Information is read using a focused beam of a laser beam.
Now let's see how this DVD Rom works. Today it is still relevant, since many people still use disks as storage media. Therefore, you need to navigate this issue. But we won’t pay attention to other drives for now.
In general, only the advent of high technology made it possible to create such a thing as an optical drive. The disk has a reflective layer on which the laser beam is focused. It must be impeccably accurate and targeted. The layer on the disk seems smooth and shiny to us, but there are microscopic depressions there, which are nothing more than recorded information. The laser beam reads the reflected light from these “irregularities”.
First of all, order
But to make it clearer, we will consider everything in order.
Does everyone know what the abbreviations we already know stand for? I think not. So let's get this out of the way first.
- The abbreviation for CD Rom is compact disc. The full name is Compact Disc Read-Only Memory and it is used for reading only.
- Also, a short DVD Rom is a more universal disc. However, it is also used for reading only. Full name Digital Versatile Disc read only memory.
- There is her “blue ray” or Blu-ray. Information is recorded on this disk using a short-wave laser beam, blue-violet in color.
The picture clearly shows what exactly we call a DVD optical drive.
Installing DVD Rom yourself is easy. Usually it does not cause any difficulties. But it is important that the connection standard matches the device. There are two standards: “SATA” and “IDE”.
The first is considered the most modern, and the second is already outdated.
The most important things are indicated by numbers in the order of one to three.
- The first is the “master/slave” section of the jumper on the disk.
- The second number is the pin interface for connecting “ATA/ATAPI” devices. All nineteen holes.
- The third connector of four contacts is where “molex” is connected.
Now let's turn our attention to the back side. This is a SATA standard DVD Rom drive.
- The first connector is connected to a power cable consisting of fifteen contacts.
- The second connector is where the data cable is installed. It is flat and short. The connection occurs to the “SATA” controller located on the motherboard.
It should be noted that not all devices have a DVD Rom drive. For example, a netbook or tablet. In this case, an optical drive such as a USB DVD Rom will help out. After all, if you change the operating system, for example, there is nowhere to insert the disk. Then the optical drive is connected via a USB port.
Situations when this type of optical drive is necessary are not uncommon. For example, this netbook requires installation of an operating system, which can be done using this USB drive.
How is information recorded?
Many people more or less understand how recording on gramophone records occurs. At first, recording onto CDs happened in a similar way. And the name of the records was CD-R (Recordable). It was impossible to record something a second time on such a record. But then the disks became more and more advanced and it became possible to rewrite information several times. This CD-R discs W (ReWritable). And it's all about the nuances of production. Previously, recording took place directly onto a layer of plastic. Now a layer of metal alloy was made. And this layer under the influence of a laser beam is capable of changing its properties. You may even notice dark and light stripes on the surface. This technology allows you to rewrite information many times, maybe even a thousand times.
The disk platter has a layer onto which recording is made. This layer can be seen on all recording and rewriting discs. If the disc cannot be rewritten, then this can be determined by the layer on the platter. If the disc is recorded, the layer will change color. The process occurs from exposure to a laser beam and is irreversible.
Rewriting discs are equipped with an alloy layer that can change the reflective layer under the influence of the same laser beam.
All discs have standard size diameter 120mm. The thickness does not exceed 1.2 mm. In the center there must be a hole with a small diameter of 15 mm. Under no circumstances should the surface of the disc have any scratches. And to prevent this, there is a protrusion on the outside of the disk. It is small 0.2 mm, but strictly performs its functions. On a flat surface the disc will not receive any damage.
Any disc is a multi-layer cake. But the pie is a little more than a millimeter thick. However, each layer has its own function and performs it. Look at what the disk looks like in the diagram and how many layers it has of different materials.
No matter how complex the information is from our point of view, all of it will be recorded in the form of pits and landings. In fact, these are recesses (pit) and surface (lands). In general, the result is a wavy path. The recesses are pressed into the polycarbonate layer, and the plane remains unchanged. When the beam is focused on a track, the light from the plane and the bumps is reflected differently. And the difference can be barely noticeable, but all this is recorded.
More to the point in simple language, then all the information looks like zero - a plane and one - a tubercle.
Notice how it looks under high magnification.
Now see what's on the surface that seems perfectly flat?
