CDs. Classification

In December 1995, 10 companies united in the DVD Consortium officially announced the creation of a single unified standard - DVD. The abbreviation DVD first stood for Digital Video Disc, but later its meaning was changed to Digital Versatile Disc. The disc was fully compatible with the Red Book and Yellow Book standards.

DVD is identical in appearance to CD, but allows you to record information that is 24 times larger in volume, that is, up to 17 GB. This became possible thanks to changes in the physical characteristics of the disk and the use of new technologies. The distance between the tracks was reduced to 0.74 μm, and the geometric dimensions of the pits were reduced to 0.4 μm for a single-layer disk and 0.44 μm for a double-layer disk. The data area has increased, the physical sizes of sectors have decreased. A more efficient error correction code, RSPC (Reed Solomon Product Code), was used, and more efficient bit modulation became possible.

DVD technology provides a huge number of formats and four types of designs in two sizes. A disc of this standard can be either single-sided or double-sided. There can be one or two working layers on each side. Let's look at the main characteristics of various types of DVDs.

Disc size – 80 mm (3.1 inches).

– DVD-1 (Single-sided, single-layer) – single-sided and single-layer disc. Can contain up to 1.36 GB of information (Fig. 1.5).

– DVD-2 (Single-sided, double-layer) – single-sided double-layer disc. Contains up to 2.48 GB of information (Fig. 1.6).

– DVD-3 (Double-sided, double-layer) – a two-layer disc with one information layer on each side. Capacity – up to 2.74 GB of information (Fig. 1.7).

– DVD-4 (Double-sided, double-layer) – a disc with two information layers on each side. The capacity of such a disk is up to 4.95 GB (Fig. 1.8).

Disc size – 120 mm (4.75 inches).

– DVD-5 (Single-sided, single-layer) – single-sided single-layer disc. Contains up to 4.7 GB of information.

Rice. 1.5. Structure of DVD-1 and DVD-5.

– DVD-9 (Single-sided, double-layer) – single-sided and double-layer disc. Capacity – up to 8.5 GB.

– DVD-10 (Double-sided, double-layer) – a two-layer disc with one information layer on each side. Contains up to 9.4 GB of information.

– DVD-18 (Double-sided, double-layer) – a two-layer disc with two information layers on each side. Capable of storing up to 17 GB of information.

Rice. 1.6. Structure of DVD-2 and DVD-9.

Rice. 1.7. Structure of DVD-3 and DVD-10.

Rice. 1.8. Structure of DVD-4 and DVD-18.

Note.

The number in the disc name—DVD-1, DVD-4, DVD-10, etc.—is a rounded capacity value.

Burning single-layer DVDs is similar to burning CDs, but burning dual-layer discs is significantly different from the process described earlier.

Double-layer discs of types DVD-2 and DVD-9 have two working layers for recording information. These layers are separated using a special translucent material. To perform its function, such a material must have mutually exclusive properties: reflect the laser beam well when reading the outer layer and at the same time be as transparent as possible when reading the inner layer. At the request of Philips and Sony corporations, 3M created a material that meets the following requirements: having a reflectivity of 40% and the necessary transparency.

When reading information from such a disk, the laser beam first passes through the translucent layer, focusing on the tracks of the inner layer. Having read all the information in the inner layer, the laser beam automatically changes its focus and reads information from the translucent layer. The presence of a buffer in the DVD drive and the ability to quickly change focus allows you to continuously feed data to the motherboard.

When making a two-layer disc, the first layer, based on polycarbonates, is first stamped. Then a translucent material is applied, which in turn is covered with a film of photopolymer material. Using ultraviolet radiation, the photopolymer is hardened, and the DVD is filled with polycarbonate, which serves as a protective layer for the disc.

DVDs are 0.6mm thick. For physical compatibility with CDs, a 0.6 mm thick polycarbonate backing was additionally glued onto the DVD. In order to not only increase the thickness of the DVD to 1.2 mm, but also at the same time improve its functionality by doubling the media capacity, Toshiba created a double-sided disc (types DVD-3 and DVD-10). To get a DVD-3 disc, just glue two DVD-1s together on the label side; to obtain DVD-10, two DVD-5 are connected. Thus, by gluing two 0.6 mm thick disks together, we get one disk that is equal in thickness to a CD and has the ability to record twice as much information.

To obtain DVD-4 discs, you should glue two DVD-2, for DVD-18 - respectively, two DVD-9.

The principle of writing information to DVD-R (Digital Versatile Disk Read-only - write-once DVD) and reading from it is similar to writing and reading CD-R. When recording a DVD in special recorders, a high-power laser beam “burns” holes (pits) in the active layer. When reading information, a laser beam of normal power, freely passing through the resulting hole, is reflected from the metallized layer and hits the photosensor, and then the microprocessor.

To write and read information from DVD-RW (Digital Versatile Disk ReWritable - rewritable DVD), Phase Change Technology is used. The laser beam moves along a spiral path during recording. During the period of increased beam activity, the recording layer changes its structure, passing from a crystalline state to an amorphous one. When reading information, the detector recognizes from which surface the laser beam was reflected - crystalline or amorphous - and converts the data into a digital stream. Under the influence of a laser beam of a certain power, the active (recording) layer returns to its original state, and the disk can be rewritten many times.

The material, capable of repeatedly changing its structure, was developed by TDK and was called AVIST (Advanced Versatile Information Storage Technology - a modern universal technology for storing information).

Note.

The AVIST material in the crystalline state has a 25–35% reflective ability, and upon transition to the amorphous state it darkens and does not reflect the laser beam.

For DVD-ROM, VideoDVD, AudioDVD, etc., the UDF (Universal Disk Format) file system developed by the OSTA (Optical Storage Technology Association) is used. This file system is a development of the CD-ROM file system (CDFS or ISO 9660).

DVD technology was originally developed for recording and playing movies. VideoDVD must provide the following capabilities:

Playback of films with a duration of at least 133 minutes;

Various options for displaying widescreen video;

Up to 32 subtitle options in various languages;

Surround sound;

Copy protection and regional coding;

Viewing interactivity.

Navigation data;

Reproduction objects.

Playback objects are divided into video, audio and graphics.

To play digital video, a bit rate of 167 Mbps is required. Therefore, a 4.7 GB disk can hold four minutes of digitized video. To save at least 133 minutes of high-quality images, data compression is used. The video is encoded in a special MPEG-2 format developed by the MPEG group (Moving Picture Experts Group).

While watching films, you probably noticed that the background against which the characters move, as a rule, remains unchanged. The fact is that approximately 95% of repeated background images can be eliminated during digitization without a noticeable loss in quality, while the amount of digital bitrate is significantly reduced.

Audio is encoded and compressed using various technologies: Dolby Digital, MPEG-1 and MPEG-2. AudioDVD uses LPCM (Linear Pulse Code Modulation) technology, which does not use compression. The LPCM format allows you to transmit sound waves with the highest quality and accuracy (sampling frequency - 48 or 96 kHz, digitization depth - 16, 20 or 24 bits), using from one to eight audio channels, and obtaining a dynamic recording range of up to 120 dB. In this case, the digital data stream can be 6.144 Mbit/s.

Audio signal compression using Dolby Digital technology – AC-3 (Audio Cannels) – provides 5.1 sound (5 main audio channels and one low-frequency channel) with a range of 20–20,000 Hz. For audio compression, a special algorithm developed by Dolby is used, called Multichannel Perceptual Coding. The human hearing, depending on gender and age, perceives sounds in different frequency ranges with different sensitivity. In addition, there are certain frequencies and timbres that are difficult for all people to distinguish. With Dolby Digital technology, certain frequency ranges that are difficult for the human ear to hear are suppressed, resulting in some data loss. However, as a result, the digital stream is significantly reduced; for example, only 348 Kbps is sufficient for six channels.

Audio signal compression using MPEG-1 and MPEG-2 technologies is also associated with data loss. The MPEG-1 format is intended for mono or stereo audio only. The MPEG-2 format can be multi-channel and is capable of providing 5.1 or 7.1 surround sound.

Audio signal compression using DTS (Digital Theater System - digital theater with surround sound) technology, developed in the USA, is an alternative to Dolby Digital. The sound quality is slightly higher, the perception of sound effects is more spatially realistic, but the data flow in this case can reach 1536 Kbps.

To control the distribution of discs and protect copyright, DVD producers divided the world into six geographical zones and developed special icons and codes for each zone. The use of such regional coding of both the discs themselves and their players made it impossible to play discs from one zone on DVD drives from another zone.

Zone 1 – USA and Canada.

Zone 2 – Western Europe, Japan, South Africa, Middle East.

Zone 3 – Southeast and East Asia, including Taiwan and Hong Kong.

Zone 4 – Latin America, South America, Caribbean Islands, Australia and New Zealand.

Zone 5 - countries of the former Soviet Union, Africa (except South Africa), India, Pakistan, Mongolia and North Korea.

Zone 6 - China.

Currently, DVD player manufacturers produce so-called "multi-zone" devices that support most formats.

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Structure of CD.

DVD structure.

Rules for using CDs.

CD/DVD drive.

In the late 1970s, Sony and Philips began jointly developing a single standard for optical storage media. Philips created the laser player, and Sony developed the technology for recording on optical media. At the suggestion of the Sony Corporation, the disc size was 12 cm, since this volume made it possible to record Beethoven's entire Ninth Symphony. In 1982, a document called the Red Book published a standard for processing, recording and storing information on laser discs, as well as the physical parameters of the disc.

