Funds long-term storage and data storage (external storage device) provide recording and reading of large amounts of information, which can be used as: program texts in high-level languages, programs in machine codes, data files, etc. As external storage devices in a PC, floppy disk drives (floppy disk drives) and hard disk drives (HDD) of the "hard drive" type are mainly used.

Floppy disk drives are the main external memory devices of personal computers. The information carrier in the floppy disk drive is a flexible magnetic disk (HMD) made of a synthetic film coated with a wear-resistant ferro-varnish. Information on the KMT is placed in a sequential code on concentric circles (tracks), each of which is divided into sectors. The sector is the unit of data exchange between the OP and the NGMD. One sector can hold 128,256, 512 or 1024 bytes of data. In a PC, the listed data formats can be installed programmatically.

HMD has a locating hole (UO) for fixing the disc in the drive and an index hole (IO) for identifying the beginning of tracks. To protect against the adverse effects of the external environment, the HMD is placed in a rectangular envelope that has a slot for supplying magnetic heads (PMG), a slot for an index hole (FID) and a hole for attaching the HMI in a disk drive (OKD). The information that is recorded on the KMT, according to its purpose, is divided into service and work. Service information is used to control and synchronize the operation of the floppy disk drive. It, in turn, is subdivided into track-identifying information and sector-identifying information. Operational information represents user data.

The capacity of the floppy disk drive in the PC is 160 KB and more, depending on the number of magnetic heads in the drive and the density of data recording on the disk drive. There are the following types of floppy disk drives: with single and double recording density; one-sided - with one and double-sided - with two MG. In double-sided floppy drives, both surfaces of the GMI can be used for writing and reading data. In accordance with the types of floppy disk drives, the corresponding marking of the GMD was also adopted: SS - one-sided single-density disc; SD - double density single sided disc; DD is a double-sided disc, double density.

Along with the floppy disk drive, the developed models of personal computers are also equipped with hard drives on magnetic disks of the "hard drive" type. Their distinctive features are a hermetically sealed single design of the disk, magnetic read-write heads and their drives, a small gap (compared to conventional UDM) between the magnetic heads and the disk surface (0.5 μm), a small pressure of the magnetic head (10 g by compared to 350 g in conventional LMD), small thickness of the magnetic disk.

The hermetically sealed design doubles the operational reliability as compared to conventional LMD. Reducing the gap between the disk surface and the magnetic heads significantly increases the longitudinal and transverse recording density. LMDs of the "Winchester" type are considered the third generation of LMDs and have characteristics close to their limit. So, an NMD with a diameter of 356 mm on one surface can include up to 1770 tracks (1300 MB of information).

Development of modems.

The first information processing systems, in which telegraph equipment was used to connect subscribers to a computer, were created in the early 60s. In such systems, transmission was carried out using conventional telegraph equipment at relatively low rates, not exceeding 110 bit / s.

The next stage in the development of data transmission systems was the development of modems that provide the ability to transfer binary information over telephone lines.

Modem- an electronic device equipped with the functions of modulating data at the transmitting end of the communication line and demodulating at the receiving end of the communication line. Modulating a signal means converting a signal to a form that allows it to be transmitted over long distances. For example, a typical acoustic modem is equipped with two bowl-shaped receptors on which a telephone receiver is placed. The modem is connected to a computer, from which it receives information in the form of a sequence of binary signals - bits. However, the telephone is designed to transmit audio frequency, and the binary bits are just electrical impulses not audible to the human ear. Therefore, electrical impulses are pre-converted in the modem into audio signals, and then transmitted over telephone lines. At the other end, the reverse process of converting audio frequency signals into a sequence of binary electrical impulses - bits suitable for computer operation. Such transformations are called modulation and demodulation, the described device is just the simplest modem.

The first samples of modems had a relatively low data transfer rate, but later the transfer rate over switched channels increased to 1200 bit / s in duplex mode - the mode of simultaneous input and output of information, or up to 9600 bit / s in half-duplex mode - a mode designed for sequential input and information output.

In the mid-60s, the intensive development of specialized information processing systems based on dedicated channels began. Such systems are created to meet the needs of individual organizations that own both computing resources and communication channels. However, the operation of such systems has shown that the computing resources and communication channels used in them are not used effectively enough, the systems turn out to be expensive and not well adapted to changing conditions. The need for many users to access powerful computers for relatively short periods of time has emerged.