DVD Rom writes and reads information using a red laser. The wavelength is measured in nanometers and is 650 nm. But the pitch is only 0.74 micrometers. For comparison, in CD discs all indicators are twice as large. It is clear that reducing the laser wave made it possible to more accurately “examine” the surface of the disk and record all the pits. The constant reduction made the DVD disc almost dimensionless. At one time, when more than 4 gigabytes of information began to fit there, it looked fantastic!
Here are some numbers for comparison.
In a DVD disc, compared to a CD, the pit size is 0.4 microns versus 0.83.
A CD disc has a track width of 1.6 microns, while a DVD disc has only 0.74.
Some disks can simply hold a huge amount of information. For example:
- bilateral,
- two-layer.
Some discs can be either double-layered or double-sided. This sandwich will hold all 17 gigabytes.
More details about each
Double-layer DVDs are produced by pressing the first layer. Then the second layer is sprayed on top. The coating is translucent. The laser beam, when reading information, focuses on each layer, moving from one to another automatically.
If a DVD disc has two layers, then the thickness of each layer reaches 0.6 mm. When gluing the layers, the same 1.2 mm is obtained. It's very similar to a record; after listening to one side, you can turn it over.
In the diagram it looks like this:
Disk layout blue beam
Remember Blu-ray discs? They are somehow different from the usual DVDs and CDs. They are read using a blue-violet laser beam. Its length is less than required for reading DVD Rom and CD Rom (RW) discs. They use a beam length of 650 and 780 nanometers, respectively. But for a Blu-ray disc, the beam is only 405 nm long. And all because technology using a red laser beam can be said to have reached its limit. But the blue-violet ray is a real leap in development.
For such a beam, the width of the track is required less, and therefore the amount of information can be recorded more. However, due to the thinness of the relief on the information layer, it has become more difficult to read records at high speed. Therefore, it was necessary to reduce the protective layer of polycarbonate. Previously it was 0.6, but now it is 0.1 mm. As a result, the speed of work and the accuracy of reading information have increased.
An optical drive is a data storage device that reads and writes optically. The optical drive uses flat multilayer disks with a diameter of 8 or 12 mm as media. Among the “optics” there are several main types of these devices: CD-ROM, CD-RW, DVD-ROM, CD-RW-DVD, DVD-RW. These are not all of the listed types optical drives, there is also Blu-ray and so on, however, we do not set ourselves the goal of talking about all devices of this type, but we only want to touch on the main ones that are present on the market and are relevant and not very relevant today. Again, it’s pointless to touch on the topic of Blu-ray, etc., there is a huge amount of information on this type of device on the Internet. In addition, Blu-ray drives are quite expensive today and are not in great demand. When these optical drives become available to the average consumer, we will definitely consider them as a potential purchase option.
We want to start our story with a story about the types of optical drives.
Types of optical drives
CD-ROM
The simplest of devices of this type. This drive can only read regular CDs. The speed of most “modern” CD-ROMs reaches 52x, less often maximum for of this type 56x devices. We'll talk more about speed below. Today, the CD-ROM drive is obsolete and is of interest only in the most exceptional cases. Take, for example, the same office and a limited budget. It's hard to fit a CD-ROM even here. Usually in offices there is the local network, and buying one DVD-ROM drive for one of the personal computers is more than realistic. There is no attractiveness in CD-ROMs; CDs are not much cheaper than regular DVDs, and their capacity is much less.
CD-RW
The next stage in the development of optical drives. CD-RW allows you not only to read information from regular CDs, but also to write it to CD-R and CD-RW matrices. The relevance of CD-RW is also in question, only in the office - and then in exceptional cases.
DVD-ROM
Another stage in the evolution of optical drives - now you have at your disposal a device that can read not only regular CDs, but also DVDs. The speed formula of the device is as follows: 16x for DVD and 52x for CD. The prospect of buying a DVD-ROM is much brighter compared to its progenitor, the CD-ROM: examples of use are obvious of this device to download any information or software from DVD media and CD.
DVD-CD-RW Combo
The so-called Combo drive, which combines the functions of devices such as DVD-ROM and CD-RW and, accordingly, can write CD-R and CD-RW discs and read both regular CDs and DVDs.