Note.
There is a legend that the Red Book document was named so because of the cover in which it was stored. All further CD standards were named books of different colors: Yellow Book, Orange Book, White Book, Blue Book, Green Book.

The following parameters were defined in the Red Book standard.

Physical size of the disk.

Disk structure and data organization.

Note.
All data on the disk is divided into frames. Each frame consists of 192 bits for music, 388 bits for modulation and error correction data, and one control bit. 98 frames make up one sector. Sectors are combined into a track. A maximum of 99 tracks can be recorded on a disc.

Recording data in a single stream from the center to the periphery.

Read data at a constant linear velocity (CLV).

Note.
During recording and reading of information, when the laser beam moves from the center to the periphery, the rotation speed of the disk decreases. This is necessary to ensure that the same amount of information can be read and written in the same amount of time. Therefore, without the use of CLV technology, when playing, for example, musical works, there would be a change in the speed of execution.

Due to the relatively small size of laser discs compared to vinyl records, they were called compact discs, or CD (Compact Disk) for short. The first CDs were intended for recording and playing music (in fact, that's what they were created for) and could store up to 74 minutes of high-quality stereo sound. The standard for such discs was called CD-DA (Compact Disk Digital Audio).

With the development of the computer industry, a need arose for technology that allows storing not only digital sound, but also various data on CDs. Computer programs could not fit on floppy disks, and the volume of user files became larger and larger.

In 1984, a standard called the Yellow Book was published. Sony and Philips companies reorganized the structure of CDs and began to use new error correction codes - EDC (Error Detection and Correction) and ECC (Error Correction Code). The main unit of data placement was the sector. One sector contains: 12 bytes for synchronization, 4 bytes for headers, 2048 bytes for user data and 288 bytes for error correction.

CAV (Constant Angular Velocity) technology was developed to read computer data. CAV technology allows you to read information from a disk faster than CLV technology, since the data flow increases as the laser beam moves from the center to the periphery. Modern CD drives support both technologies.

Computer laser disks were called CD-ROM - Compact Disk ReadOnly Memory (literally, “read-only memory on CDs”). In the late 1990s, the CD drive became a standard component of any computer and the vast majority of programs began to be distributed on CDs.

The consumer market was rapidly expanding, production volumes were increasing, and the largest manufacturers began developing technology that allows the user to independently record any information on a CD. In 1988, Tajio Yuden released the world's first CD-R (Compact Disk Recordable). The biggest challenge faced by CD recorder designers is finding highly reflective materials. Tajio Yuden successfully completed the task. The gold-cyanine alloy they used to make these drives had a reflectivity of over 70 %. The same company developed a method for applying an active organic layer to the surface of a disk, as well as a technology for dividing the disk into tracks.

Structure of CD

A Compact Disk (CD) is a disk with a diameter of 120 mm (4.75 inches) or 80 mm (3.1 inches) and a thickness of 1.2 mm. The depth of the stroke is 0.12 µm, the width is 0.6 µm. The strokes are arranged in a spiral, from the center to the periphery. The stroke length is 0.9–3.3 µm, the distance between the tracks is 1.6 µm. Compact discs are made up of three to six layers.

To accommodate five- and three-inch discs in the CD drive tray there are special recesses - 5 and 3 inches, respectively.

Note.

In oral speech, as well as in print, rounded values for the diameter of the disk are most often used: instead of 4.75 inches - 5, instead of 3.1 inches - 3.

A standard five-inch disc can contain 650–700 MB of information, 74–80 minutes of high-quality stereo sound with a sampling rate of 44.1 kHz and a digitization depth of 16 bits, or a huge amount of audio in MP3 format.

Three-inch disks hold about 180 MB of information.

Sometimes there are disks called “business cards” (Fig. 1.1). In appearance and size, they resemble a business card, but are actually three-inch disks, cut on both sides. From 10 to 80 MB is recorded on such a CD, depending on the extent to which the edges of the disc are trimmed.

Rice. 1.1. CD "business card".

The basis of a disk intended for recording information industrially is transparent polycarbonate, onto which a thin layer of aluminum alloy is applied, then covered with a protective layer of varnish and a printed image is applied (Fig. 1.2).

Rice. 1.2. CD structure.

DVD, DVD-R, DVD-RW, CD, CD-R, and CD-RW discs are manufactured by various companies: AMD, Amedia, Digitex, HP, Imation, MBI, Memorex, Philips, Smartbuy, Sony, TDK, Verbatim.

When purchasing CDs, you should pay attention to the following subtleties.

The presence of varnish stains on the edges of the disk can cause additional vibration and, as a result, errors when reading and writing data.

In the absence of additional layers of paint, the disc is translucent; you should not hope for a long service life of such a product.

If the disc is translucent, pay attention to how the reflective layer is applied. When viewed under light, the CD should be free of streaks and the reflective layer should be uniform over the entire surface.

The polycarbonate base must be homogeneous, without air bubbles.

Most CDs with games, movies or programs sold in stores are made by stamping.

Industrial DVD and CD recording occurs in eight stages.

1. Prepare the data that needs to be written to a CD.

2. A photosensitive photoresist layer of a certain thickness is applied to the surface of special polished glass processed with high precision in the form of a disk. Using a computer-controlled laser beam, certain areas of the photosensitive layer are illuminated.

3. After development in special solutions, small depressions called pits and convex areas called lands remain on the glass. The matrix, or stamper, obtained in this way is called Glass Master (glass base).

4. Using special reagents or vacuum deposition, a thin layer of nickel or silver is applied to Glass Master. This way we get Metal Master (master disk).

5. Create a negative of the master disc. In place of protrusions, depressions are formed, and vice versa, in place of depressions, protrusions are formed.

6. A stamp is created from a high-strength material, in the center of which a hole is drilled.

7. The stamp is placed in a press machine and copies are made.

8. An aluminum film is applied to the copies, designed to reflect the laser beam. The film thickness is hundredths of micrometers. The disc is varnished and a printed image is applied to it.

CD-R (CD Recordable) has a more complex structure. Another layer is added to its surface, onto which recording is made. The active, or recording, layer is located between the base and the reflective layer (Fig. 1.3).

Rice. 1.3. CD-R structure.

A blank CD-R, or “blank,” has a spiral track (Pre-groove), which contains special marks and synchronization signals. During recording, preliminary markings help the laser move along the desired path. In addition, CD burning programs themselves “read” some of the parameters of the CD-R being used, which makes it easier for the user to configure these programs. Synchronization signals are recorded at reduced amplitude and are subsequently overlapped by the recorded signal.

During recording, the laser beam moves along a spiral path and, at the moment of its activity, melts an additional layer. Under the influence of a laser, this layer changes its structure. This produces cells (pits) corresponding to the data written to the CD. After this stage, the structure of the active layer of the disk cannot be changed, and the data written to the disk cannot be deleted.

Note.
Pits are through holes in an additional layer.

The active layer is made from organic compounds: cyanine (Cyanine) and its derivative – phthalocyanine (Phtalocyanine). It is believed that phthalocyanine is more reliable and durable because it is less sensitive to sunlight. But discs with an active MetalAZO layer, developed by Mitsubishi Chemical, are even less sensitive to sunlight.

The requirements for the reflective layer of CD-Rs, compared to stamped discs, are quite high due to the presence of a recording layer. Therefore, more expensive materials are used to make the reflective layer - industrial gold and silver, as well as complex alloys.

The working surface of a CD-R, depending on the combination of substances used in the recording and reflective layers, can be of different colors. Previously, many discs had a golden working surface due to the use of gold.

Currently, silver is used to make the reflective layer, since this material is cheaper and has a higher reflectivity. Most often, the working surface is transparent, dark blue or light green. The service life of such disks, depending on the material of manufacture, ranges from 10 to 100 years.

CD-RW (Compact Disk Re-Writable - rewritable CD) (Fig. 1.4) - has, in addition to those described above, two more thermal protective layers. The presence of additional layers allows you to record on such a disc more than 1000 times.

Rice. 1.4. CD-RW structure.

During “burning” (writing a disc), the laser beam heats areas of the intermediate layer. With subsequent cooling, these areas transform from crystalline to amorphous. If information from a CD-RW needs to be erased, the laser beam heats the intermediate layer less intensely, and the amorphous areas crystallize.

DVD structure

Disc size – 80 mm (3.1 inches).

– DVD-1 (Single-sided, single-layer) – single-sided and single-layer disc. Can contain up to 1.36 GB of information (Fig. 1.5).

– DVD-2 (Single-sided, double-layer) – single-sided double-layer disc. Contains up to 2.48 GB of information (Fig. 1.6).

– DVD-3 (Double-sided, double-layer) – a two-layer disc with one information layer on each side. Capacity – up to 2.74 GB of information (Fig. 1.7).

– DVD-4 (Double-sided, double-layer) – a disc with two information layers on each side. The capacity of such a disk is up to 4.95 GB (Fig. 1.8).

Disc size – 120 mm (4.75 inches).

– DVD-5 (Single-sided, single-layer) – single-sided single-layer disc. Contains up to 4.7 GB of information.

Rice. 1.5. Structure of DVD-1 and DVD-5.

– DVD-9 (Single-sided, double-layer) – single-sided and double-layer disc. Capacity – up to 8.5 GB.

