FDD(Floppy Disk Drive) - A device for recording information on removable magnetic disks (floppy disks).
Diskette- portable magnetic storage medium used for multiple recording and storage of data of a relatively small volume. This type of media was especially common in the 1970s and late 1990s. The abbreviation is sometimes used instead of the term "floppy disk" KMT- "floppy disk" (respectively, the device for working with floppy disks is called NGMD- "floppy disk drive").
Typically, a floppy disk is a flexible plastic plate covered with a ferromagnetic layer, hence the English name "floppy disk". This plate is housed in a plastic case that protects the magnetic layer from physical damage. The casing is flexible or durable. Floppy disks are written and read using a special device - a floppy disk drive (floppy drive).
Floppy disks usually have a write protection feature, through which you can provide read-only access to data.
1971 - The first 200 mm (8?) Floppy disk with a suitable disk drive was introduced by IBM. Usually the invention itself is attributed to Alan Sugart, who worked at IBM in the late 1960s.
1973 - Alan Shugert founds his own firm, Shugart Associates.
1976 - Alan Schugert develops the 5.25 ″ floppy disk.
1981 - Sony introduces 3.5? (90 mm). In the first version, the volume is 720 kilobytes (9 sectors). The later version has a volume of 1440 kilobytes or 1.40 megabytes (18 sectors). It is this type of floppy disk that becomes the standard (after IBM uses it in its IBM PC).
Later, the so-called ED floppy disks appeared (from the English. Extended Density- "extended density"), which had a volume of 2880 kilobytes (36 sectors), which did not become widespread.
Disappearing
One of the main problems with floppy disks was their fragility. The most vulnerable element of the floppy disk design was a tin or plastic casing that covered the floppy disk itself: its edges could bend, which led to the floppy disk getting stuck in the disk drive, the spring that returned the casing to its original position could be displaced, as a result, the floppy disk casing was separated from the case and never returned to starting position. The plastic case of the floppy disk itself did not provide sufficient protection for the floppy disk from mechanical damage (for example, when a floppy disk fell on the floor), which rendered the magnetic medium out of order. Dust could have entered the crevices between the diskette case and the shroud.
The massive displacement of floppy disks from everyday life began with the advent of rewritable CDs, and especially flash-based media, which have a much lower unit cost, orders of magnitude greater capacity, higher actual number of rewriting cycles and durability, and higher data exchange rate.
CD-ROM(eng. compact disc read-only memory) is a compact optical disc containing data accessible to a computer. Since the disc was originally intended for storing and playing music, it was later modified to store digital data. CD-ROMs are a popular medium for distributing software, computer games, and multimedia applications. Some CDs contain both computer and audio data that can be played back in a CD player, while computer data (such as software or digital video) is only accessible through a computer. This type of disc is called enhanced discs (eng. Enhanced CD).
Technical details
A compact disc is a 1.2 mm thick polycarbonate substrate covered with the thinnest layer of metal (aluminum, gold, silver, etc.) and a protective layer of varnish, on which a graphical representation of the disc content is usually applied. The principle of reading through a substrate has been adopted, since it makes it possible to very simply and effectively protect the information structure and remove it from the outer surface of the disk. The diameter of the beam on the outer surface of the disk is about 0.7 mm, which increases the noise immunity of the system to dust and scratches. In addition, there is a 0.2 mm high annular protrusion on the outer surface, which allows the disc, placed on a flat surface, not to touch this surface. A hole 15 mm in diameter is located in the center of the disc. The weight of the disc without box is approximately 15.7 g. The weight of the disc in a regular (not "slim") box is approximately 74 grams.
Compact disks are 12 cm in diameter and initially contained up to 650 MB of information. However, starting from about 2000, 700 MB disks began to gain more and more distribution, subsequently completely replacing the 650 MB disk. There are also media with a volume of 800 megabytes or more, but they may not be readable on some CD drives. There are also 8cm discs that hold about 140 or 210 MB of data and CDs shaped like credit cards (called business card discs).
CD-ROM under an electron microscope
Information on the disc is recorded in the form of a spiral track of the so-called pits (recesses), squeezed into a polycarbonate base. Each pit is approximately 100 nm deep and 500 nm wide. The length of the pit varies from 850 nm to 3.5 μm. The intervals between the pits are called the land. The pitch of the tracks in the spiral is 1.6 µm.
There are read-only discs ("aluminum"), CD-R - for write once, CD-RW - for rewritable. Discs of the last two types are intended for recording on special writing drives.
CD-R (Compact Disc-Recordable Compact Disc Recordable) is a type of compact disc (CD) developed by Philips and Sony for write-once information. CD-R supports all the features of the "Red Book" standard, plus it allows you to record data.
Technical details
An ordinary CD-R is a thin disc made of transparent plastic - polycarbonate - 1.2 mm thick, 120 mm in diameter (standard), weight 16-18 g. or 80 mm (mini). The capacity of a standard CD-R is 74 minutes of audio or 650 MB of data. However, at the moment, the standard can be considered a CD-R with a capacity of 702 MB of data (more precisely 736 966 656 bytes) or 79 minutes 59 seconds and 74 frames. This capacity is achieved by slightly exceeding the Orange Book (CD-R / CD-RW) tolerances. There are also 90 minute / 790 MB and 99 minute / 870 MB discs on the market, which are much less common.
The polycarbonate disc has a spiral path for guiding the laser beam when writing and reading information. On the side where this spiral track is located, the disc is covered with a recording layer, which consists of a very thin layer of organic dye and then a reflective layer of silver, its alloy or gold. This reflective layer is coated with a protective photopolymerizable varnish and UV-cured. And already on this protective layer, various ink inscriptions are applied.
A blank CD-R is not completely blank, it has a service track with ATIP servo marks - Absolute Time In Pregroove- absolute time in the service track. This service track is needed for the tracking system, which keeps the laser beam on the track while recording and monitors the recording speed (that is, it makes sure that the length of the pit is constant). In addition to synchronization functions, the service track also contains information about the manufacturer of this disc, information about the material of the recording layer, the length of the recording track, etc. distinguish the original from the copy.
The first companies to release CD-R blanks were Taiyo Yuden, Kodak, Maxell and TDK. Since then, the CD-R standard has undergone further development to provide higher write speeds and currently (2006) the maximum possible CD-R write speed is 52x, that is, 52 times faster than that defined in the Orange Book standard. (1x = 150 KB / s). These improvements consist mainly of new materials for the recording layer, better track geometry and technology for applying the recording layer. Low-speed 1x recording is still used today for recording special "audio CD-R" s, as CD-burner decks were standardized for this very speed.