Some time ago, DVD-CD-RW was the most popular optical drive, but its prospects are questionable. These devices are practically never produced, although there is a very small supply on the market. We see some prospect of using DVD-CD-RW in an office or educational institution, when you need to burn CD-R and CD-RW discs and load information from CD and DVD media, but the budget is very limited, and you want to save at least a small amount money.
DVD-RW
DVD-RW is the undoubted leader in the optical drive market today. These devices are most popular on Russian market information technologies. DVD-RW allows you not only to read CD/DVD discs, but also to write both regular CD-R/CD-RW media and much more capacious DVD-R/DVD-RW/DVD+R/DVD+RW. And in the case of a Super-Multi drive, DVD-RAM will also be added to support a significant list of formats.
The prospects and relevance of this type of device are beyond doubt. For a price of about 40-55 USD, you get an optical drive that has sufficient functionality for most consumers. It's hard to imagine a modern home personal computer without DVD-RW.
DVD-RW is the most attractive device today in terms of format support, capabilities and price. If you are going to purchase an optical drive, then it should undoubtedly be a DVD-RW.
From the type we smoothly move on to the form factor of optical drives.
Form factor
Optical drives are available in several form factors. On the Russian market you can find these devices in both internal and external versions.
The most common are internal drives, which are installed in the 5.25-inch bay of a regular desktop case. Such devices are the most popular and in demand on the market at the moment.
5.25" DVD-RW drive
5.25" DVD-RW drive
Among such devices, two so-called subtypes can be distinguished, which are characterized by the possibility of loading: tray and slot. In the first case, the CD is placed in the eject tray; in the second, it is simply inserted into the slot, and the device takes it away.
Optical drives designed for laptops are also available. Their form factor can also be described as internal, but they are made in the so-called Slim design, which, in general, is not surprising, given the size of modern mobile personal computers.
Laptop DVD-RW drive
Laptop DVD-RW drive
As is the case with 5.25-inch devices, “Slim-optics” has several options for loading media into the drive: slot and tray. The principle is the same, you just have to make a reservation that the tray in Slim drives does not come out automatically, but only opens slightly and is subsequently pulled out manually.
Interface
Interface
Internal drives are equipped with two interfaces: Parallel ATA and Serial ATA. If you have enough Serial ATA ports, you can buy an appropriate optical drive, but you won't notice much of a difference in the device's performance. Still, there are pleasant bonuses in the case of using a serial interface: a thin Serial ATA cable is more convenient to install in a case than 40 or 80-wire IDE analogues, and the prospect of an upgrade is not scary: it is very unpleasant that one fine day, after changing the system board, you will have to buy a new drive. The trend towards reducing IDE connectors in modern motherboards is obvious; chipset manufacturers no longer support Parallel ATA; motherboard manufacturers themselves do this, equipping their products with chips from third-party manufacturers.
In addition to internal optical drives, there are also external ones. These devices are connected to personal computer via USB or FireWire interface. The design of such devices is quite diverse - there are large, angular models in the “square-practical-gut” style with an external power supply that require additional power from the mains, and there are also very stylish Slim models that can work without additional power, content with the fact that available in USB 2.0.
Slim model of DVD-RW drive
Slim model of DVD-RW drive
The market share of external optical drives is small. As a rule, these devices are used in conjunction with single-spindle laptops, which have no drive at all. However, it is worth mentioning that there are few such laptops.
Having considered the types and form factors of optical drives, it’s worth talking a little about formats.
A little about formats and speed
You may have already noticed that the read/write speed of optical drives is measured in so-called Xs: 1x, 16x, 48x. It is worth clarifying a little and linking the so-called X to a more specific parameter that measures speed. So, for ordinary CD media the speed of one X is 150 KB/s, and for DVD discs this parameter is already 1.385 MB/s. One more feature can be noted in reading CDs and DVDs. Thus, the latter rotate at a speed three times higher than the reading speed of conventional CD media. Using arithmetic, it is easy to see that 16x for DVD is similar to 48x for CD.
We've more or less figured out the speed, now let's look at the main formats that modern optical drives read/write.
CD- the most ordinary stamped CDs that are used exclusively for reading. Music, software and other information - you could have seen all these CDs repeatedly in various stores. The maximum capacity of this type of media is 700 MB. Speed characteristics range from 40x to 56x. It is worth noting that for most CDs this parameter is 40x, 40x or so; 52x and 56x are rare. At such high speeds, optical drives simply howl, especially if the media itself is of poor quality.
