C on the magnetic layer occurs simultaneously with the change in the magnetic field. Rice. Composition of the MO disk.

Data recording is carried out by a laser in a magnetic layer. Under the influence of temperature at the heating point in the magnetic layer, the resistance to polarity change decreases, and the magnetic field changes the polarity at the heated point to the corresponding binary unit. At the end of heating, the resistance increases, but the established polarity is maintained. Erasing creates equal polarity in the magnetic field, corresponding to binary zeros. In this case, the laser beam consistently heats the erased area. Reading of the recorded data in the layer is carried out by a laser with a lower intensity, which does not lead to heating of the read area. In this case, unlike CDs, the surface of the disc is not deformed.

A compact optical disc (CD) is a plastic disc with a special coating that digitally stores recorded information. Due to the change in the speed of its rotation, the track relative to the reading laser beam moves at a constant linear speed. At the center of the disk the speed is higher, and at the edge it is slower (1.2–1.4 m/sec). CD uses a laser with radiation wavelength = 0.78 µm. Digital information “burned” by a laser is stored in the form of “pits” – lines 0.6–0.8 microns wide and 0.9–3.3 microns long. There are three main types of CDs: ● CD-ROM, which are usually recorded at the factory by stamping from a matrix; ● CD-Rs used for single or multiple laser recording sessions; ● CD-RW, designed for multiple write-erase cycles.

In CD-R (Compact Disk Recordable), on top of a reflective layer of gold, silver or aluminum, there is an organic layer of special low-melting plastic. Because of this, such a disk is sensitive to heat and direct sunlight. CD-RW also uses an organic composition as an intermediate layer, but it is capable of transitioning from a crystalline (transparent to laser) state to an amorphous one when subjected to strong heating. Low heat returns it back to the crystalline state. This is how rewriting occurs.

DVD In early 1997, a compact disc standard called DVD (Digital Video Disc) appeared, intended primarily for recording high-quality video programs. Subsequently, the abbreviation DVD received the following meaning - Digital Versatile Disc (universal digital disk), as it more fully corresponds to the capabilities of these discs for recording audio, video, text information, PC software, etc. DVD provides higher image quality than CD. They use a laser with a shorter radiation wavelength = 0.635–0.66 µm. This allows you to increase the recording density, i.e. reduce the geometric dimensions of the pits to 0.15 µm and the track pitch to 0.74 µm.

The recording density of optical discs is determined by the wavelength of the laser, that is, the ability to focus a beam with a spot whose diameter is equal to the wavelength on the surface of the disc. Following DVD, Blu-Ray devices appeared at the end of 2001, allowing operation in the blue region of the spectrum with a wavelength of 450–400 nm.

To increase the capacity, fluorescent disks are also used - FMD (Fluorescent Multilayer Disk). The principle of their operation is to change the physical properties (appearance of fluorescent glow) of certain chemical substances under the influence of a laser beam (Fig.). Here, instead of CD and DVD technologies that use a reflected signal, light is emitted directly from the information layer under the influence of a laser. These discs are made from transparent photochrome. Under the influence of laser radiation, a chemical reaction occurs in them, and individual sections of the information layer (“pits”) are filled with fluorescent material. This method can be considered a volumetric data recording method. To a greater extent, such recording is possible using three-dimensional holography, which now allows up to 1 TB of data to be placed in a crystal the size of a sugar cube.

There are two main types of Flash memory used: NAND and NOR (logical NOR function) and NAND (logical NAND function). The NOR structure consists of parallel-connected elementary information storage cells. This organization of cells provides random access to data and byte-by-byte recording of information. The NAND structure is based on the principle of sequential connection of elementary cells that form groups (16 cells in one group), which are combined into pages, and pages into blocks. With this construction of a memory array, accessing individual cells is impossible. Programming is performed simultaneously only within one page, and when erasing, access occurs to blocks or groups of blocks.

NOR chips work well together with RAM, so they are more often used for BIOS. When working with relatively large data sets, write/erase processes in NAND memory are much faster than in NOR memory. Since 16 adjacent NAND memory cells are connected in series, without contact gaps, a high density of cells on the chip is achieved, which allows for greater capacity at the same technological standards. Since the mid-1990s. NAND chips appeared in the form of solid state disks (Solid State Disk, SSD). To compare, the access time for SDRAM is 10–50 μs, for flash memory it is 50–100 μs, and for hard drives it is 5000–10000 μs.

Samsung Solid State Hard Drive. The read speed from such a disk is 57 MB/s, and the write speed to it is 32 MB/s. SSD power consumption is less than 5% of traditional hard drives, increasing battery life of laptops by more than 10%. SSDs provide ultra-high reliability of data storage and have proven themselves in conditions of extreme temperatures and humidity. St. Petersburg company “Simply. Soft" offered a Flash driver. RAID for combining two flash drives into a RAID array.

Flash memory is a portable non-volatile storage device. The following flash memory standards are commonly used: Compact. Flash, Smart. Media, Memory Stick, Floppy Disks, Multi. Media Cards, etc. They can be used instead of floppy disks, laser and magneto-optical compact, small hard drives. Modern removable flash memory devices provide high data exchange speeds (Ultra High Speed) - more than 16.5 Mbit/s. To connect to a computer's USB port, special USB Flash Drives are used (Fig.), which are small-sized mobile data storage devices that do not have moving or rotating mechanical parts.

Holography is a photographic method of recording, reproducing and transforming wave fields. It was first proposed in 1947 by the Hungarian physicist Dennis Gabor. In the 1960s, with the advent of the laser, it became possible to accurately record and reproduce volumetric images in a lithium niobate crystal. Since the 1980s, with the advent of compact discs, holographic information storage devices based on laser optics have become one of the external memory technologies. Holographic memory represents the entire volume of the storage medium of the carrier, while data elements are accumulated and read in parallel.

Modern holographic storage devices are called HDSS (holographic data storage system). They contain: a laser, a beam splitter for dividing the laser beam, mirrors for directing laser beams, a liquid crystal panel used as a spatial light modulator, lenses for focusing laser beams, a lithium niobate crystal or photopolymer as a storage device, a photodetector for reading information (Fig.) .

Many people wonder: what is used for long-term storage of information? So, the structure of my story is as follows:

1. what serves for long-term storage of information;
2. types of information.

What is used for long-term storage of information

The main information process is the process of storing information, that is, a method through which it is possible to transmit data across space and time. In order to save information for a long time, devices or devices are used that depend on the type of information being stored. In order to ensure the orderliness of this process, the availability of information systems equipped with procedures for searching, posting, and editing information is necessary. The main distinguishing feature of information systems is these key procedures.

Programmers determine: in order to save information for a long time, external storage devices should be used. This can be a storage device or media of every type imaginable.

Types of information

In addition to the above, it should be said about what types of information there are. So, the information could be as follows:

• text;
• pictorial;
• numerical;
• sound recording;
• video recording.

The most common way to save information today is the text type. True, this storage method is not reliable and durable. Graphic, or pictorial type is the most ancient method of storing information; these are all kinds of diagrams, graphs and drawings.

In order to store information for a long time and transfer it from one storage medium to another, hard drive devices, DVDs, CD drives, flash drives, and floppy drives are used.

A hard drive is a means of permanently storing information and programs on a computer.

Floppy disk is the principle of recording data on magnetic tapes. Such a device can hold information up to 600 pages of a text document.

The CD is an optical recording principle. You can even write down an encyclopedia, which contains many volumes. Flash memory is a device that does not require electrical power.