– DVD-10 (Double-sided, double-layer) – a two-layer disc with one information layer on each side. Contains up to 9.4 GB of information.

– DVD-18 (Double-sided, double-layer) – a two-layer disc with two information layers on each side. Capable of storing up to 17 GB of information.

Rice. 1.6. Structure of DVD-2 and DVD-9.

Rice. 1.7. Structure of DVD-3 and DVD-10.

Rice. 1.8. Structure of DVD-4 and DVD-18.

Note.
The number in the disc name—DVD-1, DVD-4, DVD-10, etc.—is a rounded capacity value.

Burning single-layer DVDs is similar to burning CDs, but burning dual-layer discs is significantly different from the process described earlier.

To obtain DVD-4 discs, you should glue two DVD-2, for DVD-18 - respectively, two DVD-9.

Note.
The AVIST material in the crystalline state has a 25–35% reflective ability, and upon transition to the amorphous state it darkens and does not reflect the laser beam.

DVD technology was originally developed for recording and playing movies. VideoDVD must provide the following capabilities:

Playback of films with a duration of at least 133 minutes;

Various options for displaying widescreen video;

Up to 32 subtitle options in various languages;

Surround sound;

Copy protection and regional coding;

Viewing interactivity.

Navigation data;

Reproduction objects.

Playback objects are divided into video, audio and graphics.

Zone 1 – USA and Canada.

Zone 2 – Western Europe, Japan, South Africa, Middle East.

Zone 3 – Southeast and East Asia, including Taiwan and Hong Kong.

Zone 4 – Latin America, South America, Caribbean Islands, Australia and New Zealand.

Zone 5 - countries of the former Soviet Union, Africa (except South Africa), India, Pakistan, Mongolia and North Korea.

Zone 6 - China.

Currently, DVD player manufacturers produce so-called "multi-zone" devices that support most formats.

Rules for using CDs

A CD is a rather complex device that requires proper handling and care.

Do not allow the work surface to become dirty. Hold the disc by the edges and do not touch the work surface with your hands. To remove any dust or fingerprints that may accidentally fall on the disc, use a soft, clean, dry cloth made from natural fabrics that does not have abrasive properties. The movements should not be strong; the disc should be wiped from its center to the edge. Do not use solvents to clean the work surface: acetone, gasoline, kerosene, etc.

Do not damage the work surface. Do not drop, scratch or bend the disc.

Store CDs in special plastic packaging at room temperature and do not expose their working surface to direct sunlight.

Do not write on the CD label with ballpoint pens, fountain pens, or hard pencils, as you may scratch the thin protective coating. Use soft pencils or felt-tip pens for this purpose, or make notes on the packaging in which the disc is stored.

To avoid shifting the center of gravity and increasing vibration when the CD rotates in the drive, do not attach additional labels to the disc.

CD/DVD drive

CD drives can be internal or external. They can be connected using a SCSI device, and this connection method is the most efficient, reliable and high-quality for the following reasons:

Allows you to work in the background while recording;

The drive does not conflict with other devices;

Less computer resources are used;

Does not require operating system optimization.

The disadvantages of this connection are the following:

Price;

The need to purchase an additional controller, to which you can connect from seven to fifteen different devices;

More complex installation.

External drives connected via FireWire or USB buses are much slower than internal IDE drives, but they can be connected and disconnected while the computer is running without turning off the computer itself or restarting the operating system.

Note.
USB 2.0 bandwidth – 480 Mbps. When installing a CD drive on Windows XP and Windows 2000 operating systems, no additional software is required. USB 2.0 allows you to connect up to 127 devices. The connected device is detected automatically. The software driver required for each peripheral device is enabled without user intervention.

In addition to the SCSI connector, internal models can be connected to IDE (ATAPI) connectors located on the motherboard using an 80-pin cable. The vast majority of CD burners use the IDE interface, as it is present in all modern computers. Most modern motherboards allow you to connect four IDE devices using two cables. DVD or CD drives are connected as one of the hard drives, and the BIOS independently recognizes the type of connected equipment. But if for some reason the BIOS does not detect one of the drives, then this problem can be resolved by using the BIOS Setup utility.

To access the BIOS CMOS Setup Utility, you must press the Delete key while your computer is booting. This should be done after loading the BIOS video, before loading Windows. If you're having trouble detecting when you press the Delete key, you can start pressing and releasing it as soon as you turn on the computer. If everything is done correctly, a blue screen with text in English will appear. Select Standard CMOS Features and press Enter.

Note.
To select the desired menu item, just move the red rectangle to the desired name and press the Enter key. You can move through the menu items left, up, down and right using the cursor keys: , ^ and v. To return or cancel an action, use the Esc key. If you press the Esc key several times (the number of presses depends on how deep you have gone into the BIOS), the Quit Without Saving (Y/N) dialog box will appear on the screen - this short phrase can be translated as “quit the program without saving the there are changes in it." This window provides an indispensable opportunity for a novice user to leave the program, leaving in it the parameters that were set before entering BIOS Setup.

In the menu that opens, we are interested in four parameters:

IDE Primary Master ;

IDE Primary Slave ;

IDE Secondary Master;

IDE Secondary Slave.

Note.
The names given in square brackets will correspond to the devices on your computer.

You can connect two cables to the motherboard, each of which connects two devices. For example, to the first connector of the first loop (Primary Master) you can connect one hard drive (in our case it is ), to the second connector of the first loop (Primary Slave) you can connect another hard drive or not connect anything (in this case, to this connector nothing is connected, that's why you see in square brackets ).

You can connect a CD drive to the first connector of the second cable, which is called Secondary Master (in this case it is). Another CD or DVD drive is connected to the second connector of the second cable, which is called Secondary Slave, or nothing is connected (in our case, this connector is occupied).

Sometimes, in order to save money, one cable is connected to the motherboard and a hard drive and CD drive are connected to it, but in any case, if you connect two devices to one cable, one device will be the Master and the second will be the Slave. ).

As a rule, the BIOS correctly determines the connection of devices, and you do not need to change anything in the settings yourself. If for some reason the system cannot detect a new device, you must independently indicate which connector it is connected to. This is done using the parameters Primary Master, Primary Slave, Secondary Master, Secondary Slave.

The most common mistake made by novice users is incorrectly setting the jumper on the device itself. A jumper is a small metal bracket that fits into the connectors that are located on the back of the CD or DVD drive. If two devices are connected to one loop, the position of the jumper must strictly delimit their levels: one device is Master, and the other is Slave.

Select the Advanced BIOS Features option and press Enter. In the menu that opens, pay attention to four parameters that characterize the sequence of checking devices. The BIOS does not always set this sequence correctly.

First Boot Device (the device from which the operating system will boot first) – . Choice available:

FloppyHDD-1USB-ZIP;

LS120 HDD-2USB-CDROM;

HDD-0HDD-3USB-HDD;

SCSIZIP100LAN;

CDROMUSB-FDDDisabled.

Second Boot Device (the device from which the operating system will be loaded secondarily) – . The same devices are available for selection as in the First Boot Device parameter.

Third Boot Device (the device from which the operating system will be loaded thirdly) – . The same devices are available for selection as in the First Boot Device parameter.

When checking the computer before loading the operating system, the BIOS alternately queries the CD drive, hard drive, and floppy drive in the exact order in which you specify. If the Windows XP operating system is installed on your computer, then the First Boot Device parameter should be set to CDROM. If the computer defaults to booting from the hard drive, it will freeze. In this case, it will be quite difficult to “cure” the operating system using a CD. Installation of Windows operating systems is automated, requiring the user only to set the BIOS settings so that the CD drive is detected before the hard drive. The BIOS will perform further actions completely independently; the user only needs to agree with all suggestions. The square brackets in the example above indicate Windows XP devices.

If your computer is running Windows 95 or 98, then the First Boot Device parameter should be set to Floppy (disk drive), since emergency booting in these operating systems is most often done from a floppy disk. The Second Boot Device parameter should be set to CDROM, otherwise the operating system will have to be installed using the command line, which does not always lead to the desired results. In the Third Boot Device parameter, select your hard drive.

Once you have configured the required settings, press F10. As a result, the Save & Exit Setup (Y/N) window will appear - this phrase can be translated as “exit the program, saving the settings made.” Press the Y key (Yes), and then Enter. The computer will continue to boot.

The quality of operation of a CD recording drive is significantly affected by the clock speed of the processor and the amount of RAM. It is not recommended to work in Windows 2000 or XP systems with less than 128 MB of RAM; in this case, errors will occur during recording, which will lead to damage to the workpieces. To avoid unwanted consequences, you should burn discs on low-performance computers by first disabling unused applications.

How CD drives work

The operation of the CD reader/writer is quite simple.

1. A laser diode emits a low-power beam of light with a length of 730–780 nm, which, passing through a guide prism and a beam splitter, hits a reflecting mirror.

Note.
During recording, the power of the laser beam increases significantly, and when erasing data it decreases.

2. Obeying the commands of the microprocessor, the carriage with the reflecting mirror moves to the desired track.

3. The laser beam is reflected from the disk, hits the mirror, then the beam splitter and then onto the guide prism.

4. From the prism, the beam enters the photo sensor, the photo sensor sends signals to the microprocessor built into the CD drive, where the data is processed and transmitted via a loop to the motherboard.