CD-R– CDs for one-time recording of information. The speed characteristics for the reading parameter are similar to their CD counterparts. As for recording, the maximum speed at which a standard 700 MB CD-R can be written is about 40x and 48x, in practice this is 3-4 minutes. Intermediate speed values are also available. That is, if your optical drive does not support this high speeds records or you yourself for some reason do not want to write matrices on the maximum possible x, you can limit yourself to 1, 2, 4, 8, 16, 24, 32x.
CD-RW– rewritable CDs with a resource of about 1000 times. The capacity is the same as CD and CD-R, but the reading speed is slightly lower: most media are read at 32x and 24x speed. CD-RWs are clearly tied to a specific write/rewrite speed: CD-RW (1-4x), Hi-Speed CD-RW (4-12x), Ultra Hi-Speed CD-RW (12-24x) and Ultra Hi-Speed+ CD-RW (24-32x). As you can see, the speed flexibility of CD-R is not here, but do not be upset about this, modern optical drives support maximum write/rewrite speeds for CD-RW and are backward compatible with slower matrices.
DVD-ROM– stamped DVDs. Such media can be found in any video store that sells films. There are both single-layer and double-layer media on sale, which differ in capacity: 4.7 GB (single-layer) and 8.5 GB (double-layer). The maximum reading speed is 16x.
DVD-R and DVD+R–DVD matrices for one-time recording of information with a capacity of 4.7 GB. In terms of reading speed, such CDs are similar to their stamped counterparts, 16x is the maximum; if the optical drive is old, then it can read DVD-R and DVD+R at lower speeds: 8x, 10x. There are practically no differences between plus-discs and minus-discs, these designations remained from the time of the format war, today all this is no longer relevant, and modern optical drives support both plus and minus discs.
The maximum recording speed of these media is about 16x, which corresponds to a time period of 6.5 minutes. However, the speed flexibility of CD-R is inherent in both DVD-R and DVD+R, so you can record these discs at speeds below the maximum 16x: 1x, 2x, 4x, 8x.
DVD-R DL and DVD+R DL– These compact discs are similar to DVD-R and DVD+R, but have not one layer, but two, and, as a result, their capacity is about 8.5 GB. In terms of read and write speeds, they are significantly inferior to their single-layer ancestors: reading – 8x, and in most cases it is 4-6x, writing – 8x for DVD+R DL and 4x for DVD-R DL.
DVD-ROM drive(DVD-ROM drive (DVD-ROM drive, DVD-R/RW drive) - a computer device designed for reading optical disks high-density recording (DVD), as well as playback of audio, video and CDs. Writing models DVD-RW drives, which by 2006 began to dominate the market, are capable of not only reading, but also writing/rewriting discs various formats(DVD and CD).
Data is read/written to DVDs in the same way as regular CDs (see CD-ROM drive), but DVD drives use a reduced laser beam (to 0.63-0.65 µm vs 0.78 µm in CD-ROM) of a long wavelength, which makes it possible to distinguish pits of smaller sizes (0.4 μm versus 0.83 μm in CD-ROM), which, together with a decrease in the distance between the turns of the track and other technological features, significantly increases the recording density on the disk. In addition, the use of a narrower laser beam in DVD drives led to a reduction in the protective layer of the disc by half, which made it possible to create double-layer DVD discs (DB, double layer) and double the storage capacity of the media. Modern DVD drives can change the focus of the laser beam, allowing data to be read from layers of a single-sided disc located one below the other. To read/write double-sided discs, drives with two independent laser heads can be used. Modern disk drives are capable of changing the wavelength and radiation power to read/write various CD formats (DVD and CD). Like CD-ROM drives, DVD drives differ in data transfer speed, access speed, buffer capacity, support for certain disc formats (including DVD-R/RW, DVD+R/RW, CD-R/RW) and recording methods, as well as other characteristics.
Reading speeds/ DVD recording-disks are designated by a multiplier (x1, x2, etc.) similar to the designations of the corresponding CD-ROM speeds, however, the unit of speed here is not 150 Kb/s, but 1, 321 Mb/s (video reading speed). For playing DVD movies, the maximum possible read speed is not important since all movies are played at the same speed, but the speed of the drive may be important when writing/reading data.