There are three main types of recording layer for CD-Rs:
1. Cyanine (eng. Cyanine) - Cyanine dye has a blue-green (aqua color) shade of the working surface. This material was used in the earliest "blank" CD-Rs and is patented by Taiyo Yuden. This dye is chemically unstable, which is the reason for the short guaranteed storage life of the recorded information. The dye may take several years to fade. Although many manufacturers use additional chemical additives to increase the stability of cyanine, such drives are not recommended for backup and long-term archival purposes.
2. Azo - Metallized azo dye, has a dark blue color. Its formula is patented by Mitsubishi Chemicals. This dye is chemically stable and its ability to store information is calculated for decades (the companies themselves write about 100 years).
3. Phthalocyanine (eng. Phthalocyanine) - Slightly later development of the active recording layer. Phthalocyanine is practically colorless, with a pale shade of light green or golden, which is why discs based on a phthalocyanine active layer are often called “golden”. Phthalocyanine is a slightly more modern development. Discs based on this active layer are less sensitive to sunlight and ultraviolet radiation, which helps to increase the durability of the recorded information and somewhat more reliable storage in adverse conditions (firms claim hundreds of years).
Unfortunately, many manufacturers use various additives in the recording layer to make cyanine blanks look similar in color to phthalocyanine blanks. Therefore, it is not possible to simply determine the material of the recording layer by color. Likewise, the reflective layer of "gold" color does not guarantee that it is a phthalocyanine CD-R.
CD-RW(eng. Compact Disc-Rewritable, CD-Rewritable) is a type of compact disc (CD) developed in 1997 for rewritable information.
Technical details
CD-RW is a further logical development of the recordable laser CD-R, however, unlike it, it allows multiple rewriting of data. This format was introduced in 1997 and was called CD-Erasable (CD-E) during development. CD-RW is in many ways similar to its predecessor CD-R, but its recording layer is made of a special alloy of chalcogenides, which, when heated above the melting point, changes from a crystalline state of aggregation to an amorphous state. Phase transitions between different states of matter are always accompanied by a change in the physical parameters of the medium. The normal state of solids and the main one in the nature around us is crystalline. In this respect, amorphous bodies are a rarity, since the glassy (amorphous) state is realized only when the supercooled melt solidifies. Glass differs from other amorphous states in that the melt-glass and glass-melt transition processes are reversible. This feature is extremely important for the creation of reversible optical recording media, that is, providing multiple rewriting. The main condition for the formation of glassy states, including metals, is cooling, so fast that the atoms do not have time to occupy their assigned places in the crystal cells and "freeze" at random when the thermal relaxation of the atoms is comparable or becomes less than the interatomic distances. It is not difficult to create conditions for ultrafast cooling with an active layer thickness of an optical disc of 0.1 µm. Full cycle: recording - repeated playback - erasing - new recording looks like this. By heating with a laser, the working layer of the optical disk, which is in the crystalline state, is transferred to the melt. Due to the rapid diffusion of heat into the substrate, the melt is rapidly cooled and passes into the glass phase. The crystalline and glassy states have different dielectric constant, reflectance, and, consequently, the intensity of the reflected light, which carries information about the recording on the disc. The readout is performed at a reduced laser radiation intensity, which does not affect the phase transitions. For a new recording, it is necessary to return the working layer to its original crystalline state. For this, two-stage modulation (a short powerful pulse for melting the active layer and a long pulse for gradual cooling of the substance) of the laser power is used. Overheating will slow down the process of heat diffusion and create conditions for returning to the crystalline phase. The active layer is usually made of chalcogenide glass - an alloy of silver (Ag), indium (In), antimony (Sb) and tellurium (Te).
Multiple rewriting, in principle, can lead to mechanical fatigue of the working layer and, as a consequence, to its destruction. Therefore, when choosing substances, the absence of the effect of fatigue accumulation becomes an important factor. Modern CD-RW discs can rewrite information about 1000 times. Working with CD-RW discs is very similar to working with write-once CD-R discs. Later, a new format for recording CD-RW discs appeared - Universal Disk Format (UDF, Packet Writing), which allows you to "format" a disk and work with it like a regular large floppy disk, which allows reading / writing / deleting / modifying data. The volume of such UDF-formatted disks is approximately 530 MB, as opposed to the usual 700 MB when recording one session to the entire disk.
CD-RW discs do not meet the “Red Book” (CD-ROM) and “Orange Book Part II” (CD-R) reflectance requirements. Therefore, such discs are not readable in older CD-ROM drives made before 1997. CD-R is considered a more suitable standard for backup media, since the information recorded on them can no longer be changed and the manufacturers of "blanks" indicate a longer storage time for CD-R discs than for CD-RW discs.
During normal recording to CD-RW (not UDF), periodically you need to completely erase the disc. There are two types of erasure - "full" and "fast". As the name suggests, with a "complete" erasure, the entire disk is converted to a crystalline state and the old information is physically destroyed. A "quick" erase only clears a small part of the disk (eng. Lead-in- the area where information about the content of the disc is stored), which is much faster. However, there is a technical possibility to recover the data. Therefore, if there is a need to preserve the confidentiality of information, then you need to use full erasure.
DVD(eng. Digital Versatile Disc- digital multipurpose disk; also English. Digital Video Disc- digital video disc) - a storage medium made in the form of a disc, outwardly similar to a compact disc, but having the ability to store a large amount of information due to the use of a laser with a shorter wavelength than for conventional compact discs.
The first discs and DVD players appeared in November 1996 in Japan and in March 1997 in the United States.
In the early 1990s, two standards were being developed for high-density optical media. One of them was called Multimedia Compact Disc (MMCD) and was developed by Philips and Sony, the second - Super Disc- supported by 8 large corporations, including Toshiba and Time Warner. Later, the efforts of the standards developers were united under the leadership of IBM, which did not want a repetition of the bloody war of formats, as was the case with the VHS and BetaMax cassette standards in the 1970s. The DVD was officially announced in September 1995. The first version of the DVD specifications was published in September 1996. The specifications are amended and supplemented by the DVD Forum (formerly the DVD Consortium), of which 10 founding companies and more than 220 individuals are members.
