Disks. This word means to the person familiar with the computer much. Different types of optical disks take not one decade a place of honor in racks and boxes of users. Pass years, new formats are added, but so far anything cardinally did not change. And though the flash-carriers (called in the people of "flash card") also pressed partially disks, first of all, as on the computer, but as the long-term keeper of information so far competitors optical disks have no source of transfer of information from the computer. So let's get acquainted with them closer.
The first optical disks were developed at a boundary of the 70-80th years by through joint efforts of the Sony and Phillips companies. Since then a lot of water flowed away. Twice considerably the technology of creation of disks for the purpose of increase in their capacity changed, recessions and rises, the competition and war of formats – under this sign took place these three decades.
But we, first of all consumers, truly? For us it is important to understand all that variety of optical disks which exists in the market, to get acquainted with their versions, features and the reasons of emergence. Let's pass to business?
CD (Compact disk)
Our first guest is a compact disk (CD) which appeared in 1982. Replacement of vinyl records with the modern, better carrier of audio of information and directly distribution of music was the purpose of its development. As a result there were disks containing 74 minutes of sounding that was quite enough for record of a standard audioalbum. Thus high quality of the music which is written down in the form of figures was provided. Originally the volume of such disk made about 650 Mb.
Kinds of compact disks:
CD ROM – this type of compact disks is produced at plants by method of stamping and is not written down carrier of data
The CD-R (CD recordable) – the disposable written-down compact disk. Standard volume – 700 Mb. Sometimes 800 Mbaytnye disks meet.
CD-RW (CD rewritable) – a re-recorded (reusable) compact disk. Standard volume – 700 Mb.
Re-recorded disks (it concerns also CD-RW and DVD-RW) cannot "eternally" be used. They too have the resource. Usually the figure of 1000 perezapisyvaniye is called. However in practice disks refuse quicker. On that is there are a lot of reasons, though most important, probably, this treatment of them.
Most often in a year of continuous use on RW disks there are multiple scratches and, as a result, problems with reading of information.
By the way, if once when using a disposable disk (R), it could be written down only once irrespective of, how many remained on it an empty seat, now, using multisession at record, it can be "finished", but it is impossible to erase all the same. At this InfoAdvisor.net reminds that multisessional disks are not always perceived by DVD players, especially old models. They can or not see a disk entirely, or will read only the first session (record).
In the early nineties were the format DDCD – a compact disk of the double density (double density compact disk) which contained twice more information, than a usual compact disk is developed. It was reached by reduction of the size pita. But these disks did not gain distribution because of incompatibility and high cost of production.
One more kind of carriers in the form of disks. It is developed in 1992 by the Sony company as replacement to compact cartridges, it is respectively used mainly as audioinformation carrier though since 2004 with the advent of the new Hi MD format it is possible to use for storage of any information. MiniDisk was not widely adopted. It is used mainly in players and video cameras by Sony and Sharp firms. Also they can be met as disks with drivers and utilities for computer peripherals, in particular, for the USB equipment (to "flash cards", Bluetooth-and WiFi-adapters and so forth)
DVD (Digital Versatile Disc)
In 1995 group of developers (Toshiba, Matsushita, Sony, Philips, Time Warner, Pioneer, JVC, Hitachi and Mitsubishi Electric) signed the agreement on joint cooperation in development and advance of new type of optical disks under the name Digital Video Disc (DVD) – digital video a disk. After DVD will begin to decipher as Digital Versatile Disc (a digital universal/multi-purpose disk) as over time these disks will begin to use for storage not only video of content.
The first DVD disks appeared in Japan in the fall of 1996.
What types of DVD disks exist?
DVD-5 – single-layer unilateral (Single_sided, Single_layer) a disk. Volume – 4,7 Gbytes.
DVD-9 – two-layer unilateral (Single_sided, Double_layer) a disk. Volume – 8,5 Gbytes.
DVD-10 – bilateral single-layer (Double_sided, Single_layer) a disk. Volume – 9,4 Gbytes.
DVD-14 – the bilateral disk having one information layer on one party, and on the second — two. Volume – 13,2 Gbytes.
DVD-18 – bilateral two-layer (Double_sided, Double_layer) a disk. Volume – 17 Gbytes.
The last two meet very seldom and in life are practically not used.
Kinds of DVD disks:
DVD-R (Recordable) – the disposable written-down DVD disks. Volume – 4,7 Gbytes.
DVD-RW (ReWritable) – re-recorded (reusable) DVD disks. Volume – 4,7 Gbytes.
Due to the big cost of the license for DVD technology, a number of the companies which gathered under the name "DVD+RW Alliance", in 2002 the DVD+R (W) standard was developed. Since then DVD disks began to share on pluses and minus. Now the special difference between them is not present. Though some also prefer to use more pluses (when using disks on the computer), for compatibility with old to use minus.
DVD+R (Recordable) – the disposable written-down DVD disks. Volume – 4,7 Gbytes
DVD+RW (ReWritable) – re-recorded (reusable) DVD disks. Volume – 4,7 Gbytes
DVD-RAM (Random Access Memory) – special re-recorded disks with direct access to memory which allow to work with them as diskettes, that is freely to write down, erase data. They are more expensive than usual disks and are less widespread.