Mass production of these drives began at the end of 1996, but their widespread introduction was delayed for more than a year. This was due, in particular, to the fact that the first versions of drives did not allow playing regular CD-ROMs. In addition, mass production of recordings on DVD-ROM had not yet begun and users did not yet have a sufficient number of recordings. However, it was already assumed from the outset that DVD drives and discs should oust the corresponding CD-ROM technology products from the market within a relatively short period of time. The beginning of active production and distribution of drives and disks of this type can be attributed to approximately the second half of 1997. American producers of film products and game programs showed the greatest activity in using the new medium.
At the end of 1997, second generation technology (DVD-2) appeared. Products produced using this technology do not have a number of disadvantages of earlier releases of devices that cannot read CD-R and CD-RW media, which are becoming increasingly popular as their prices decrease. Additionally, these drives are faster than DVD-1 drives. By the beginning of 1998, a significant number of games and films in MPEG-2 format were released on these media.
How to choose a DVD drive for your computer
The fact that DVD media is slowly but surely disappearing into oblivion is difficult to dispute. They repeat the fate of their predecessors - floppy disks and CDs. No “revolutionary” solutions such as the release of double-layer or double-sided DVDs could radically change the situation, and the digital media market in small batches is falling into the hands of flash memory and Blu-ray disc manufacturers. However, the DVD format is still the most widespread in the distribution of movies, software, games and music (together with CDs), so the DVD drive is still considered an integral part of a personal computer.
Let's start, as usual, with the basics. “Scientifically”, a DVD drive is an optical drive, a device designed for reading and writing data from digital media, which, in particular, includes CD-R, CD-RW, DVD-/+R and DVD-/ +RW. Many still remember the times when a DVD burner was more of a luxury than a necessity. Today, finding a simply “reading” disk drive on sale is almost impossible, and there is no particular need for it. Even if you rarely or never use this function (recording), this has practically no effect on the final price, so it makes no sense to purchase a regular DVD drive or even a CD-ROM writer. Unless you collect them.
If you buy a computer from scratch, then by default the internal one (packed in system unit) A DVD drive is included in the package. This applies to both desktop PCs and laptops with netbooks, although the latter are equipped with their own, thinner and more expensive, drive models. The need to separately purchase a DVD drive may arise for only two reasons. Either your drive has failed for some reason (there can be many reasons - from factory defects to carelessness in operating the device), or this model you are not satisfied with some parameters (noise, speed, design, compatibility), but we managed to find out this only while working with the drive.
Drive speed and major media formats
The question arises, what could be wrong with this or that drive? Main parameter, which is supposedly worth paying attention to is the read and write speed. Because in fact, you can only experience this speed if you are going to read or write disks on a truly industrial scale. It is also worth deciding what media you will most often “feed” the device, because the same CDs are read much slower (more than 9 times) than DVDs. It is logical to assume that if most of the information on the market today is sold on DVD media, then you will mostly be stuffing discs of this format into the drive.
Drive speed is indicated in 1x, where 1 corresponds to 150 Kb/s for CD-ROM, and 1.385 MB/s for DVD-ROM. The maximum volume of a standard CD, on which music albums and small ones are most often found on sale now computer games(as well as databases and software), is 700 MB. By today's standards, the size is ridiculous, but quite sufficient for recording a dozen uncompressed music tracks, text files, programs or disk with corporate information (catalogues, price lists, instructions, etc.). Theoretically, the CD reading speed is limited to 56x, but in practice this figure does not exceed 40x, because the faster the disk rotates in the drive, the more noise it creates during operation.
If you often and enjoy writing discs CD-R (one-time use) And CD-RW (rewritable), then your ability to read these media will be limited to speeds of 40x and 48x, or even 24x (for CD-RW). As for recording, by default the drive will operate at the maximum possible speed, which can be manually changed to a lower speed. 700 megabytes usually fills up within five minutes.
Now let's turn directly to DVD discs, which you will encounter most often, both during the reading and writing process. We remind you that data exchange with DVD media can only be carried out using a DVD drive; a regular CD-ROM cannot cope with this function by definition.