The first drive to support DVD-R recording was released by Pioneer in October 1997. The drive, which supported the DVD-R 1.0 specification, was priced at $ 17,000. 3.95 GB discs were priced at $ 50 each.
Originally, "DVD" stands for "Digital Video Disc", as the format was originally developed as a replacement for videotapes. Later, when it became clear that the medium is also suitable for storing arbitrary information, many began to decrypt DVDs as Digital Versatile Disc (digital multipurpose disc). Toshiba, which runs the DVD Forum's official website, uses Digital Versatile Disc.
Until now, no consensus has been reached, so today “DVD” is not officially deciphered at all.
Technical information
A red laser with a wavelength of 650 nanometers is used to read and write DVDs.
There are four types of data structure DVDs:
· DVD-video - contains movies (video and sound);
· DVD-Audio - contains high quality audio data (much higher than on audio CDs);
· DVD-Data - contain any data;
· Mixed content.
Unlike CDs, in which the structure of an audio disc is fundamentally different from a data disc, DVDs always use the UDF file system (ISO 9660 can be used for data).
Any of the types of DVD media can carry any of the four data structures (see above).
Physically, a DVD can have one or two working sides and one or two working layers on each side. The capacity of the disc depends on their number (which is why they also received the names DVD-5, -9, -10, -14, -18, according to the principle of rounding the disc capacity in GB to the nearest integer from above):
The figures shown are approximate. On DVD, data is recorded in sectors; one sector contains 2048 bytes. Therefore, the exact value of the capacity of a DVD can be determined by multiplying 2048 by the number of sectors on the disc, which varies slightly for different types of DVD media (figures are given for 1-sided discs; for 2-sided, everything is 2 times more):
Note: The DVD-R (W) format does not specify the exact number of sectors, but only requires the capacity to be at least 4.7 billion bytes. However, most manufacturers adhere to the number of 2,298,496 sectors, which is indicated in the table.
The capacity can be determined by eye - you need to look at how many working (reflective) sides the disc has and pay attention to their color: the two-layer sides are usually gold, and the single-layer sides are silver, like a CD.
The unit of speed (1x) for DVD read / write is 1,385,000 bytes / s (that is, about 1352 KB / s = 1.32 MB / s), which roughly corresponds to the 9th speed (9x) of CD read / write, which is nine ? 150 = 1350 KB / s. So a 16-speed drive can read (or write) a DVD at 16? 1.32 = 21.12 MB / s.
DVD ± R formats and compatibility
The DVD-R (W) recording standard was developed in 1997 by the DVD Forum group of companies as the official specification for recordable (subsequently rewritable) discs. However, the license price for this technology was too high, and therefore several manufacturers of recorders and recording media merged into the DVD + RW Alliance, which developed the DVD + R (W) standard in mid-2002, the cost of the license for which was lower. Initially, blanks (blank discs for recording) DVD + R (W) were more expensive than blanks DVD-R (W), but now the prices are equal.
All DVD drives can read both disc formats, and most burners can also burn both types of discs. Among other drives, the + and - formats are equally popular - half of the manufacturers support one standard, half the other. There is debate over whether one of these formats will oust its competitor or whether they will continue to coexist peacefully. However, since the DVD-R (W) format appeared almost 5 years before DVD + R (W), many older or cheaper players are likely to only support DVD-R (W). This should be taken into account, especially when burning discs for distribution when the type of reader (player or DVD drive) is not known in advance.
BD-ROM(eng. blue ray- blue ray and disc- disk) is an optical media format used for recording and storing digital data, including high-definition video with increased density. The Blu-ray standard was jointly developed by the BDA consortium.
Blu-ray (lit. "blue-ray") gets its name from the use of a shortwave (405 nm) "blue" (technically blue-violet) laser to write and read. Presented at the Consumer Electronics Show (CES), January 2006. The commercial launch of the Blu-ray format took place in the spring of 2006.
From its inception in 2006 until early 2008, Blu-ray had a serious competitor - the alternative HD DVD format. Over the course of two years, many of the largest film studios that originally supported HD DVD have gradually moved to Blu-ray. Warner Brothers, the last company to release both formats, phased out HD DVD in January 2008. On February 19 of the same year, Toshiba, the creator of the format, stopped developing HD DVD. This event put an end to the so-called "format war".
Variations and sizes
A single layer Blu-ray Disc (BD) can store 23.3 / 25/27 or 33 GB, a dual layer disc can hold 46.6 / 50/54 or 66 GB. Also in development are disks with a capacity of 100 GB and 200 GB using respectively four and eight layers. TDK Corporation has already announced a prototype of a four-layer disc with a capacity of 100 GB.
BD-R and BD-RE discs are currently available, BD-ROM format is in development. In addition to the standard 120mm discs, there are also 80mm disc options for use in digital still cameras and camcorders. It is planned that their volume will reach 15 GB for a two-layer version
Technical features
Laser and optics
Blu-ray technology uses a 405 nm blue-violet laser for reading and writing. Conventional DVDs and CDs use red and infrared lasers with wavelengths of 650 nm and 780 nm, respectively.
This reduction made it possible to narrow the track in half compared to a conventional DVD (down to 0.32 microns) and increase the data recording density.
The shorter blue-violet laser wavelength allows more information to be stored on 12cm discs the same size as CD / DVD. The effective "spot size" on which the laser can focus is limited by diffraction and depends on the wavelength of the light and the numerical aperture of the lens used to focus it. Reducing the wavelength, using a larger numerical aperture (0.85 versus 0.6 for DVD), a high-quality two-lens system, and a sixfold decrease in the protective layer thickness (0.1 mm instead of 0.6 mm) made it possible to conduct better and more correct flow of read / write operations. This made it possible to write information to smaller points on the disk, which means more information to be stored in the physical area of the disk, as well as to increase the read speed up to 432 Mbps.
According to archaeologists, the desire to record information in humans appeared about forty thousand years ago. The very first carrier was a rock. This stationary data storage had a lot of advantages (reliability, resistance to damage, large capacity, high read speed) and one drawback (laboriousness and slowness of writing). Therefore, over time, more and more advanced information carriers began to appear.
Perforated paper tape
Most early computers used paper tape wound on spools. Information was stored on it in the form of holes. Some machines, such as the Colossus Mark 1 (1944), worked with data that was entered using tape in real time. Later computers, such as the Manchester Mark 1 (1949), read programs from tape and loaded them into a primitive semblance of electronic memory for subsequent execution. Perforated tape has been used to write and read data for thirty years.