CD drives are produced by various companies: Yamaha, Plextor, Hitachi, HP, Sony, Ricoh, Philips, Panasonic, TEAC, AOpen, Mitsumi, etc. The cost of CD and DVD drives depends on the quality of the model, the level of the manufacturer, and functions and technical characteristics. As an example, let's look at the technical characteristics of some CD, DVD drives, as well as combo drives and their meanings.

CD-ROM Samsung SC/H152 (OEM).

– Speed formula – 52x.

– Buffer size – 128 KB.

– Data access time – 80 milliseconds.

– Supports formats: CD-ROM, Audio CD, Video CD, CD-i/FMW, CD-R, CD-RW, CD-Extra, Photo CD, Karaoke CD.

– Interface – IDE (ATAPI).

CD-ROM SONY CDU 415.

– Interface – SCSI.

– CD loading mechanism – tray.

– Supports formats: CD-DA, CD Extra, CD-ROM (Mode1), CD-ROM XA (Mode 2 Form 1 & 2), CD-I (Mode 2 Form 1 & 2), CD-I Ready, CD Bridge , Photo CD (single and multisession), Video CD.

– Buffer size – 0.25 MB.

– MTBF – 100 thousand hours.

– Dimensions – 14.6 x 4.1 x 20.3 cm.

Benq CB523B combo drive.

– Interface – E-IDE (ATAPI).

– CD loading mechanism – tray.

– CD/CD-R reading speed – up to 7800 KB/s (52x max CAV).

– DVD reading speed – up to 2100 KB/s (16x max CAV).

– Supports formats: CD-I, CD-ROM, Audio CD, Video CD, CD-R, CD-RW, Photo CD, Karaoke CD, Text CD, Enhanced CD, Bootable CD, Data CD, DVD-ROM, DVD- R, DVD-RW, DVD+R DVD+RW.

– Recording formats – TAO (Track at Once), DAO (Dick at Once), SAO (Session at Once), Multi-Session, Packet Writing, UDF.

– Data access time CD -120 milliseconds, DVD – 140 milliseconds.

– Data buffer size is 2048 KB, Seamless Link buffer underrun error prevention technology is used.

– Supported disc sizes are 8 and 12 cm in diameter.

– MTBF – 125 thousand hours.

– Dimensions – 146 x 42 x 198 cm.

Writemaster TS-H552.

– Interface – IDE (ATAPI).

– CD loading mechanism – tray.

– CD-RW reading speed – 32x max.

– DVD reading speed -16x max.

– Reading speed DVD-R, DVD+R DVD-RW, CD-RW, DVD+R DL – 16x max.

– CD-R writing speed – 40x max.

– CD-RW recording speed – 32x max.

– DVD+RW recording speed – 4x max.

– DVD-RW recording speed – 4x max

– DVD+R recording speed – 16x max.

– DVD-R recording speed – 12x max.

– DVD+R DL recording speed – 2.4x max.

– Supports CD formats – CD-ROM, CD-ROM XA, CD-DA, Video CD, Photo CD, Text CD, CD-R, CD-RW.

– Supports DVD formats – DVD-ROM (Single/dual layer), Video DVD, DVD-ROM, DVD-R, DVD-RW, DVD+R, DVD+R DL, DVD+RW.

– Data access time: CD – 110 milliseconds, DVD – 130 milliseconds.

– Supported disc sizes are 8 and 12 cm in diameter.

– Dimensions – 148.2 x 42 x 184 mm.

– Interface – IDE (ATAPI, UDMA/33).

– CD loading mechanism – tray.

– CD/CD-R reading speed – 48x max.

– DVD reading speed – 16x max.

– CD-R writing speed – 24x max.

– CD-RW writing speed – 6x max.

– DVD+RW recording speed – 8x max.

– DVD+R/DVD-R recording speed – 16x max.

– DVD+R/-R DL recording speed – 4x max.

– Supports CD formats – CD-DA, CD-ROM, CD-ROM/XA, Photo CD, Video CD, CD Extra, Text CD, Bridge CD.

– Supports DVD formats – DVD single/dual layer, DVD-R/+R, DVD-RW/+RW, DVD+R9/-R9.

– Recording formats – TAO with Zero gap, DAO (Dick at Once), SAO (Session at Once), Multi-Session, Fixed and Variable Packet.

– Data access time: CD – 120 milliseconds, DVD – 140 milliseconds.

– Data buffer size – 2 MB.

– Supported disc sizes are 8 and 12 cm in diameter.

– Dimensions – 148 x 42 x 190 mm.

ASUS CRW-5232AS-U. External CD drive.

– Interface – USB 2.0 (USB 1.1).

– CD loading mechanism – tray.

– CD-ROM reading speed – up to 7800 KB/s (52x max CAV).

– CD-R recording speed – up to 7800 KB/s (52x max P-CAV).

– CD-RW recording speed – up to 4800 KB/s (32x max P-CAV).

– Audio track digitization speed – 52x max.

– Supports formats: Audio CD, CD-ROM, CD-ROM/XA, Photo CD, CD Extra, Video CD, Text CD, Karaoke CD, I-Trax.

– Data buffer size – 2 MB.

– Supported disc sizes are 8 and 12 cm in diameter.

– Installation method – vertical and horizontal.

– Dimensions – 156 x 50 x 226 mm.

CD drive options

Let's look at the parameters that affect the quality of the CD drive.

Speed formula for CD. CDs were originally developed for recording and storing music, and the data read speed was 153,600 bytes/s. With the advent of CD drives designed for computer data, the speed increased, but still remained a multiple of 153,600 bytes/s. Subsequently, the speed of reading information from disks increased, but at the same time remained a multiple of this initial value. Based on this, you can calculate the speeds inherent in modern drives: if your drive has a read speed of 52x, then multiplying 52 by 153,600 bytes/s, we get 7,987,200 bytes/s. If the write speed of your drive is 24x, then this is 24 x 52 = 3,686,400 bytes/s.

Note.
Often, for ease of calculation, the speed of the first CD drive is assumed to be 150 KB/s, rather than 153,600 bytes/s.

In a similar way, let's try to calculate the data reading speed for DVD drives. For the first speed in this case, you should take nine CD speeds. Therefore, 153,600 x 9 = 1,382,400 bytes/s, or, in round numbers, 1385 KB/s. Accordingly, the data reading speed for DVD 16x is 16x1382,400 = 22,118,400 bytes/s. Using these simple mathematical calculations, you can calculate the data flow at any speed.

The CD loading mechanism can be of several types.

– Tray – tray. Pull-out CD loading mechanism.

– Caddy is an assistant. First, the disc is inserted into a special box, and then this box is inserted into the drive receiving device. This mechanism for loading CDs is more reliable, but less convenient.

– Slot-in – can be roughly translated as “entrance slot”. The disc is directly inserted into the drive slot. Loading a CD this way is similar to loading a regular floppy disk.

Buffer size.

During recording, data of all types must be continuously fed to the recording device; if this process is interrupted, the workpiece will be damaged. To ensure error-free operation, all modern drives have a special set of chips where information intended for recording is placed in advance. This is the buffer. There are three types of buffers.

– Static buffer – stores in memory all information entering the CD drive.

– Dynamic buffer – increases the transfer speed of fragmented data and small files.

– Read-ahead buffer – data is buffered in advance and transferred to the recording device as needed. The computer seems to predict which file will be needed for recording.

The larger the buffer size, the better and more reliable the CD drive.

Data access time. This is the delay between receiving a command to read data and actually reading the data. This parameter significantly affects the recording of highly fragmented files, as well as a large number of small data located on different parts of the hard drive.

The drive data sheet indicates the average data access time. On internal tracks the delay will be greater, and on external tracks it will be less than specified in the characteristics. The faster the data access time, the faster the CD drive is.

CD drives can support the following CD formats.

– Audio CD, or CD-DA. Red Book is a format developed for recording music CDs. After recording, such a disc can be listened to on a household CD player.

– CD-ROM. Yellow Book is a format designed for recording and storing computer data. Such CDs are produced using special equipment using the stamping method.

– Video CD – format for recording and storing video data.

– CD-R – the CD drive can play and burn one-time discs.

– CD-RW – the drive plays and writes discs for reusable use.

– CD Extra – the CD drive allows you to create discs that can contain both audio data and computer data.

– Photo CD is a format developed by Kodak. Used to record collections of photographs.

The DVD formats that CD drives can handle are as follows.

– DVD-ROM – a disc recorded industrially using the stamping method.

– DVD-R – DVD-Recordable – a recordable disc that differs from a factory DVD-ROM by the presence of a special pigment layer between the transparent substrate and the reflective surface. Holes (pits) in such a layer are not stamped, but burned out with a high-power laser beam.

– DVD+R – similar to DVD-R format. The DVD+R and DVD-R formats are similar to each other, their technical characteristics are the same. The only difference between these formats is that different organic substances are used as dyes. The presence of such similar formats is caused by competition among manufacturing companies.

– DVD-RW – rewritable discs. The format was developed by Pioneer.

– DVD+RW – analogue of the DVD-RW format. Developed by Sony and Philips.

MTBF. This is the period during which your CD drive must operate smoothly according to the MTBF standard. After this time, the drive parts will exhaust their service life, and the manufacturer cannot guarantee that the product will continue to work correctly and efficiently. The more time a CD drive can operate, the better; it cannot operate indefinitely.

The main enemies of high-quality drive operation are vibration and heat. After stamping, the disk profile is usually a curved line with two characteristic bends, and only the central part corresponds to the norm. Even very expensive discs are not without this drawback. To extend the life of your CD drive, you must use it properly.