Currently, the following DVD discs are distinguished. This is first and foremost the most common DVD-ROM, which is the basis for film products, games, software and other data produced and sold in series. Writing to DVD-ROM at home is impossible, read only. DVD-ROMs come in single-layer and double-layer formats, with capacities of 4.7 and 8.5 GB, respectively.
The most common disc formats that you will encounter are disposable discs DVD-R and DVD+R, which are most often used to store “heavy” information such as video and software. Why plus and minus? It's simple, negative disks appeared a little earlier at the instigation of the famous company Pioneer, while “plus” technologies belong to the pen of Sony and Phillips. The difference lies in the presence of special markings that make it easier to position the drive head, and the use of different reflective material. At first, these differences were critical for the quality of multiple rewrites (of course, for DVD-RW and DVD+RW discs), but today most drive models can easily cope with any version.
Maximum read and write speed per DVD-R discs and DVD+R is, depending on the drive model and the quality of the disc, from 8x to 24x, which when fully loaded with data will be approximately 4 to 8 minutes. There are also two-layer disposable discs with the prefix DL (dual layer) in the name, with a capacity of 8.5 GB. However, the recording speed on these “giants” is no more than 12x.
Media that support rewriting are distinguished between DVD-RW, DVD+RW and DVD-RAM. You've probably already encountered the first two: 4.7 GB disks with a maximum write speed of 8x. As for DVD-RAM, which can be written to simultaneously with the process of reading data, their mass use is limited due to the prohibitive cost.
What else do you need to know about DVD drive speed? Considering the fact that this parameter of the device directly depends on the media used in it, it is not advisable to strive to buy the fastest drive. Discs that support high write and read speeds are expensive and are not sold everywhere. Remember that discs are extremely fragile media, susceptible to scratches, chips and other physical surface deformations. At high rotation speeds, such interference can lead to the destruction of the disk, which simply shatters into fragments and can cause irreparable damage to the drive. As they say, the quieter you go, the further you will go.
Features of connecting the drive and sales packaging
Probably everyone has seen a regular internal disk drive. A rectangle (148x42x198 mm) without unnecessary design frills, weighing under a kilogram. There are also shortened versions (for compact cases) with a length of up to 170 mm and lightweight ones up to 750 grams. The most elegant are, of course, DVD drives for laptops - square in size (130x130 mm) with a thickness of only 13 mm and a weight of 120 grams. However, these devices are very expensive and capricious in terms of installation, which is best left to professionals.
Appearance of a DVD drive for a laptop
DVD drive, being internal device, is connected using a cable to the computer motherboard, and therefore there are two types of connection - through the parallel IDE interface or serial interface SATA. IDE is now being widely replaced by the more advanced SATA, so when purchasing a drive separately, you should check the insides of your computer, or rather, the connectors on the motherboard, so as not to get into trouble. New board models most likely already work with SATA, so you can safely purchase the appropriate drive. What's the advantage? Theoretically - in speed. But in practice, you most likely will not notice the difference.
Regarding packaging. The fact that used drives are not worth buying is, I hope, clear without further ado, because all computer components have their own limited resource. The store will offer you two options: OEM and Retail. OEM is a package “for the poor”, which includes a plastic bag plus a disk with installation software. As part of the Retail kit, in addition to the drive itself, you will find wires (cable), screws, blank disks, and if the manufacturer is generous, then an audio cable and even replacement panels. Naturally, the second option will cost you a little more than the “polyethylene” one.
Manufacturers and prices
It's no secret that in the niche of DVD drives, a brand or trademark often becomes the determining factor in choosing a particular device. There are many different elements in the system unit, ranging from motherboard, video cards and ending with the power supply and, in fact, the system case itself. But all these components, as a rule, are impersonal, because not everyone would think of going inside to look at the manufacturer of the sound board or motherboard. Many, not very advanced, users focus more on specific parameters rather than on company names. It’s different with DVD drives; they are “facing” the consumer, proudly decorating the system unit with an inscription like NEC, Sony or Plextor.
There is always a lot of subjectivity in the selection of a specific brand, because few people have to test drives from different manufacturers at home. Usually we become attached to a particular model, after which we don’t even want to hear about its replacement with something else. Nevertheless, there are quite a lot of players in this market, which we will talk about at the end of the article.