Punch cards
The history of punched cards goes back to the very beginning of the 19th century, when they were used to control weaving looms. In 1890, Herman Hollerith used the punch card to process US census data. It was he who found the company (future IBM) that used such cards in their calculating machines.
In the 1950s, IBM was already using punched cards in its computers for storing and entering data with might and main, and soon other manufacturers began to use this medium. Then, 80-column maps were common, in which a separate column was allocated for one symbol. One might be surprised, but in 2002, IBM was still continuing to develop in the field of punch card technology. True, in the 21st century, the company was interested in postage stamp-sized cards capable of storing up to 25 million pages of information.
Magnetic tape
With the release of the first American commercial computer UNIVAC I (1951), the era of magnetic tape began in the IT industry. As usual, IBM again became a pioneer, then others "pulled up". The magnetic tape was wound in an open way on spools and was a very thin strip of plastic coated with a magnetically sensitive substance.
The machines recorded and read data using special magnetic heads built into the reel drive. Magnetic tape was widely used in many models of computers (especially mainframes and minicomputers) until the 1980s, when tape cartridges were invented.
First removable drives
In 1963, IBM introduced the first removable disk drive, the IBM 1311. It was a set of interchangeable disks. Each set consisted of six 14-inch disks containing up to 2 MB of information. In the 1970s, many hard drives, such as the DEC RK05, supported such disk sets, especially minicomputer manufacturers used them to sell software.
Ribbon cartridges
In the 1960s, computer hardware makers learned to fit rolls of magnetic tape into miniature plastic cartridges. They differed from their predecessors, bobbins, with a long lifespan, portability and convenience. They became most widespread in the 1970s and 1980s. Like spools, cartridges proved to be very flexible media: if there was a lot of information to be recorded, more tape would simply fit into the cartridge.
Today, tape cartridges such as the 800GB LTO Ultrium are used for large-scale server support, although their popularity has declined in recent years due to the greater convenience of transferring data from hard drive to hard drive.
Printing on paper
In the 1970s, personal computers were gaining popularity due to their relatively low cost. However, the existing ways of storing data turned out to be beyond the means of many. One of the first PCs, MITS Altair, was delivered without any storage media at all. Users were prompted to enter programs using special toggle switches on the front panel. Then, at the dawn of the development of personal computers, users often had to literally insert sheets with
handwritten programs. Later, the programs began to be distributed in print through paper magazines.
Floppy disks
In 1971, the first IBM floppy disk appeared. It was an 8-inch floppy disk covered with a magnetic substance, enclosed in a plastic case. Users quickly realized that floppy disks were faster, cheaper, and more compact than stacks of punched cards to download data to a computer. In 1976, one of the creators of the first floppy disk, Alan Shugart, proposed a new 5.25-inch format. This size lasted until the late 1980s, when Sony 3.5-inch floppy disks appeared. How it started ...
In the late 60s, the American firm IBM proposed a new storage device that used a floppy disk (floppydisk). A floppy disk works in the same way as a hard disk, but is made in the form of an elastic round plate with a plastic base coated with a magnetic compound. The disc is placed in a special flexible envelope-cassette, which protects it from mechanical damage and dust.
The disk with the envelope is installed by the user into a special device (disk drive). In this device, it rotates inside the envelope at a speed of about 300 rpm.
To reduce friction, the inside of the envelope is covered with a special material. Through specially made slots, the magnetic read-write head of the drive contacts the surface of the disc and reads or writes the corresponding information. A floppy disk drive (floppy disk drive) is a complex mechanical device that requires a special electronic controller unit to be connected to a computer, which converts the commands from the machine to the drive, and monitors their execution, and also controls the data exchange process.
IBM has proposed the use of 203 mm (8 Imp.) Floppy disks and has developed a standard for these disk drives.
The new external memory device began to gain in popularity. In 1976, about 200 thousand devices were sold, in 1981 already 3-4 million, for a total of $ 2.3 billion, and in 1984 8.2 million were delivered. NGMD in the amount of 4.2 billion dollars.In the United States alone in 1984 for NGMD 285 million floppy disks were manufactured.
Along with the rapid development of computer technology, NGMD... In the early 1970s, American inventor Alain Shugart proposed reducing the disc diameter to 133 mm (5.25 inches). In 1976, the Shugart Associates company, which he founded, released the first floppy disk drives of this size, called minidisks (minifloppy). Despite initially having less external memory, these drives were half the price of standard drives with 203mm drives. The latter circumstance immediately attracted the attention of a wide group of PC users to them.
Improving the quality of recording and the quality of magnetic heads allowed the transition to floppy disks with a double recording density.
The first 203mm and 133mm floppy discs used only one side of the disc. In order to increase the volume of external storage devices were developed and began to be supplied in which information was written and read from both sides of the disk. This increased the memory capacity by 2 times, and taking into account the double recording density - 4 times.
Development and production NGMD engaged in several dozen firms in the USA, Japan, Germany and other countries. These devices have quickly supplanted tape drives in many PC applications. Usage NGMD increased the speed of the system by an order of magnitude.
Nowadays, external memory on floppy disks has become an integral part of the typical configuration of most educational and all professional PCs.
In what directions was further technical development NGMD ?
First, the physical dimensions of storage rings continued to decrease, in particular, in height. Many firms produced half-height drives, that is, two devices could already be accommodated in the previous case.
Secondly, successful attempts were made to reduce the diameter of the disks, and, consequently, the dimensions of the drive. Thus, the Japanese company Sony developed NGMD with 89 mm (3.5 in) discs. The disc is housed in a 90x94 mm (3.54x3.7 inches) and 1.3 mm thick hard envelope equipped with a special metal shutter. When the disc is inserted into the drive, the shutter automatically slides to reveal a slot in the envelope through which the magnetic head interacts with the floppy disc. With a double recording density, such a single-sided disc holds 360 KB, and with double-sided recording, 720 KB.
A standard Sony drive cost about 10% more than a drive on 133-mm disks, and 89-mm disks themselves were 2-2.5 times more expensive than similar 133-mm disks. However, the small size of the disks and the drive itself, the rigid design of the envelope with the disk and the protection of the disk surface with a "curtain" attracted this type NGMD a significant number of users. Drives with 89-mm disks with a volume of 720 KB have found application in many portable PCs, for example, in the models of the Japanese company "Toshiba" - T1100, T1200, T3100, the American firms "Zenith Data Systems" - Z181, "Bondwell Inc." - Bondwell 8 and others. IBM in the PS / 2 series PC models uses NGMD with discs with a diameter of 89 mm, 720 KB and 1.44 MB.