All this has led to the development of shared data transmission systems, in which many users can connect through public communication networks of their choice to various information processing facilities.

Keyboard.

The keyboard is an important and versatile device for entering information into a computer.

According to the arrangement of the keys, desktop keyboards are divided into two main types, which functionally are in no way inferior to each other. In the first version, the function keys are located in two vertical rows, and there are no separate groups of cursor control keys. There are 84 keys in such a keyboard.

The second version of the keyboard, which is usually called improved, has 101 or 102 keys. Almost all desktop personal computers are equipped with this type of keyboard today. Professionals do not like this keyboard due to the fact that you have to reach far to the function keys, to the topmost row of keys across the entire letter keyboard. However, the number of function keys in the improved keyboard is not 10, but all 12.

V laptop the keyboard is usually a built-in part of the design.

The location of the letter keys on computer keyboards standard. Today, the QWERTY standard is widely used - for the first six Latin letter keys of the top row. It corresponds to domestic standard QSUKEN the arrangement of the keys in the Cyrillic alphabet, almost similar to the arrangement of the keys on a typewriter.

Standardization in the size and position of the keys is needed so that the user can work in a “blind way” on any keyboard without retraining. The blind ten-finger method of work is the most productive, professional and efficient. Alas, the keyboard, due to the low productivity of the user, is today the "bottleneck" of a high-speed computing system.

Working with the keyboard is very simple and intuitive. In order to assign a certain byte of information to each character on the keyboard, a special table of ASCII codes (American Standard Code for Information Interchange) is used, the American standard for codes for the exchange of information used on most computers.

When a key is pressed, the keyboard sends an interrupt signal to the processor and causes the processor to suspend and switch to the keyboard interrupt routine.

In this case, the keyboard in its own special memory remembers which key was pressed (usually, the keyboard memory can store up to 20 codes of pressed keys if the processor does not have time to respond to the interrupt). After sending the code of the pressed key to the processor, this information disappears from the keyboard memory.

In addition to pressing, the keyboard also notes the release of each key, sending the processor its interrupt signal with the corresponding code.

Entering characters from the keyboard is carried out only at the point on the screen where the cursor is located. The cursor is a rectangle or a line of contrasting color one character long.

Special keyboard keys: Special (service) keys perform the following main functions: (ENTER) - entering commands for execution by the processor; (ESC) - cancellation of any action; (TAB) -moves the cursor to the tab stop; (INS) -switching the mode of inserting a character at the cursor position to the mode of backing up a character at the cursor position;

(DEL) -deleting a character at the cursor position;

(BACKSPACE) -delete the character to the left of the cursor;

(HOME) -moves the cursor to the beginning of the text;

(END) -moves the cursor to the end of the text;

(PGUP) -move the cursor one screen page up through the text;

(PGDN) -moves the cursor one screen page down the text;

(ALT) and (CTRL) -when these keys are pressed simultaneously with any other, the action of the latter is changed;

(SHIFT) - holding this key down will change the case;

(CAPS LOCK) -fixing / unlocking the case of capital letters;

INTRODUCTION

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

The first such devices for PCs were floppy disk drives (FDD) and removable diskettes - first five-inch (5.25 ") capacity of 360 KB and 1.2 MB, then three-inch (3.5") capacity of 1.44 MB. Currently, they are 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 bytes or words, as the RAM allows. These blocks are usually of a fixed size, a multiple of a power of 2. The block can be rewritten from internal memory to external or back only as a whole, and a special procedure (subroutine) is required to perform any exchange operation with external memory. The 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 disk drives (HDD)

* floppy disk drives (floppy disk drives)

* optical drives

* magneto-optical data carriers.

BASIC CONCEPTS

External memory is a memory implemented in the form of external, relative to the motherboard, devices with different principles of information storage and types of media, designed 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.

Storage devices are storage devices designed for long-term (which does not depend on power supply) storage of large amounts of information. Storage capacities are hundreds of times larger than RAM, or even unlimited when it comes to removable media.

A medium is a physical medium for storing information, outward appearance can be disk or tape. According to the principle of memorization, magnetic, optical and magneto-optical carriers are distinguished. Tape media can only be magnetic; in disk media, magnetic, magneto-optical and optical methods of recording and reading information are used.

CLASSIFICATION OF LONG-TERM 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 a PC are unified in design. Their standard sizes are standardized: the width and height of the devices are set most rigidly, 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 and sequential access. Random access memory devices allow an arbitrary block of data to be accessed in approximately the same access time. Sequential memory devices allow data to be accessed sequentially, i.e. in order to read the desired block of memory, it is necessary to read all the previous blocks.