– Try not to create a large number of copies of CDs in a row. Household recording drives become very hot during recording, which can lead to premature wear of the mechanism. It is recommended to make a maximum of two or three copies in a row, then let the drive rest for half an hour, after which you can make two or three more copies, etc. During the break, it is better to disconnect the computer from the network.

– Do not use CDs that are severely warped or scratched. Remember: the cost of a CD drive is significantly higher than the cost of the disc.

– If the CD drive is very dirty, the drive itself may scratch the discs. In this case, the scratches are located around the circumference.

To prevent severe contamination of drives, it is necessary to use the PMC Clean program.

Buy a drive cleaning CD from the store. On the working side of such a disk there is a small brush. Apply one drop of the special liquid included in the kit to the brush, insert the CD into the drive. Select Start > My Computer. Double-click on the drive icon to open the contents of the cleaning disc. Find the PMC Clean launcher icon and double-click to launch it. Select the language in which commands will be displayed. In the window that appears, press the START button, after which the music will play and cleaning the drive will begin (Fig. 1.9). Upon completion of cleaning, press the TEST button to start the test program. After reviewing the results, you can exit the drive cleaning program by pressing the END button.

The second way to work with PMC Clean is to install the program on your hard drive and launch it using a shortcut that can be placed on the Desktop. As you understand, the cleaning disk will still have to be inserted into the drive. After installing the program, you can configure it to launch automatically. In this case, for example, a week after cleaning the drive, a window will appear on your computer screen after loading the operating system reminding you of the need to carry out maintenance work.

Rice. 1.9. Cleaning the CD drive.

Attention!
Run the CD drive cleaning program only when necessary. Excessive zeal in this case can only cause harm.

Another way to extend the life of your CD drive is to install programs that allow you to create virtual CD drives and virtual CDs.

Ministry of Education of the Russian Federation

Irkutsk State Technical University

Department of AS

Course work

“CDs. Classification. Reading and writing principles»

Completed: art. gr. ASU-99-1

Belyaev V. A.

Accepted by: Bakhvalov S.V.

Irkutsk, 2002

General information about CDs………………3

CD format……………………………4

Classification………………………………….5

Principle of CD-R recording…………………………….6

CD-RW recording principle………………………….7

Recording methods…………………………………8

Literature……………………………………………………11

In 1982, Sony and Philips completed work on the CD audio format (Compact Disk), thereby ushering in the era of digital media on compact discs. The operating principle of these discs is optical. Reading and writing is carried out by a laser. In a CD, data is encoded and recorded as a sequence of reflective and non-reflective sections. The reflection is interpreted as one, the “valley” as zero. I will give some technical parameters of CDs. The operating wavelength of the laser is 780 nm. CD diameter 120 mm. Disc thickness 1.2 mm. Disc capacity 680 MB (74 min audio). Weight 14-33 g. The chain of pits is arranged in a spiral, like in a gramophone record, but away from the center (in fact, a CD is a sequential access device with fast rewinding). The interval between turns is 1.6 µm, pit width is 0.5 µm, depth is 0.125 µm (1/4 wavelength of the laser beam in polycarbonate), minimum length is 0.83 µm (Fig. 1).

Rice. 1. CD surface.

There are modifications of 80 minutes (700 MB), 90 minutes (791 MB) and 99 minutes (870 MB). Nominal (1x) data transfer rate is 150 KB/sec (176400 bytes/sec audio or “raw” data, 4.3 Mbit/sec “physical” data). While all magnetic disks rotate at a constant number of revolutions per minute, that is, with a constant angular velocity (CAV, Constant Angular Velocity), a compact disk usually rotates at a variable angular velocity to provide a constant linear speed when reading (CLV, Constant Linear Velocity). Thus, reading the internal sides is carried out with an increased number of revolutions, and the external ones - with a reduced number of revolutions. This is what determines the rather low data access speed for CDs compared, for example, with hard drives.

Consider the CD format.

The surface of the disk is divided into areas:

PCA (Power Calibration Area). Used to adjust the laser power of the recording device. 100 elements.

PMA (Program Memory Area). The coordinates of the beginning and end of each track are temporarily recorded here when the disc is removed from the recording device without closing the session. 100 elements.

Lead-in Area - a 4 mm wide ring (diameter 46-50 mm) closer to the center of the disk (up to 4500 sectors, 1 minute, 9 MB). Consists of 1 track (Lead-in Track). Contains TOC (absolute temporary addresses of tracks and the beginning of the output area, accuracy - 1 second).

Data area (program area, user data area).

Lead-out area - ring 116-117 mm (6750 sectors, 1.5 minutes, 13.5 MB). Consists of 1 track (Lead-out Track).

Each byte of data (8 bits) is encoded into a 14-bit character on the medium (EFM encoding). Characters are separated by 3-bit spaces, chosen so that there are no more than 10 consecutive zeros on the medium.

From 24 bytes of data (192 bits) a frame (F1-frame) is formed, 588 bits of media, not counting the spaces:

synchronization (24 bit media)

subcode symbol (bits of subchannels P, Q, R, S, T, U, V, W)

12 data characters

4 character verification code

12 data characters

4 character verification code

Decoding may use different strategies for detecting and correcting group errors (probability of detection vs. reliability of correction).

A sequence of 98 frames forms a sector (2352 information bytes). The frames in the sector are shuffled to reduce the impact of media defects. Sector addressing originates from audio discs and is written in A-Time format - mm:ss:ff (minutes:seconds:beats, fractions per second from 0 to 74). The countdown starts from the beginning of the program area, i.e. the sector addresses of the input area are negative. The subchannel bits are assembled into 98-bit words for each subchannel (of which 2 bits are synchronization). Subchannels used:

P - marking the end of the track (min 150 sectors) and the beginning of the next (min 150 sectors).

Q - additional information about the contents of the track:

number of channels
data or sound
is it possible to copy
a sign of frequency pre-emphasis: artificial increase in high frequencies by 20 dB
subchannel usage mode
- q-Mode 1: The input area stores the TOC here, the program area stores track numbers, addresses, indexes and pauses
  q-Mode 2: disk catalog number (same as on the barcode) - 13 digits in BCD format (MCN, ENA/UPC EAN)
  q-Mode 3: ISRC (International Standard Recording Code) - country code, owner, year and serial number of the recording

A sequence of sectors of the same format is combined into a track (track) from 300 sectors (4 seconds, see subchannel P) to the entire disc. A disc can have up to 99 tracks (numbered 1 to 99). A track may contain service areas:

pause - only subchannel information, no user data

pre-gap - the beginning of the track, does not contain user data and consists of two intervals: the first, at least 1 second long (75 sectors), allows you to “build up” from the previous track, the second, at least 2 seconds long, sets the format of the track sectors

post-gap - end of track, does not contain user data, at least 2 seconds long

The lead-in digital area must end with a post-gap. The first digital track must start from the second part of the pre-gap. The last digital track must end with a post-gap. The output digital area does not contain pre-gap.

There are many standards and formats for CDs, depending on the purpose and manufacturers. I will give as an example not all existing ones: Audio CD (CD-DA), CD-ROM (ISO 9660, mode 1 & mode 2), Mixed-mode CD, CD-ROM XA (CD-ROM eXtended Architecture, mode 2, form 1 & form 2), Video CD, CD-I (CD-Interactive), CD-I-Ready, CD-Bridge, Photo CD (single & multi-session), Karaoke CD, CD-G, CD-Extra, I -Trax, Enhanced CD (CD Plus), Multi-session CD, CD-Text, CD-WO (Write-Once). A full description of them would take too much space, and this is not the purpose of writing this work.

Depending on the number of possible recording operations, CDs are divided into: CD-ROM (read only memory), CD-R (recordable), also known as CD-WORM (write once read many), CD-RW (rewritable). Accordingly, the CD-ROM is manufactured at the factory, and further recording on it is impossible; CD-R is intended to be written once at home; CD-RW allows many write operations. CD-ROM discs are polycarbonate, coated on one side with a reflective layer (aluminum or - for critical applications - gold) and a protective varnish on the other. The reflectivity is changed by stamping recesses in the metal layer. At the factory they are simply stamped from the matrix. This is not very interesting for us, and we will dwell in more detail on discs that can be recorded on a home computer.

Let's start with write-once discs (CD-Rs).

In terms of its internal structure, a CD-R disc resembles a layer cake, the “filling” of which consists of active, reflective and protective layers, which are successively applied to a polycarbonate base.
At the same time, the basis of a CD-R disc is no different from that used in the technology of manufacturing compact discs by casting: the characteristics of the plastic must be such that the laser beam passing through it is properly focused and does not cause destruction of the disc. An active (or recording) layer is applied to the base, on which, in fact, information is recorded. During recording, a powerful laser beam heats small areas of the active layer. Under the influence of high temperature, the properties of the substance of the recording layer in the place of heating change, as a result, it ceases to transmit light. In other places that were not heated by the laser, light still passes through the recording layer unhindered. Cyanine and phthalocyanine are commonly used as materials for the recording layer.