Thirdly, due to the use of new technical means and technologies, a number of firms have developed NGMD with increased memory capacity.
For example, the IBM company in PC AT used drives on 133-mm disks with a volume of 1.2 MB of formatted memory. Due to the transition to a higher density of tracks on the disk, it was possible to more than double the volume of external PC storage.
Japanese firm Hitachi-Maxwell announced the development of 133mm floppy disks with 19MB of memory per disk. In a short time, the volume of 89-mm disks has grown from 360 KB to 1.44 MB.
By the beginning of 1987, the most common in the world were 133-mm disks for PCs from IBM, and drives on disks with a diameter of 203 mm had practically ceased to be produced. The 89mm market is growing very quickly NGMD.
According to the estimates of the company "DateAquest" (USA), the production of 133-mm drives grew from 8.2 million units in 1985 to 11 million units in 1987, and then fell by 1991 to 7.3 million units. ... At the same time, the production of 89-mm drives increased from 603 thousand units in 1985 to 14 million units in 1991, i.e., by the end of the 1980s, it exceeded the production of 133-mm drives.
A standard drive for an IBM PC with 360KB 133mm drives was $ 65 in the US in mid-1987, and $ 150 for a 720K 89mm drive.
Compact cassettes
The compact cassette was invented by Philips, who guessed to fit two small rolls of magnetic tape into a plastic case. It was in this format that audio recordings were made in the 1960s. HP used such cassettes in its HP 9830 desktop (1972), but in the beginning such cassettes were not very popular as digital media. Then the seekers of inexpensive data carriers nevertheless turned their eyes towards cassettes, which, with their light hand, remained in demand until the early 1980s. data on them, by the way, could be loaded from a regular audio player.
Since the introduction of the first magnetic storage device (IBM RAMAC), surface recording densities have grown by 25% per year, and 60% since the early 1990s. The development and implementation of magnetoresistive (1991) and giant magnetoresistive (1997) heads further accelerated the increase in surface recording density. In the 45 years since the first magnetic storage devices were introduced, areal recording densities have grown more than 5 million times.
In modern 3.5-inch drives, this parameter is 10-20 Gb / in 2, and in experimental models it reaches 40 Gb / in 2. This allows the production of drives with a capacity of more than 400 GB.
ROM cartridges
A ROM cartridge is a board that consists of a read-only memory (ROM) and a connector that are housed in a hard shell. Scope of cartridges - computer games and programs. For example, in 1976 the Fairchild company released a ROM-cartridge for recording software for the Fairchild Channel F video set-top box. Soon, home computers such as Atari 800 (1979) or TI-99/4 (1979) were adapted to use ROM cartridges.
ROM cartridges were easy to use, but relatively expensive, which is why, in fact, they "died".
Great experiments with floppy disks
In the 1980s, many companies tried to create alternatives to the 3.5-inch floppy disk. One such invention (pictured above in the center) can hardly be called a floppy disk even at a stretch: the ZX Microdrive cartridge consisted of a huge roll of magnetic tape, like an eight-track cassette. Another experimenter, Apple, created a FileWare floppy disk (right) that came with the first Apple Lisa computer, the worst device in the company's history according to Network World, as well as a 3-inch Compact Disk (bottom left) and a now-rare 2-inch floppy disk.
LT-1 (top left) used exclusively in the 1989 Zenith Minisport laptop. The rest of the experimentation culminated in products that became niche and failed to replicate the success of their 5.25-inch and 3.5-inch predecessors.
Optical disc
Originally used as a digital audio medium, the compact disc owes its birth to a collaboration between Sony and Philips and first appeared on the market in 1982. Digital data is stored on this plastic carrier in the form of micro-grooves on its mirror surface, and the information is read using a laser head.
As it turned out, digital CDs are the best suited for storing computer data, and soon the same Sony and Philips finalized the novelty.
This is how the world learned about CD-ROMs in 1985.
Over the next 25 years, the optical disc has undergone many changes, its evolutionary chain includes DVD, HD-DVD and Blu-ray. A significant milestone was the introduction in 1988 of the CD-Recordable (CD-R), which allowed users to independently record data to disc. In the late 1990s, optical discs finally fell in price and finally relegated floppy disks to the background.
Magneto-optical media
Like CDs, magneto-optical discs are "read" by a laser. However, unlike conventional CDs and CD-Rs, most magneto-optical media can be printed and erased multiple times. This is achieved through the interaction of a magnetic process and a laser when recording data. The first magneto-optical disk was included with the NeXT computer (1988, photo on the bottom right), and its capacity was 256 MB. The most famous media of this type is Sony's MiniDisc (top center, 1992). He also had a "brother" for storing digital data, which was called MD-DATA (top left). Magneto-optical disks are still in production, but due to their low capacity and relatively high cost, they have become a niche product.
Iomega and Zip Drive
Iomega made its mark in the media market in the 1980s with the Bernoulli Box magnetic disk cartridges ranging from 10 to 20 MB.
A later interpretation of this technology was embodied in the so-called Zip media (1994), which contained up to 100 MB of information on an inexpensive 3.5-inch disk. The format fell in love with its affordable price and good capacity, and Zip drives remained on the rise in popularity until the late 1990s. However, the CD-Rs already available at that time could be written up to 650 MB, and when their price dropped to a few cents apiece, sales of Zip disks plummeted. Iomega made an attempt to save the technology and developed discs in sizes of 250 and 750 MB, but by that time CD-R had already conquered the market. This is how Zip became history.
Floppy disks
The first superdisk was released by Insight Peripherals in 1992. The 3.5-inch disk contained 21 MB of information. Unlike other media, this format was compatible with earlier traditional 3.5-inch floppy disk drives. The secret of the high efficiency of such drives lay in the combination of a floppy disk and optics, that is, data was recorded in a magnetic medium using a laser head, while more accurate recording and more tracks, respectively, more space were provided. In the late 1990s, two new formats appeared - Imation LS-120 SuperDisk (120 MB, bottom right) and Sony HiFD (150 MB, top right). The novelties became serious competitors to the Iomega Zip drive, but in the end the CD-R format won out.