There are the following main types of memory devices:

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

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

3. Information storage devices on optical disks are external storage devices with direct (random) access to data and are intended for long-term storage of relatively large amounts 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 intended for long-term storage of relatively small amounts of information (units of gigabytes).

5. Magnetic tape drives (TAP) are magnetic tape readers, which are external storage devices with sequential access. Such drives are quite slow, albeit with a large capacity. Modern devices for working with magnetic tapes - streamers - have an increased write speed of 4-5MB 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 - rolls 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 floppy disk drive data are outdated and not used, so we will not consider them in detail.

“Option 1 For long-term storage of information 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;

where the file was created.

A spreadsheet is:

application program for processing code tables;

an application program for processing data structured in the form of a table;

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

a system program that manages computer resources when processing tables.

The driver is

long-term storage device

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 computer science Olympiad?

1024 bytes.

MARK CORRECT ANSWER

Mysterious Brain Rescue

Master Boot Record

437451552070 Answer:

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

Basic element base First generation computers are:

semiconductors;

electromechanical circuits;

very large-scale integrated circuits;

vacuum tubes.

In which PC device is information processing carried out?

external memory

CPU

The device for inputting information from a sheet of paper is called:

For long-term storage of information is used:

RAM;

external memory;

drive;

CPU.

In the operating system Windows native filename cannot contain character

question mark (?)

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

the type of information contained in the file;

file creation time;

file size;

where the file was created.

MARK CORRECT ANSWER

7. What do these pictures have in common?

A) logos of popular browsers

B) operating system logos

C) graphic editor logos

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 of sending the request for information to the moment of receiving the result on the data bus

the amount of data transferred per unit of time after the immediate start of the read operation (i.e., excluding the preparatory stage)

10. Which of the following programs is anti-virus?

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

A). Logical; V). Whole; WITH). Symbolic; D). Enumerable

12. What is NOT related to input devices?

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

13. What does MBR stand for?

Mysterious Brain Rescue

Master Boot Record

Main Basic ReloadMinimal Be Restructure

4787900335915Select an answer:

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

00Select answer:

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

14. The algorithm described below uses the 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 of ensuring confidentiality, data integrity (the impossibility of imperceptible changes to information), authentication (verification of the authenticity of authorship or other properties of an object), as well as the impossibility of rejection of authorship?

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

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

17. 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. There were 50 vehicles in the parking lot, of which 32 were cars and 15 were motorcycles. After that, 11 more cars arrived. How many vehicles are in the parking lot in decimal notation?

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

1. THEORETICAL QUESTIONS ON SECTIONS AND TOPICS

2 semester 1 course

Computer presentations. Basic requirements when creating a presentation

What parameters are selected simultaneously for all slides in the presentation

What parameters are selected individually for each slide of the presentation

Why do you need design in presentations? How to choose a background for a slide

What determines the layout of the slide. What layouts are used more often.

What is the difference between animation and sound in the PROCESS OF CHANGING SLIDES from animation and sound in the PROCESS OF APPEARANCE OF OBJECTS on a slide?

How can you organize transitions between slides in an interactive presentation

Appointment of text editors. List what text editors are used in working with documents.

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

What color is the spelling error in the text, and what is the syntactic

What needs to be set 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 to see with the eye. What is the unit of measure for font size

What types of data can be stored in cells of an Excel spreadsheet. Advantages of Excel spreadsheets over regular tables. What determines the cell address in spreadsheet... What cannot be deleted in an Excel spreadsheet.

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

LOCAL networks. TOPOLOGY OF NETWORKS

What is a server-based network

WITH THE HELP OF WHAT the computers are connected

GLOBAL computer network INTERNET, THEIR CLASSIFICATION

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

What Internet Service Providers Provide. List the WAYS of connecting to the Internet. What determines the real speed of the Internet connection.

Answers to tasks

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

Similar works:

“Belarusian State University of Informatics and Radioelectronics Department of Chemistry Report on laboratory work No. 6 Chemical etching of semiconductors. Determination of the density of dislocations Performed by: 1st year student of Group #__Checked: Molochko A.P. Minsk 2016 Experimental part Purpose of work: to carry out polishing and selective ... "

"An example of an act of implementation in production" APPROVED "General Director of JSC" BelVTI "A.V. Kirpichnik _._. 2013 M.P. I approve the Vice-rector for educational work and social issues BSUIR _ A.A. Khmyl _._. 2013 M.P. ACT OF IMPLEMENTATION (USE) of the results of scientific research ... "

Classification of long-term storage devices

The most common are magnetic disk drives, which are divided into hard disk drives (HDDs) and floppy disk drives (floppy disks), and optical disk drives such as CD-ROMs, CD-Rs, CD-RWs and DVD-ROM.