All that remains is to deal with the reflective layer. So, the reflective layer is the thinnest plate of gold or silver. Moreover, silver is better because it has a higher reflection coefficient. But, nevertheless, discs with a gold reflective layer continue to be produced, although they are worse and much more expensive. As usual, you have to sacrifice one quality for the sake of another: gold is a very durable material, and silver oxidizes over time. Therefore, in cases where long-term data storage is required, disks with a gold reflective layer are used. Well, the last layer, protective, is applied on top of the reflective one and serves to mechanically protect the CD-R disc and apply a label to it. Here, too, options are possible: in the simplest case, the protective layer is a varnish coating. Not the best protection option. The varnish can peel off, and, even worse, there may be a chemical reaction between the varnish and various substances that come into contact with it (for example, with the ink you use to write on the back of the disc). However, recently some manufacturers of CD-R discs have been using special resistant varnishes to coat discs, which gives them additional reliability. More reliable protective coatings are an additional layer of special plastic. In addition to protection, this method also makes the appearance of the disc more attractive compared to varnish.

It is impossible to restore the transparency of substances used as the active layer in CD-R discs. On the one hand, this provides some guarantee that the recorded information will be securely stored. Indeed, there is only one way to damage the recording applied to the active layer - to make the transparent areas opaque. This is what can happen under the influence of, for example, bright sunlight. On the other hand, it is impossible to rewrite a disc once written. Unfortunately, it has not yet been possible to resolve this contradiction. Today we are forced to choose between the possibility of rewriting and the reliability of information storage.

And if we choose to rewrite, we will have to use a CD-RW disc. The only difference between such discs and CD-Rs is the design of the recording layer. For CD-R discs, recording is based on changes in the optical properties of the layer under the influence of temperature - when heated, the layer becomes cloudy. The principle of recording CD-RW discs is a little more complicated; it uses the phenomenon of phase transition. The intermediate layer of special organic material can be either amorphous or crystalline.

An amorphous substance, as is known from a physics course, is a substance that, when heated, does not turn into a liquid, but gradually softens and becomes more and more fluid. An example of such a substance would be the well-known plasticine. Or honey. By the way, the example of honey clearly shows the general property of amorphous substances - over time they turn into a crystalline form. Place a jar of transparent fresh honey in the cupboard and do not touch it for 2 years. Then take it out, and you will see that the honey has thickened, or even become hard, “candied.” And it became opaque! This is the principle on which CD-RW recording is based. The transparency of the CD-RW recording layer depends on the state in which the substance is, amorphous or crystalline. And we can control the process of transition from one state to another. If the recording layer is heated to a sufficiently high temperature and then cooled sharply, the substance becomes amorphous. This is exactly how the recording process works. On a blank CD-RW disc, the recording layer is in crystalline form. A powerful beam from a recording laser heats up a section of the surface and turns off, the disk quickly cools down and at this point part of the active layer turns into an amorphous form. In order to return the substance of the active layer to the crystalline state, it is heated again, but to a lower temperature (with a less intense beam). And the substance returns to the crystalline state. This operation can be performed about 1000 times, which is how many rewrite cycles CD-RW discs can withstand.

And everything would be fine if it were not for the very peculiarity of amorphous substances to crystallize over time. No matter how we store a CD-RW, after a few years the recording will be irretrievably lost. In addition, such discs can easily be erased by simple heating. But you can re-record.

Another feature of CD-RW discs appears when reading. If in CD and CD-R discs we clearly distinguished two types of surface areas - light reflecting and non-reflecting, then in CD-RW the entire surface is reflective, although to varying degrees. Therefore, when reading a CD-RW disc, information is read at the moment when the laser beam hits the transition area between crystalline and amorphous matter. The laser used in this entire process is standard, with a wavelength of 780 nanometers. Reading is also done with a standard laser, but the difference in signal levels is less for CD-RW discs than for CD-ROMs.

Rice. 2. Structure of CD, CD-R, CD-RW discs

Let's look at ways to burn CDs at home. To do this, you need not only a CD burner, but also special software. They are usually supplied together. Examples of such programs are Easy CD, CD Creator, CD Publisher. The Windows XP operating system has built-in support for burning CDs.

The process of recording one session is a single operation that cannot be interrupted, otherwise the disc will be damaged. To ensure uniform flow of recorded information to the laser, all drives have a buffer, the exhaustion of data in which (Underrun) leads to an emergency interruption of recording. Exhaustion of data in the buffer can be caused by the launch of parallel processes, the operation of the virtual memory system (swapping), hijacking of the processor by “rogue” device drivers, or freezing of the program or operating system. Mechanical shocks from the drive also cause recording failure.

There are two main CD-R recording modes: DAO (Disk At Once - the entire disc at one time) and TAO (Track At Once - one track (session) at one time). When recording using the TAO method, the laser is turned on at the beginning of each track and turned off at the end; At the points where the laser is turned on and off, a series of special frames are formed - run-in, run-out and link, designed to link the tracks together. A standard interval contains 150 such frames (2 seconds). When recording using the DAO method, the laser is turned on throughout the recording of the entire disc.

A disc written in one go is the most universal and can be read by any CD-ROM with any file manager, however, after writing, it is impossible to add new data to the disc, and the DAO mode is not supported by all recording drives. This mode is also desirable for recording master discs for subsequent duplication by stamping - most standard machines for making matrixes accept only continuously recorded originals.

In TAO mode, multi-session discs are written that allow subsequent data recording; in this case, only the Lead In zone (open session) is recorded for the session. When recording each subsequent session, the previous one is closed by recording the Lead Out zone followed by the Lead In of the new session. These two zones consume an additional 13.5 MB (6750 frames) of disk space.

According to the standard, in order to be read normally in all devices, the disk must be Closed by writing the output zone. Closing the disk increases the likelihood of it being successfully read in other drives (the vast majority of modern drives do not pay attention to whether the disk is closed), but makes it impossible to add additional sessions.

Before you start recording, you need to create a complete list of files included in the session; Subsequent addition of files to the disk is possible only in the form of additional sessions. CD-ROM drives that do not support multi-session recording read only the first TOC from the disk - accordingly, they can only read files from the first session. Multi-session CD-ROMs only read the latest TOC, so the last TOC on a multi-session disc must also contain references to files from previous sessions. To do this, when recording the next session, use the option of importing sessions (Import Track) to create a complete overall TOC. Directories with the same names are merged, as when appending to a regular disk. In any case, files are addressed within the entire disk, so only TOCs are merged. Session files that were not imported when creating the next one will not be present in the resulting directory and normal access to them will be impossible, however, many CD-R burning programs allow you to selectively read individual disc sessions. If recording to a one-time multi-session disk is interrupted for some reason, in some cases it is possible to use the remaining free disk space. This requires a recording program that has an option to close a session (Close Track/Session), after which the necessary data is recorded in the next session without importing the interrupted session (preceding sessions can be imported).

Because the final visibility of each file is determined by the TOC import process, it is possible to exclude individual files from the catalog and selectively replace files with matching names. The old copy of the file continues to remain on disk in one of the previous sessions, but a link to the new copy is placed in the new directory. Selectively excluding files from previous sessions into the new session's directory has the effect of "deleting" them. The visibility of files "deleted" in this way can later be "restored" by importing them into new sessions.

To record CD-RWs, they can be pre-formatted - divided into sectors, like magnetic disks. After formatting, a CD-RW disk can be used like a regular removable disk - standard file operations of copying, deleting and renaming are converted by the CD-RW drive driver into a series of disk sector rewrite operations. Thanks to this, no special software is required to work with CD-RW discs, except for a drive driver with UDF support and an initial partitioning program.

Some versions of burning software allow you to burn bootable discs. The bootable part of the CD-ROM is recorded as an image of a boot floppy disk or hard drive, from which the A: drive is emulated when the motherboard BIOS boots.

Literature

people.kstu.edu/CSN/CDR/rab.htm

kstu.kz/~yas/theory_lw/opt_70.htm

bog.pp/hard/cdrom.html

Similar abstracts:

The presence of an active (registering) layer in a CD-R disc (blank for recording). Exact values for the width, depth and angle of the side walls. Required laser power when recording. Types of dyes, reflective, protective and decorative layers of the CD.

In the first hard models, a material based on iron oxide was used as a magnetic coating. Now manufacturers use chromium oxide, which has greater wear resistance.

How a CD-ROM drive works The operating principle of a CD-ROM drive is similar to that of conventional floppy disk drives. The surface of the optical disk (CD-ROM) moves relative to the laser head at a constant linear speed, and the angular speed varies depending on the radial position...

Despite the wide variety of hard drive models, their operating principles and basic structural elements are the same. Figure 5 shows the main design elements of a hard disk drive:

· magnetic disks;

· read/write heads;

· head drive mechanism;

· disk drive motor;

· printed circuit board with electronic control circuit.

A typical drive consists of a sealed housing (hermoblock) and an electronic unit board. The HDA contains all the mechanical parts, and the board contains all the control electronics. A spindle with one or more magnetic disks is installed inside the HDA. The engine is located underneath them. Closer to the connectors, on the left or right side of the spindle, there is a rotary magnetic head positioner. The positioner is connected to the printed circuit board by a flexible ribbon cable (sometimes solid wires).

The hermetic block is filled with air under pressure of one atmosphere. In the covers of the hermetic blocks of some hard drives there is a special hole, sealed with a filter film, which serves to equalize the pressure inside and outside the block, as well as to absorb dust.

Figure 5 - Basic design elements of a hard drive drive

The overall dimensions of hard drives are standardized according to a parameter called form factor (Form-Factor). For example, all HDDs with a 3.5" form factor have standard case dimensions of 41.6x101x146 mm.