The mess in the world of portable media
The resounding success of the Zip Drive in the mid-1990s spawned a slew of similar devices, whose manufacturers hoped to grab a piece of the market from the Zip. Among the main competitors of Iomega is SyQuest, which first shattered its own market segment, and then ruined its product line with excessive variety - SyJet, SparQ, EZFlyer and EZ135. Another serious, but "murky" rival is Castlewood Orb, which invented a disk like the Zip with a capacity of 2.2 GB.
Finally, Iomega itself has made an attempt to complement the Zip drive with other types of removable media - from large removable hard drives (1 and 2 GB Jaz Drives) to a miniature 40 MB Clik drive. But none has reached the heights of the Zip.
Flash is coming
In the early 1980s, Toshiba invented NAND flash memory, but the technology did not become popular until a decade later, following the advent of digital cameras and PDAs. At this time, it began to be sold in different forms - from large credit cards (intended for use in early handhelds) to CompactFlash cards, SmartMedia, Secure Digital, Memory Stick and xD Picture Cards.
Flash memory cards are convenient, first of all, because they have no moving parts. In addition, they are economical, durable and relatively inexpensive with ever-increasing storage capacity. The first CF cards held 2 MB, but now their capacity reaches 128 GB.
Much less
The IBM / Hitachi promo slide shows a tiny Microdrive. It appeared in 2003 and for some time won the hearts of computer users.
The iPod and other media players, which debuted in 2001, are equipped with similar devices based on a rotating disk, but manufacturers quickly became disillusioned with such a drive: it is too fragile, power-intensive and small in volume. So this format is almost buried.
1956 - IBM 350 hard drive as part of the first production computer IBM 305 RAMAC. The drive occupied a box the size of a large refrigerator and weighed 971 kg, and the total memory capacity of the 50 thin discs covered with pure iron with a diameter of 610 mm rotating in it was about 5 million 6-bit bytes (3.5 MB in terms of 8-bit bytes) ...
And here's what concerns hard drives.
* 1980 - First 5.25-inch Winchester, Shugart ST-506, 5 MB.
* 1981 - 5.25-inch Shugart ST-412, 10 MB.
* 1986 - SCSI, ATA (IDE) standards.
* 1991 - maximum capacity 100 MB.
* 1995 - maximum capacity 2 GB.
* 1997 - Maximum capacity 10 GB.
* 1998 - UDMA / 33 and ATAPI standards.
* 1999 - IBM releases 170 MB and 340 MB Microdrive.
* 2002 - ATA / ATAPI-6 standard and drives with capacities over 137 GB.
* 2003 - the appearance of SATA.
* 2005 - maximum capacity 500 GB.
* 2005 - Serial ATA 3G (or SATA II) standard.
* 2005 - the appearance of SAS (Serial Attached SCSI).
* 2006 - Application of the perpendicular recording method in commercial drives.
* 2006 - the appearance of the first "hybrid" hard drives containing a block of flash memory.
* 2007 - Hitachi introduces the first commercial 1TB drive.
* 2009 - based on Western Digital 500 GB platters, then Seagate Technology LLC released 2 TB models.
* 2009 - Western Digital announced the creation of a 2.5-inch HDD with a volume of 1 TB (recording density - 333 GB on one platter)
* 2009 - the appearance of the SATA 3.0 (SATA 6G) standard.
The advent of USB
In 1998, the USB era began. The undeniable convenience of USB devices has made them almost an integral part of the life of all PC users. Over the years, they decrease in physical size, but become more capacious and cheaper. Especially popular appeared in 2000 "flash drives", or USB thumb drives (from the English thumb - "thumb"), so named for their size - the size of a human finger. Due to their large capacity and small size, USB drives have become perhaps the best storage medium invented by mankind.
Transition to virtuality
Over the past fifteen years, local area networks and the Internet have gradually replaced portable storage media from the life of PC users. Since today almost any computer has access to the global network, users rarely need to transfer data to external devices or rewrite to another computer. Nowadays, wires and electronic signals are responsible for the transfer of information. Bluetooth and Wi-Fi wireless standards make physical computer connections unnecessary.
For long-term storage of information in a computer, removable media are widely used, which are optical disks, flash memory, an external hard drive.
Optical discs
Data can be stored on optical CDs (Compact Disc) with a capacity of up to 700 MB and DVDs (Digital Versatile Disc), with a capacity of up to 4.7 GB for single-layer discs (SL - Single Layer) and 7.9 GB for double layers (DL - Double Layer).
In turn, optical discs are divided into disposable, which can be recorded only once - CD-R (or DVD-R) discs, and reusable, rewritable - CD-RW (or DVD-RW) discs.
In computer jargon, blank discs without recording are called "blanks", and the process of recording "burning". To read and write discs, there is a special device called CD-ROM drive - DVD-ROM, which is installed in, the output tray of the device comes out on the front panel of the system unit. DVD-ROM is a versatile device that can both read and write discs in both formats (CD and DVD). In order to place the disc into the drive, you need to press the button on its panel, the tray will come out of the drive, on which you need to put the disc with the shiny side down. Then press the button again or easily push the tray itself so that it closes.
Flash memory
Flash memory (USB Flash drive). Now even the most distant person from computers has probably heard the word. This is flash memory. Today, the flash drive is rapidly replacing optical discs due to ease of use, memory capacity, write and read speed.
At the time of this writing, there are flash drives for sale with a volume of 4 GB to 128 GB. The larger the capacity, the more expensive the flash drive is. In addition, flash drives have different read and write speeds, but in any case, they are several times higher than that of optical disks.
To connect a flash drive to a computer, you just need to insert it into the USB (YUSB) connector (port) on the front or rear panel of the system unit.
Memory cards, familiar to us as storage media in smartphones and digital cameras, also refer to flash memory and can serve as removable media in a computer. In this case, data reading and writing is performed by a card reader, which can be built into the system unit or connected to it via a USB port. The capacity of memory cards varies from 4 GB to 128 GB.
Graduation writing assignment
Exam paper
Issued to a student of group 35 Romanov Andrey Alekseevich
Profession: "Master in Digital Information Processing"
Topic: "Writing information to removable media"
I. Descriptive part
Introduction.
1. Basic terms and concepts
2. Review of information carriers, their advantages and disadvantages, operating principles, characteristics.
4. Selecting a program for recording information on the media
Conclusion.
Bibliography.