Detailed characteristics of long-term storage devices

Hard disk drives (HDD)

HDD is the main device for long-term storage of large amounts of data and programs. Other names: HDD, hard drive, HDD (Hard Disk Drive). Externally, the hard drive is a flat, hermetically sealed box, inside of which there are several rigid aluminum or glass round plates on a common axis. The surface of any of the disks is covered with a thin ferromagnetic layer (a substance that reacts to an external magnetic field), in fact, the recorded data is stored on it. In this case, the recording is carried out on both surfaces of each plate (except for the extreme 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 stack rotates continuously and at high frequency (4500-10000 rpm), therefore, the mechanical contact of the heads and disks is unacceptable.

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

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

• § disk rotation speed - nowadays EIDE drives are produced with a rotation frequency of 4500-7200 rpm, and SCSI drives - 7500-10000 rpm;
• § cache memory capacity - in all modern disk drives, a cache buffer is installed, which speeds up the exchange of data; the larger its capacity, the higher the likelihood that the cache will contain the necessary information that does not need to be read from the disk (this process is thousands of times slower); 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 actuator design and is approximately 10-13 milliseconds;
• § delay time is the time from the moment the head unit is positioned to the desired cylinder to the positioning of a specific head to a specific sector, in other words, it 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 within certain periods of time; maximum value this parameter is equal to bandwidth disk interface 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, than more number PIO mode, the higher the exchange rate; work in DMA (Direct Memory Access) mode allows data to be transferred directly to RAM without the participation of a processor; data transfer rate in modern hard drives fluctuates in the range of 30-60 MB / s.
• Floppy disk drives (floppy disk drives)

The floppy disk drive or disk drive is built into the system unit. Flexible media for floppy disk drives is produced in the form of floppy disks (another name for floppy disk). Actually, the carrier is a flat disc with a special, rather dense film covered with a ferromagnetic layer and placed in a protective envelope with a movable latch in the upper part. Floppy disks are mainly used to quickly transfer small amounts of information from one computer to another. Data recorded on a floppy disk can be protected from erasure or overwriting. To do this, move the small safety latch at the bottom of the floppy disk so that an open window is formed. In order to enable recording, this latch should be moved back and the window should be closed.

The main parameters of a floppy disk are technological size (in inches), recording density and total capacity. There are 3.5 "floppy disks and 5.25" floppy disks (no longer used anymore) by size. 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, it is possible to use 720 KB floppy disks. The current standard is 3.5-inch high-density HD floppy disks with a capacity of 1.44 MB.

CD-ROM drive

Beginning in 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) translates as read-only memory device based on compact discs. The principle of operation of this device is to read digital data using a laser beam, which is reflected from the surface of the disk. An ordinary CD is used as a storage medium. Digital recording on a compact disc differs from recording on a magnetic disc in 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), therefore CD-ROM drives refer to hardware multimedia. In addition to multimedia publications (e-books, encyclopedias, music albums, videos, computer games), various system and application software of large volumes (operating systems, office suites, programming systems, etc.) are distributed on CDs.

Compact discs 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 the conditions of mass production, information is recorded on a disc by extrusion on the surface of the track, in the form of a series of depressions. This approach provides binary notation information. Deepening (pit), surface (land). Logical zero can be represented by either a pet or a land. The logical unit is encoded by the transition between the pet and the 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 disc is divided into three areas. The Lead-In is located in the center of the disc and is read first. It contains the contents of the disk, the 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. Lead-Out contains the disc end mark.

For stamping, there is a special prototype matrix (master disc) of the future disc, which squeezes the tracks onto the surface. After stamping, a protective film made 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 be read data at a speed of 300 Kbytes / sec., 50-speed (50x) - 7500 Kbytes / 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 writers and CD-RW rewritable devices.

CD-R drive (CD-RECORDABLE)

Externally similar to CD-ROM drives and compatible with them in disk sizes and recording formats. Allows you to perform a one-time write and an unlimited number of reads. Data recording is carried out using a special software... The write speed of modern CD-R drives is 4x-8x.