DVD-ROM from Plextor
If you have to deal with the recording process often and a lot, then there are actually two options. Either constantly change cheap devices, or occasionally face the need to buy expensive models. For both of them, the resource is a parameter with a finite value. If you are more satisfied with the second option, then pay attention to the quality of the company Plextor, whose devices are characterized by high reliability and performance. The cost of Plextor drives is not the only, but the most significant reason why only a select few can afford to communicate with this brand (from 5,000 rubles and above).
The situation is approximately the same with the products of American companies. Dell And Hewlett-Packard (HP). Good, even remarkable quality, high operating speeds, reliability, but the price in the region of 4000-5000 rubles will not please everyone. Moreover, their products are rarely seen on store shelves, and Dell prefers to specialize in ultra-thin laptop models.
Drives available with label ASUS And Sony Optiarc (since 2006, the official merger of two companies - Sony and NEC)- strong middle peasants. At a cost of around 1,000 rubles, they demonstrate high recording quality, and discs created using these drives can be read without problems by devices from other manufacturers, as well as by many DVD players. Quiet, stylish, practical - optimal value for money.
DVD-RW drive Sony Optiarc
Drives from Samsung, Toshiba and Pioneer are considered the most capricious in terms of blank quality. LG and Lite-On drives handle scratched media better than others. Of course, these conclusions were made during testing specific models, which, as we know, can be both successful and not so successful. In other words, you may be incredibly lucky and your Samsung DVD drive will be omnivorous and tireless, while the ASUS drive, highly rated by “experts,” will stumble at every step.
In any case, when buying a DVD drive, pay attention to three things: packaging (OEM or Retail), connection method (IDE or SATA) and speed characteristics. Well, and the design, of course, because a black NEC sticking out on a white case will be striking. Each brand has its own advantages and disadvantages, but in this market, unless we are talking about elite models of semi-professional quality, the main and determining factor is still the price of the device, which for the vast majority of DVD drives varies from 600 to 1,500 rubles.
It would seem like a banal thing: an optical drive (aka CD Rom, Dvd Rom or Blu-ray). All these are devices of different generations for reading and writing optical laser discs. Laser because reading and writing to them is carried out precisely by a focused laser beam.
In this article we will consider the DVD Rom device, since it is the most common on this moment, but we will also touch on other types of drives. In fact, an optical drive is quite a technological thing. The laser beam must be very precisely and precisely focused on the reflective layer of the disk in order to read the reflected signal at its microscopic depressions.
But let's not get ahead of ourselves! We will move forward gradually.
First, let's look at abbreviations (accepted abbreviations).
- CD Rom - (Compact Disc Read-Only Memory) - read-only CD
- DVD Rom - (Digital Versatile Disc read only memory) - read-only digital universal disk
- Blu-ray - (blue ray) - recording using a short-wave blue-violet laser
Here is a photo of the DVD optical drive:
The button for removing the tray is marked in red.
The (RW) itself will not cause any difficulties. The only thing you need to pay attention to is the connection standard of the device. This can be either the “IDE” (outdated) connection option, or the modern “SATA” connection option.
Let's look at back panel DVD Rom optical drive with an “IDE” connector, which is shown in the photo below:
Let's take a quick look at the numbers:
- Master/slave section
- 19-pin interface for connecting “ ” devices
- Four pins for molex power connector
Now let's look at the back of the SATA DVD Rom drive:
- Long flat (15-pin) power cable
- Short flat (7-pin) data cable (flex cable connecting to SATA controller on )
One cannot ignore such a type of optical drive as USB DVD Rom (RW). Such devices, for example, are very helpful in situations where you need to install operating system to a device that does not have an optical drive. These include all kinds of tablets and netbooks.
In our IT department, we regularly use this USB drive. Here is a photo Windows installations XP on a netbook from Asus.
This, in fact, could be the end of this article, but I would also like to consider the very principle of recording laser discs and their structure. To complete the picture, so to speak :)
The structure of optical DVD discs and the recording principle.
The first CDs were recorded like gramophone records: once and forever. They were called CD-R (Recordable). But very soon discs for repeated rewriting appeared - CD-RW (ReWritable). Their manufacturing technology is different. Information is recorded not on a layer of plastic, but on a film made of a special metal alloy, which changes its properties under the influence of laser heating and forms alternating dark and light areas. They can be rewritten up to a thousand times.