Magnetic disk substrates The first hard drives were made of aluminum alloy with the addition of magnesium. Modern models use a composite material of glass and ceramics with a low thermal expansion coefficient as the main material for disk plates, which makes them less susceptible to temperature changes and more durable. Magnetic disks are available in the following sizes: 3.5"; 5.25"; 2.5"; 1.8".

The discs are covered with a magnetic substance - the working layer. It can be either oxide or thin film based.

Read/write heads provided for each side of the disc. When the drive is turned off, the heads touch the disk. When the disks unwind, the aerodynamic air pressure on the heads increases, which leads to their separation from the working surfaces of the disks. The closer the head is to the disk surface, the higher the amplitude of the reproduced signal.

Head drive mechanism ensures the movement of the heads from the center of the disks to the edges and actually determines the reliability of the drive, its temperature stability and vibration resistance. All existing head drive mechanisms are divided into two main types: with a stepper motor and a moving coil.

Drive motor causes the disk pack to rotate, the speed of which, depending on the model, is in the range of 3600 - 7200 rpm (i.e. the heads move at a relative speed of 60 - 80 km/h). The rotation speed of some hard drives reaches 15,000 rpm. The hard drive rotates continuously even when it is not being accessed, so the hard drive should only be installed vertically or horizontally.

Printed circuit board with electronic circuit controls and other drive components (front panel, configuration elements and mounting parts) are removable. Electronic circuits for controlling the motor and head drive and a circuit for exchanging data with the controller are mounted on the printed circuit board. Sometimes the controller is installed directly on this board.

Questions for self-control:

1. Floppy drives. Design, principle of operation, main components, technical characteristics of FDD;

2. Logical structure of floppy disks;

3. Hard disk drives. Design and operating principle of HDD, form factors, types;

4. Main characteristics and operating modes of hard disk drives. Controllers and HDD connection;

5. Modern storage models;

6. Logical structure of the hard drive;

7. Formatting hard drives;

8. Hard disk maintenance utilities.

Topic 4.2 CD-R (RW) drives. DVD-R (RW)

The student must:

have an idea:

· about the purpose of CD-R (RW) drives. DVD-R (RW)

know:

· operating principle and main components of a CD-ROM drive;

· CD-ROM drive performance characteristics;

· operating principle and main components of a DVD drive;

be able to:

· connect CD and DVD drives;

CD-R, (RW), DVD-R (RW) drives: operating principle, design and main components, technical characteristics.

Guidelines

CD-ROM drives

CD-ROM is a compact disc (CD) designed to digitally store information previously recorded on it and read it using a special device called a CD-ROM driver - a drive for reading CDs.

The CD manufacturing process includes several stages.

At the first stage, an information file is created for subsequent recording on the medium. At the second stage, using a laser beam, information is recorded onto a medium, which is a fiberglass disk coated with a photoresist material. Information is recorded in the form of a sequence of spirally arranged indentations (strokes), as shown in Figure 6. The depth of each pit stroke (pit) is 0.12 µm, the width (in the direction perpendicular to the plane of the drawing) is 0.8 - 3.0 µm. They are arranged along a helical track with a spacing of 1.6 µm between adjacent turns, corresponding to a density of 16,000 TPI (625 TPI). The length of the streaks along the recording track ranges from 0.83 to 3.1 µm.

Figure 6 - Geometric characteristics of a compact disc (a) and its cross section (b)

At the next stage, the photoresist layer is developed and the disk is metallized. A disc made using this technology is called a master disc. To replicate CDs, several working copies are made from the master disc using electroplating. Working copies are coated with a more durable metal layer (for example, nickel) than the master disk, and can be used as matrices for duplicating CDs up to 10 thousand pieces. from each matrix. Replication is carried out by hot stamping, after which the information side of the disc base, made of polycarbonate, is vacuum metallized with a layer of aluminum and the disc is coated with a layer of varnish. Disks made by hot stamping, in accordance with the passport data, provide up to 10,000 cycles of error-free data reading. The thickness of the CD is 1.2 mm, diameter - 120 mm.

The CD-ROM drive contains the following main functional units:

· boot device;

· optical-mechanical unit;

· drive control and automatic control systems;

· universal decoder and interface unit.

Figure 7 shows the design of the optical-mechanical unit of the CD-ROM drive, which works as follows. An electromechanical drive rotates a disk placed in the loading device. The optical-mechanical unit ensures that the optical-mechanical reading head moves along the disk radius and reads information. A semiconductor laser generates a low-power infrared beam (typical wavelength 780 nm, radiation power 0.2 - 5.0 mW), which hits a separation prism, is reflected from a mirror and focused by a lens on the surface of the disk. The servo motor, following commands from the built-in microprocessor, moves a movable carriage with a reflective mirror to the desired track on the CD. The beam reflected from the disk is focused by a lens located under the disk, reflected from the mirror and hits a separation prism, which directs the beam to a second focusing lens. Next, the beam hits a photosensor, which converts light energy into electrical impulses. Signals from the photosensor are sent to a universal decoder.

Figure 9 - Design of the optical-mechanical CD-ROM drive unit

Automatic tracking systems for the disk surface and data recording tracks ensure high accuracy of information reading. The signal from the photosensor in the form of a sequence of pulses enters the amplifier of the automatic control system, where tracking error signals are isolated. These signals enter automatic control systems: focus, radial feed, laser radiation power, linear speed of disk rotation.

A universal decoder is a processor for processing signals read from a CD. It consists of two decoders, a random access memory device and a decoder control controller. The use of double decoding makes it possible to recover lost information up to 500 bytes. The random access memory serves as a buffer memory, and the controller controls the error correction modes.

The interface unit consists of a digital-to-analog converter, a low-pass filter and an interface for communication with a computer. When playing audio information, the DAC converts the encoded information into an analog signal, which is sent to an amplifier with an active low-pass filter and then to a sound card that is connected to headphones or speakers.

The following are performance characteristics that you should consider when selecting a CD-ROM for your specific application.

Data Transfer Rate (DTK) - The maximum speed at which data is transferred from the storage medium to the computer's RAM. The high data transfer speed of a CD-ROM drive is necessary primarily for synchronizing picture and sound. If the transmission speed is insufficient, video frames may be dropped and audio may be distorted.

Reading quality is characterized by the error rate (Eror Rate) and represents the probability of receiving a distorted information bit when reading it.

Average Access Time (AT) is the time (in milliseconds) it takes the drive to find the data it needs on the media.

Buffer capacity is the amount of random access memory in a CD-ROM drive used to increase the speed of access to data recorded on the media. Buffer memory (cache memory) is a memory chip installed on the drive board for storing read data.

Mean time between failures is the average time in hours that characterizes the failure-free operation of a CD-ROM drive.

In the process of development of optical disk drives, a number of basic formats for recording information on CDs have been developed.

CD-DA (Digital Audio) format - digital audio compact disc with a playing time of 74 minutes.

The ISO 9660 format is the most common standard for the logical organization of data.

The High Sierra (HSG) format was proposed in 1995. and allows data written to disk in ISO 9660 format to be read by all types of drives, which has led to widespread replication of programs on CD and contributed to the creation of CDs targeting various operating systems.

The Photo-CD format was developed in 1990-1992. and is intended for recording on CD, storing and playing static video information in the form of high-quality photographic images. A Photo-CD format disc holds from 100 to 800 photographic images of the corresponding resolutions - 2048 x 3072 and 256 x 384, and also stores audio information.

Any CD-ROM disc containing text and graphic data, audio or video information is classified as multimedia. Multimedia CDs exist in various formats for various operating systems: DOS, Windows, OS/2, UNIX, Macintosh.

The CD-I (Jntractive) format was developed for a wide range of users as a standard multimedia disc containing various text, graphic, audio and video information. A CD-I format disc allows you to store a video image with sound (stereo) and a playback duration of up to 20 minutes.

The CD-DV (Digital Video) format provides recording and storage of high-quality video with stereo sound for 74 minutes. During storage, compression is provided using the MPEG-1 (Motion Picture Expert Group) method.

Reading the disc is possible using a hardware or software MPEG decoder.

The 3DO format was developed for game consoles.

CD-ROM drives can operate with either a standard IDE (E-IDE) interface or a high-speed SCSI interface.

The most popular CD-ROM drives in Russia are products with the brands Panasonic, Craetive, Samsung, Pioneer, Hitachi, Teac, LG.

DVD drives

Solving the problem of increasing the capacity of optical storage media based on improving the production technology of CDs and drives, as well as existing scientific and technical solutions in the field of high-quality digital video, led to the creation of CDs with increased capacity.

The image quality stored in DVD format is comparable to the quality of professional studio video recordings, and the sound quality is also not inferior to studio quality. Audio information in DVD format is read at a speed of 384 KB/s, which makes it possible to organize multi-channel audio.

Such capabilities of DVD format discs are due to the improved parameters of the working surface of the discs. Like CDs, DVDs have a diameter of 120 mm. The DVD drive uses a semiconductor laser with a visible wavelength of 0.63 - 0.65 microns. This reduction in wavelength (compared to 0.78 microns for a conventional CD drive) made it possible to reduce the size of recording lines (pits) by almost half, and the distance between recording tracks - from 1.6 to 0.74 microns. The pits are arranged in a spiral, like on vinyl long-playing records.