DVD-DL (Double Layer) – the two-layer written-down DVD disks. Volume – 8,5 Gbytes. These disks are created by means of difficult technologies, are thus several times is more expensive than the usual. Therefore if you do not want to throw out money for a wind and to you it is necessary to use a two-layer disk for record, InfoAdvisor.net recommends to choose disks of famous producers, only they can provide the acceptable quality (for example, Verbatim).
Actually usual DVD disks have the volume not of 4,7 Gbytes, but 4,38 Gbytes. It is connected with that at number 4,7 conclusion – decimal numbers consider, i.e. 1 Kbayt=1000 of bytes, at the same time in the digital world is used binary system, at which 1 Kb = 1024 bytes
HD DVD & Blu-ray (BD)
The new generation of optical disks is represented by the disks HD DVD and Blu-ray (BD). Till February, 2008 they coexisted in the market as competitors, but after refusal of the Toshiba company (the main ideologist of HD DVD) to support the product, Blu-ray from the Sony company became the standard among disks for video of a high definition.
Disks and players of new generation cost so far rather much. Besides, InfoAdvisor.net would like to pay your attention that viewing of movies of a high definition requires the big TV which would support high display resolutions. And it too costs not much not. Therefore, the majority quite suits quality of movies on DVD and the new standard moves ahead on the market with a scratch. To force out DVD, it needs at least some years.
Blu-ray is translated as "a blue beam". In the word blue (blue) the last letter that there were no problems at registration of a trademark was purposely lowered.
Kinds of the disks HD DVD:
HD DVD-R (High Density DVD Recordable) – the disposable written-down disk. Disk volume – 15 Gbytes. If a disk two-layer – 30 Gbytes.
HD DVD-RW (High Density DVD Rewritable) – a re-recorded (reusable) disk. Disk volume – 15 Gbytes. If a disk two-layer – 30 Gbytes.
Kinds of the disks Blu-ray
BD-R (Blu-ray Disk Recordable) is the disposable written-down disk. The volume of such disk is equal to 25 Gbytes. If a disk two-layer – 50 Gbytes
BD-RE (Blu-ray Disc Rewritable) is a re-recorded (reusable) disk. The volume of such disk is equal to 25 Gbytes. If a disk two-layer – 50 Gbytes
HVD (Holographic Versatile Disc)
For several years essentially new format of the optical disks HVD (a holographic multipurpose disk) is developed. Unlike the previous formats which principle did not change (only width of paths, pit and laser wavelength changed), in this decision the technology of holography, that is saving of data in the three-dimensional volume of the carrier forms a basis (two lasers are used). Thus phenomenal capacity – information Tbytes on one disk, and the high speed of data transmission is reached.
Producers of optical disks
If you come into shop, specializing on the computer equipment, will see a set of different disks from the different producers, both widely famous and absolutely unfamiliar (and sometimes in general without identification marks). What here it is possible to advise? Everything depends on your requirements.
The difference in the price is usually insignificant. If you need a disk that to write down something, without calculation on long storage, can use practically any production. If you count on long storage and worry about reliability, then I would advise to buy disks from the producers checked by time, such as Verbatim and TDK. They are a little dearer, but is much more reliable and more qualitative. Extremely I do not recommend to buy the disks Digitex, especially re-recorded (RW), many are the share of them.
At all this remember – what even disks from the leading producers are not perfect. Also can sometimes bring you. From it it does not detsya anywhere. Besides except disks a lot of things depend on the drive and software of record.
About storage and use of optical disks
What there is a wish to tell about optical disks? Many think that this very well-tried remedy for storage of information, but it not absolutely so. Disks can be stored long, however, it is necessary not to forget about ways of storage. It has to be a dry, dark place. It is desirable to store disks in boxes. It is necessary to handle with them with care as scratches can make it unreadable. Though at record, so to speak, the reserve for when reading is also allowed, but it is not boundless. And sometimes after damage of a disk, it should be recovered … but it is a subject of separate conversation. Do not allow hit of dust on working area of a disk, in general it is the most gentle part of the carrier. To it be attentive. I had to see how people it seems and skilled, put disks working part on a table, a heap of papers, … anywhere and then were surprised – and why it is disks began to be read badly?
Before inserting a disk into a drive tray, attentively examine its internal ring on existence of cracks. Their emergence can lead to that at midpoint your data carrier will simply scatter on part directly in the drive.
By the way, and what to do if the drive with a disk does not open? If standard ways of opening did not help, InfoAdvisor.net advises to use mechanical (do not worry, it is not necessary to disassemble the drive for this purpose). At first take a usual office paper clip and straighten it. Then look at the front panel of the drive. The majority of them has small (1 mm) an opening. We switch off the computer and we insert the straightened paper clip into an opening. We press and the tray of a disk has to on open slightly. We cling it a hand and we open completely. We get a disk. This way can be used and if you switched off the computer, having incidentally forgotten a disk which is necessary to you in the middle.
It is also necessary to remember, what even without damages disks, having lain year - another, can become unreadable. Therefore if you have very important information, it is better periodically for its peresokhranyayta.
And finally banal caution. Do not forget that it is possible to write on a disk only with a special marker. And only on the top, non-working surface.
Of course, safety of your information is influenced also by other factors. For example, what drive you use, what use. And it is simple as write them. But it is a subject for separate conversation. Also we will talk about it next time.