Recordable and rewritable discs have a thin recordable layer on the top side of the platter. In write-once discs, it consists of an organic dye that irreversibly changes its properties under the influence of a laser beam. In rewritable ones, instead of this layer, there is a film of a special alloy, which changes its reflectivity depending on heating and cooling (under the influence of the same laser).
Externally, all (standard) laser discs look the same. They are based on a polycarbonate plate, which has a diameter of 120 mm and the thickness of everything 1.2 mm. In its center there is a hole with a diameter of 15 mm. In addition, on the outer surface of the carrier there is an annular protrusion with a height 0.2 mm, allowing the disk, placed on a flat surface, not to touch it, which prevents scratching the surface.
The amazing thing is that a thickness of just over a millimeter can accommodate many reflective layers and various types surfaces. Inside, the carrier is like a layer cake, each layer in which performs a strictly assigned role. Here's a schematic diagram of a standard optical disk.
Information on the disk is recorded in the form of a spiral track. This path consists of pits (pits) pressed into a polycarbonate base. The spaces of a flat surface between the pits are called land.
An optical drive focuses a laser beam onto the surface of the disc. Pits and lands reflect light differently, and the optical sensor records this difference. Measurement results can be converted to their original digital (binary) form. Roughly speaking: the tubercle is a digital unit, and the depression is zero.
This is what the surface of a DVD optical media looks like under an electron microscope.
Here we clearly see these same depressions and tubercles.
To read and write DVD Rom uses a red laser with a wavelength of 650 nm. (nanometers) and track pitch - 0.74 microns. (micrometer). This is more than half the cost of a regular CD. It is precisely the reduction in laser wavelength (which makes it possible to read more small parts surface of the disk) and the size of the “pits” made it possible, in due time, to fit on DVD disc 4.7 gigabytes of data.
To imagine how miniature things an optical drive (DVD Rom) deals with, we present some digital data. In a DVD disc (compared to a CD), the size of the “pits” has decreased from 0.83 to 0.4 microns, and the width of the spiral track has decreased from 1.6 to 0.74 microns. Hence the increase in recording density.
Moreover, disks can be:
- bilateral
- two-layer
- double-sided and double-layered at the same time
This increases the total volume of one such “sandwich” to 17 gigabytes!
Double-layer manufacturing technology DVD discs boils down to the fact that the first layer is obtained by pressing, and the second, additional translucent, is sprayed on top of it. As the recording is played back, the reading laser moves from one layer to another, automatically changing focus.
The optical drive can also handle double-sided discs. Each of them has a thickness of 0.6 mm (with two layers), then with the help of a reinforcing compound they are glued together, which gives a total of the required thickness - 1.2 mm. It turns out something like a double-sided, two-layer vinyl record that can be turned over.
Here's how everything described above can be depicted schematically:
In conclusion, I would like to say a few words about Blu-ray optical disc technology. Here, a blue-violet laser with a wavelength of 405 nm is used for reading and writing. Conventional DVD Rom and CD Rom (RW) use red and infrared lasers with wavelengths of 650 nm and 780 nm respectively. But this red laser technology was gradually approaching its physical limits, so a new quantum leap forward was required.
Reducing the laser beam width made it possible to narrow the recording track by half compared to a conventional DVD disc, thereby further increasing the data recording density. Since the relief of the information-carrying surface of the disk became even smaller and data at high speed became more difficult to read, the developers had to reduce the thickness of the protective polycarbonate layer by six times (from 0.6 to 0.1 mm). This made it possible to physically bring the information layer closer to the laser itself, increasing the speed and accuracy of the latter.
The operating speeds of Blu-ray optical drives are presented in the table below:
After this, TDK developed a special protective coating called “Durabis”, which made it possible to protect this type of optical media from mechanical damage.
A single-layer Blu-ray can store 25 gigabytes of data, a double-layer Blu-ray can hold 50 GB, and a double-layer double-sided can hold 128 gigabytes. The Japanese company Pioneer demonstrated experimental 16 and 20 layer structures!
As you can see, the topic of DVD Rom and optical drives is not as boring as it might seem at first glance :) Let's hope that the developers will continue to delight us with technical innovations in this area. And with that, let me take my leave for today :)
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