DVD-ROM drives come with both a hardware MPEG-2 decoder in the form of an expansion card for the PCI bus, and a software decoder. DVD-R recording and DVD-RW rewriting drives are capable of working with single-layer, single-sided discs with a capacity of up to 4.7 - 5.2 GB at an information writing speed of about 1 MB/s.

Questions for self-control:

1. CD-R, (RW) drives, operating principle, design and main components, technical characteristics;

2. DVD-R (RW): operating principle, design and main components, technical characteristics.

Principles of recording information on a DVD disc

The methods used to burn information to a DVD are similar to those used to burn a traditional CD. Currently, playback-only CDs, write-once CD-Rs, and rewritable CD-RWs are produced.

Principles of recording information on CDs, CD-ROMs, DVD-ROMs.

As shown in Figure 1 - a conventional compact disc (CD) consists of a transparent polymer substrate ( 1 ), metallized reflective layer ( 2 ) with "holes" ( B), with the help of which digital information is recorded, and a protective layer ( 3 ), necessary to impart rigidity to the disk. Reflective layer ( 2 ) in a regular CD and is a layer that stores information. It is manufactured using a factory method and is a kind of matrix with “holes” “stamped” in certain places, which indicate a logical unit. The absence of a "hole" implies a logical zero.
Information is read using a laser beam reflected from
disk surface. When reflected from the “hole”, the laser beam accurately hits a special detector, which outputs “1”. When reflected from a surface, the beam passes by the detector, which in this case recognizes "0". Absolutely the same principles of recording information underlie first-generation DVDs; they are intended only for reading information recorded on them in a factory way (the so-called DVD-ROM), CD-R, DVD-R.
In the compact disc record once (CD-R) design, between the substrate ( 1 ) and reflective layer ( 2 ) there is a pigment layer ( 4 ) from metal-stabilized cyanide (organic substance). In this case, it is the pigment layer on which the tracks are factory “extruded” ( A), along which the laser beam moves, stores information. When recording such a disc in special recorders, a high-power laser beam “burns” “holes” in the required places in the pigment layer ( B). When reading information, a laser beam of normal power freely passes through a “hole” in the pigment layer ( 4 ), reflected from the metallized layer ( 2 ) and hits the detector, which recognizes a logical one. In the absence of a “hole,” the laser beam is absorbed by the pigment layer, the laser beam is not reflected, and the detector outputs a logical zero. It should be noted that there is an additional rough layer for overprinting (5), on which the user, after recording information, can draw his own label using a ballpoint pen, a felt-tip pen, or even a special inkjet printer.

CD-RW, DVD-RAM.
The principle of recording on rewritable DVDs (which was originally developed for compact discs with the working title CD-Erasable) was proposed by Philips, Ricoh and Hewlett-Packard and supported by such companies as IBM, Sony, 3M, Olympus, Matsushita and Mitsumi. The compact disc rewritable (CD-RW) design is similar to a CD, but instead of a reflective layer, it uses a special substance ( 6 ), capable of repeatedly changing its structure. This material was developed by TDK and called AVIST; it has almost ideal characteristics.
Its high reflectivity (25-35%) is sufficient for DVD compatibility during playback. The characteristics of AVIST material are stable at both high and low recording speeds, which is especially important when working with various applications. In the case of rewritable CDs (eg CD-Erasable), recording takes place at speeds below 3 m/s. Working with data in the rewritable DVD-RAM format requires the working layer to have a write speed of 3 to 6 m/s. When working with compressed video information, the recording speed should already be above 6 m/s.
Excellent signal-to-noise ratio and phase change characteristics allowed TDK to achieve ultra-small marker sizes (less than 0.66 mm).
The new AVIST material can withstand at least 1000 rewrite cycles at speeds below 3 m/s. At higher write speeds, this number of rewrite cycles should increase.
Just like on the pigment layer of a recordable disc, tracks are “extruded” on the AVIST working layer ( A), directing the laser beam. When recording such a disc, the substance, under the influence of a powerful laser beam, changes its structure at the desired point on the surface, passing from a crystalline state to an amorphous one. Since such a transition is reversible (that is, the substance can be transferred back to the crystalline state), the disk can theoretically be rewritten an almost infinite number of times. It all depends on the properties of the material used in the information layer ( 6 ), and as it is further improved, the actually achievable number of cycles will increase and amount to at least five million rewrites. Reading is performed with a laser beam of normal power. When reflected from the surface of the disk, the phase of the laser beam changes depending on whether the reflection occurred from a surface area with an amorphous or crystalline structure. Changes in the phase of the reflected beam are recognized by the detector, which converts them into a digital stream. This method is called Phase Change Technology.
Single layer DVDs. As we have already noted, DVD is in many ways similar to CD, but differs significantly from it in recording density. As is clear from the recording principles described above, it is the maximum number of “holes” that can be placed on the surface of a disk that determines its information capacity.
The first step towards creating a new standard can be considered a sevenfold increase in the capacity of a CD due to an increase in recording density, which became possible thanks to the use of more advanced laser beam sources. differences in the size and density of the “holes”

Figure 2 shows the differences in the size and density of the “holes” in the working layer between DVD and CD discs.
Conventional CD-ROM drives use a 780 nm laser source that emits invisible infrared light. DVD players and DVD-ROMs use a laser emitting red light with a wavelength of 650 (635) nm. This reduction in wavelength made it possible to read smaller “holes” in the working layer of the disk, located in more densely spaced tracks (recording tracks). A corresponding increase in the numerical aperture of the lens (Numerical Aperture - the angle between the outer rays of the light cone entering the optical device) from 0.45 to 0.60 makes it possible to focus the laser beam with much greater accuracy. Only by increasing the recording density was it possible to increase the disk capacity to 4.7 GB.
In addition, digital modulation and error correction schemes have undergone significant modernization. The advanced high-efficiency modulation scheme (EFM Plus) operates in both 8- and 16-bit modes, ensuring compatibility with existing CD formats while allowing higher quality to be achieved with new DVD media. The new error correction circuit (RS-PC Reed Solomon Product Code) is approximately 10 times more efficient than that used in modern reading systems. single-sided single-layer disc (top) and single-sided double-layer disc (bottom)
Double layer DVDs. A further increase in disc capacity has been achieved through the development of a dual-layer DVD disc (DVD-9 standard). As can be seen from Fig. 3, a double-layer disk (lower diagram) has two whole working layers for recording information. To implement this model, a special translucent material was created for the outer information layer. When reading information from such a disk, the laser beam first passes through this translucent layer, focusing exclusively on the tracks of the inner layer (the principles of reading are described above). Having read all the information from the first (inner) layer, the laser beam automatically changes its focus, thereby changing the “penetration depth”, and begins reading information from the second (outer translucent) layer. The presence of two working layers allows you to increase the capacity to 8.5 GB. Since focus switching is almost instantaneous, and the use of an electronic buffer ensures that there are no interruptions in the outgoing digital stream, the dual-layer DVD model is intended to be used in applications that require large and “continuous” capacity.

The first layer of a two-layer DVD is stamped from ordinary polycarbonate-based plastics and carries the recording on one side. This side is then filled with a thin layer of translucent material, which in turn is covered with a film of photopolymer material, forming the outer working layer. The photopolymer material is hardened by ultraviolet irradiation, and the DVD is filled with transparent plastic, which serves as a protective layer for the disc. The main difficulty lies in creating a translucent material that separates the recording layers, since the requirements for it are quite contradictory: it must reflect the laser beam well (the required reflectance is about 40%) in the process of reading the outer layer and at the same time be as transparent as possible when reading the inner one layer. Priority in the development of such material belongs to 3M, which worked on behalf of Philips-Sony.

Double sided DVDs.
The total thickness of all layers of a DVD disc (both single-layer and double-layer) is only 0.6 mm, which is half the thickness of a CD disc. To be physically compatible with traditional CDs, the thickness of the DVD must be equal to the thickness of the CD, i.e. 1.2 mm. In a single-sided single-layer disc (DVD-5 standard), an additional 0.6 mm thick substrate is glued to the back side (the one where the CD label is located).

But this thickness makes it possible to produce a double-sided single-layer disc (DVD-10 standard). This idea was proposed by Toshiba. Structurally, the production process is as follows: two separate single-sided DVD discs are glued together with their back sides. As a result, the total thickness of the disc is the same as that of a standard CD - 1.2 mm, but such a disc can hold twice as much information; In addition, by reducing the thickness of the protective layer, the likelihood of information reading errors that occur in CDs due to random deviations of the laser beam in the transparent protective layer is reduced.
Thus, by combining (yes or no) two technologies for “doubling” the number of working surfaces, we obtain four structurally different DVD formats specified in the standard.
A single-layer, single-sided DVD-5 disc is primarily used for video films, as its capacity is sufficient for 92% of films, as well as for most computer applications, for which 4.7 GB of capacity is sufficient. At the same time, such a disc turns out to be a relatively cheap medium - its cost is only 14% higher than the cost of producing a traditional CD.
The next most complex disc type is single-sided, double-layer DVD-9. This type of disk is most widely used in applications where high capacity is a prerequisite without interruptions in reading.
Toshiba's DVD-10 (double-sided single-layer disc) format involves manually flipping the disc after playing one side; It is advisable to use it, for example, for duplicating very long films or TV series that do not fit on a single-layer, single-sided disc. Subsequently, with a further reduction in the total thickness of all working layers of the disc, it is possible to create a high-capacity double-sided double-layer DVD-17.

Technical characteristics with DVD disc specifications

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