Applications.
II. Practical task
1. Create instructions for recording information on the selected removable media
2. Create a test for work
3. Create a presentation on work
The task was given by the master p / o O.S. Crack
Student A.A. Romanov
Ministry of Education and Science of the Udmurt Republic
Autonomous vocational educational institution
Udmurt Republic
"College of Radio Electronics and Information Technologies"
Final written qualification work
by profession "Master in digital information processing"
student of group number 35
Theme : "Writing information to removable media"
Izhevsk, 2015
Introduction
Information carrier(information carrier) - any material object or environment containing (carrying) information, capable of storing the information entered into / on it for a sufficiently long time in its structure. Initially, the amount of information that could fit on the media was small (from 128 MB to 5.2 GB). Gradually, much more information began to fit on the media (up to 3TBt).
Main storage media: floppy disk drives (floppy disks), hard disk drives (hard drives), CD, DVD (including about Blu-ray), flash-memory (flash drives, memory cards).
CDs and DVDs have become part of our life. It is difficult to imagine where we would have stored gigabytes of music, movies and photographs if someone had not invented these round plates with a mirror surface.
At the moment, this topic is relevant, because a modern person is not able to live without information. But information has such a peculiarity - it must be stored somewhere. There are quite a few information storage systems now. It can be stored on magnetic media, and can be stored on optical and magneto-optical media. But a person in our time also faces a rather important problem - the transfer of information from one place to another, as well as an equally important problem of storing information, and, as a consequence, the reliability of media. That is why information storage technologies have developed so rapidly.
The purpose of this final qualifying written work is:
1. Create instructions for recording information on the selected removable media.
Based on this goal, the following tasks have been set:
1. Make an overview of removable media, identify their advantages and disadvantages
2. Select a program for writing to removable media
Basic terms and definitions
Information- information perceived by a person or special devices as a reflection of the facts of the material world in the process of communication.
Recording information is a method of recording information on a material medium.
Removable storage media- information carrier intended for its autonomous storage and use independent of the place of recording.
Media overview
Floppy disk drive (floppy disk media) or floppy disk(English Floppy Disk Drive) is a portable storage medium used for multiple recording and storage of data, which is a flexible magnetic disk placed in a protective plastic case (a 3.5 ″ disk has a more hard case than a 5.25 ″ disk, while the 8 ″ disc is enclosed in a very flexible case) covered with a ferromagnetic layer. Floppy disks usually have a write protection feature, through which you can provide read-only access to data. Floppy disks were widespread from the 1970s to the late 1990s, giving way to more capacious and convenient CDs and flash drives at the beginning of the 21st century.
Dignity:
1. Huge recording density with small media sizes.
2. Low power consumption compared to similar high-capacity media.
3. High reliability and stable performance.
disadvantages:
1. Small capacity for recording (in fact, you cannot record even one song on a disc).
2. Unreliable storage of information, the diskette is demagnetized under the influence of large magnetic fields.
HDD (Hard Disk Media) or Winchester or Hard Disk(English HDD - Hard Disc Drive) is a data storage device based on the principle of magnetic recording. It is the main data storage device in most computers. It is combined with a drive, a drive and an electronics unit and (in personal computers in the overwhelming majority of cases) is usually installed inside the computer's system unit, but it can also be connected from the outside.
Information is recorded on rigid (aluminum or glass) plates covered with a layer of ferromagnetic material, most often chromium dioxide. The HDD uses one or more plates on one axis. The readheads in the operating mode do not touch the surface of the plates due to the interlayer of the incoming air flow formed at the surface during rapid rotation. The distance between the head and the disc is several nanometers (in modern discs about 10 nm), and the absence of mechanical contact ensures a long service life of the device. In the absence of rotation of the disks, the heads are located at the spindle or outside the disk in a safe zone, where their abnormal contact with the surface of the disks is excluded.
The principle of operation of hard drives is similar to the operation of tape recorders. The working surface of the disk moves relative to the reading head (for example, in the form of an inductor with a gap in the magnetic circuit). When an alternating electric current is applied (during recording) to the head coil, the resulting alternating magnetic field from the head gap acts on the ferromagnet of the disk surface and changes the direction of the domain magnetization vector depending on the magnitude of the signal. During reading, the movement of domains at the head gap leads to a change in the magnetic flux in the magnetic circuit of the head, which leads to the appearance of an alternating electric signal in the coil due to the effect of electromagnetic induction.
Recently, a magnetoresistive effect has been used for reading, and magnetoresistive heads have been used in disks. In them, a change in the magnetic field leads to a change in resistance, depending on the change in the strength of the magnetic field. Such heads make it possible to increase the probability of information reading reliability (especially at high information recording densities).
Dignity:
1. Allow you to write and read information many times.
2. When you turn off the computer, the information left on the hard drive is saved.
3. Large amount of stored information.
4. High reliability of data storage. MTBF is about 300,000 hours, i.e. about 30 years.
Disadvantages:
1. Impossibility of carrying it, as it is permanently attached to the system unit.
2. Relatively low performance, especially compared to RAM.
Recording methods
At the moment there are several recording methods:
· Method of longitudinal recording.
· Method of perpendicular recording.
· Thermal magnetic recording method.
CD or CD(English Compact Disc) is an optical storage medium in the form of a plastic disk with a hole in the center, the process of recording and reading information of which is carried out using a laser. DVDs became the further development of CDs (about them a little later).
Initially, a CD was created for storing audio recordings in digital form, but later it became widely used as a medium for storing any data in binary form.
CD-ROM(English Compact Disc Read-Only Memory, read: "sidir") - a kind of compact discs with read-only data recorded on them (read-only memory). CD-ROM is a modified version of CD-DA (disk for storing audio recordings), which allows storing other digital data on it (physically, it is no different from the first, only the format of the recorded data has been changed). Later, versions were developed with the ability to write once (CD-R) and rewrite (CD-RW) information onto a disc. A further development of CD-ROMs were DVD-ROMs.
CD-ROMs- the popular and cheapest tool for distributing software, computer games, multimedia and other data. CD-ROM (and later DVD-ROM) became the main medium for transferring information between computers, replacing the floppy disk from this role (now it gives way to more promising solid-state media).
The CD-ROM recording format also provides for the recording of mixed content information on one disc - simultaneously both computer data (files, software, reading is available only on a computer) and audio recordings (played on a regular audio CD player), video, texts and pictures. Such discs, depending on the order of the data, are called Enhanced CDs or Mixed-Mode CDs.