CD-RW drive (CD-REWRITABLE)

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

· DVD drive(DIGITAL VIDEO DISK)

Digital video reader. Externally, a DVD 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 a DVD, and up to 9.4 GB. In the case of using a two-layer recording scheme, one side can already accommodate up to 8.5 GB of information, respectively, on both sides - about 17 GB. DVDs are rewritable.

DVD Perspectives

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 the "blue laser" technology - with a shorter wavelength. This will increase the recording density on discs with the ensuing improvement in other characteristics.

Calimetrics Inc introduced ML (multilevel) technology that triples the capacity of a standard DVD / CD. At the same time, there is no need to make any modifications in the mechanism and optics of the existing drives. For implementation new technology just use the chipset developed by this company. The essence of the technology lies in the ability to use as information characteristics pit depth (up to 8 levels) when working with discs. Note that a similar technology, but for CDs, is being developed by TDK in cooperation with other companies.

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

DVD-ROM discs are intended for computer use. The information is written to the disc the only time - during its production.

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

The DVD-Video format is designed for video storage and playback. Like DVD-ROM, this specification defines read-only information - playback of recordings using video players (video encoders). The specification is based on the DVD-ROM format, but provides a special way to arrange data to prevent bitwise copying of discs. Video materials in encoded form are placed on the disc during its production. DVD-video playback is possible only on consumer video players (video encoders) or on DVD drives connected to a computer. When using computer equipment, decoding of information is carried out either in hardware or by software... The modern specification provides high-quality video recording to disk (up to 2 hours in MPEG-2 compression format). And also multichannel soundtrack in 8 languages, choice of screen format, captions in 32 languages, interactive control through the on-screen menu, up to 9 angular viewing directions, protection against illegal copying, differentiation 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 multichannel sound, support for a wide range of sound quality (quantization of 16, 20, 24 bits at a frequency of 44.1 to 192 kHz), DVD playback CD players, support for additional information (including video, text, menus, splash screens, convenient navigation system), communication with web sites providing information support, expansion of opportunities when new technologies appear.

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.

• Reusable DVD formats
• W Multiple recording

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

W 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. Hardware and discs of this format were tested for 3 months in more than 20 computer manufacturing companies around the world. Over 160 forum members voted in favor of the specification. It is the most widely used DVD format in the computer industry today.

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

First generation DVD-R discs AM fit 2.6 GB per side. Modern - second - generation drives carry 4.7 GB on the side or 9.4 GB for double-sided modification.

There are two types of single-sided DVD-RAM discs available - in cartridge and without cartridge. Discs in a cartridge are mainly intended for consumer 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 discs are the ability to rewrite up to 100,000 times and the presence of a recording error correction mechanism.

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

DVD-RAM discs can be used for recording and streaming video on equipment that conforms to the DVD-VR specification (see below).

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 about 1000 times.

On the basis of 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 previously released consumer DVD equipment.

Philips announced the launch of its DVD video recorder in September 2001. The DVD + RW discs recorded on this device are also readable by regular DVD-Video players. This solution was proposed as a response to the DVD-Forum's adopted DVD-VR specification (see below).

DVD-RW (Digital Versatile Disc ReRecordable)

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

DVD-RW is a rewritable format developed by Pioneer. DVD-RW discs contain 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.

• DVD write-once formats
• W 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 on 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 the information layer covered with a special organic compound.

DVD-R discs can contain both 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 available only with a total capacity of 9.4 GB (4.7 GB per side). The format does not currently support double layer recording technology.

DVD-R discs are estimated to be over 100 years old. 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 recorded on equipment that meets their specifications. Disc playback can be performed equally well on any equipment that supports the DVD-R format.

DVD-R (A) (DVD-R for Authoring) is used in professional applications. In particular, the support of a special format (Cutting Master Format) allows using these disks for recording the original replica of information (pre-mastering) instead of the usual use of DLT tapes for these purposes.

DVD-R (G) (DVD-R for General) is intended for wider applications. Discs of this format are protected from the possibility of bitwise copying of information on them from other disks. The format is supported by mass storage devices (such as 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 can record up to 2 hours of high quality MPEG-2 video in real time onto a 4.7 GB single-sided DVD-RAM disc, and offers features such as editing of already recorded video material, recording of various types of still images. Electronics based on this format are produced, for example, by Panasonic, Toshiba, Samsung, Hitachi.