CD-R(Compact Disc-Recordable) is a type of compact disc (CD) developed by Philips and Sony for recording information once. CD-R supports all the features of the "Red Book" standard, plus it allows you to record data.
A regular CD-R is a thin transparent plastic (polycarbonate) disc 1.2mm thick, 120mm in diameter (standard), weight 16-18g. or 80mm (mini). The capacity of a standard CD-R is 74 minutes of audio or 650MB of data. However, at the moment the standard CD-R capacity can be considered 702MB of data or 79 minutes 59 seconds and 74 frames.
The polycarbonate disc has a spiral path for guiding the laser beam when writing and reading information. On the side with a spiral track, the disc is covered with a recording layer consisting of a very thin layer of organic dye, then a reflective layer of silver, its alloy or gold. This layer is already covered with a protective photopolymerizable varnish and cured with ultraviolet radiation. And already on this protective layer, various ink inscriptions are applied.
A CD-R always has a slug track with ATIP servo marks - Absolute Time In Pregroove - the absolute time in the slug track. This service track is needed for the tracking system, which keeps the laser beam during recording on the track and monitors the recording speed. In addition to synchronization functions, the service track also contains information about the manufacturer of the disc, information about the material of the recording layer, the length of the recording track, etc. The service track is not destroyed when data is written to a disc, and many copy protection systems use it to to distinguish the original from the copy.
CD-RW(English Compact Disc-ReWritable, Rewritable CD) - a kind of compact disc (CD), developed in 1997 for rewritable information
CD-RW is a logical development of CD-R, however, unlike it, it allows multiple rewriting of data. This format was introduced in 1997 and was called CD-Erasable (CD-E) during development. CD-RW is in many ways similar to CD-R, but its recording layer is made of a special alloy of chalcogenides, which, when heated above the melting point, changes from a crystalline state of aggregation to an amorphous state.
DVD(English Digital Versatile (Video) Disc - digital multipurpose (video) disc) is a storage medium made in the form of a disc having the size of a CD, but with a denser structure of the working surface, which allows you to store and read a larger amount of information for by using a laser with a shorter wavelength and a lens with a larger numerical aperture.
The first discs and DVD players appeared in November 1996 in Japan and in March 1997 in the United States.
In the early 1990s, two standards were being developed for high-density optical media. One of them was called Multimedia Compact Disc (MMCD) and was developed by Philips and Sony, the second - Super Disc - was supported by 8 large corporations, including Toshiba and Time Warner. Later, the efforts of the standards developers were united under the leadership of IBM, which did not want a repetition of the format war, as was the case with the VHS and Betamax cassette standards in the 1970s. The DVD was officially announced in September 1995, when the first version of the DVD specifications was published. The specifications are amended and supplemented by the DVD Forum (formerly the DVD Consortium), of which 10 founding companies and more than 220 individuals are members.
The DVD-R (W) recording standard was developed in 1997 by the Japanese company Pioneer and a group of companies that joined it and entered the DVD Forum as the official specification of recordable (subsequently and rewritable) discs.
DVD-RW discs created on the basis of DVD-R initially had a problem associated with the incompatibility of old drives with these new discs (the problem was the difference in the optical layer responsible for "storing" information, which had less (in comparison with write-once and stamped discs) reflectivity). In the future, this problem was almost completely solved, although earlier it was because of this that old DVD drives could not play new rewritable discs normally.
The created alternative format, called DVD + R and which had a different material of the reflective layer and special markings that facilitate positioning of the head - the main difference between such "plus" discs from "minus" ones. With this, DVD + RW discs are able to record in several steps (over the existing one), as in a conventional VCR, eliminating the tedious pre-erasing of the entire content (for DVD-RWs, you must first erase the entire existing recording).
In addition, when using rewritable "plus" disks, the number of errors decreases and the correctness of the write increases, as a result of which the bad sector can be easily overwritten, rather than erasing or rewriting the entire disc. Therefore, if you intend to actively use the function of rewriting and recording, it is better to choose a recorder that supports the "plus" format (which most models are now capable of).
DVD-Video
To play DVD with video, you need a DVD optical drive and an MPEG-2 decoder (that is, either a consumer DVD player with a hardware decoder, or a computer DVD drive and software player with a decoder installed). DVD movies are compressed using the MPEG-2 algorithm for video and various (often multichannel) formats for audio. Compressed video bitrate ranges from 2000 to 9800 Kbps, often variable (VBR). The standard video frame size of the PAL standard is 720 × 576 pixels, the NTSC standard is 720 × 480 pixels.
The audio data in a DVD movie can be PCM, DTS, MPEG, or Dolby Digital (AC-3). In countries using the NTSC standard, all DVD movies must contain a PCM or AC-3 soundtrack, and all NTSC players must support these formats. Thus, any standard disc can be played on any standard equipment.
Blu-ray Disc, BD(English blue ray - blue ray and disc - disc; writing blu instead of blue - intentional) is an optical media format used for recording with increased density and storing digital data, including high-definition video. The Blu-ray standard was jointly developed by the BDA consortium. The first prototype of the new carrier was presented in October 2000. The modern version is presented at the International Consumer Electronics Show (CES), which was held in January 2006. The commercial launch of the Blu-ray format took place in the spring of 2006.
Blu-ray gets its name from its use for writing and reading a shortwave (405 nm) "blue" (technically blue-violet) laser. The letter "e" has been deliberately removed from the word "blue" in order to be able to register a trademark, as the expression "blue ray" is often used and cannot be registered as a trademark.
From its inception in 2006 until early 2008, Blu-ray had a serious competitor - the alternative HD DVD format. Within two years, many of the largest film studios that originally supported HD DVD have gradually moved to Blu-ray. Warner Brothers, the last company to release both formats, phased out HD DVD in January 2008. On February 19 of the same year, Toshiba, the creator of the format, stopped developing HD DVD.
Flash-memory
Flash memory(English flash memory) is a kind of solid-state semiconductor non-volatile rewritable memory (EPROM).
It can be read as many times as you want (within the data storage period, typically 10–100 years), but you can write to such memory only a limited number of times (maximum - about a million cycles). Flash memory is widespread, withstanding about 100 thousand rewriting cycles, much more than a floppy disk or CD-RW can withstand. Contains no moving parts, so, unlike hard drives, it is more reliable and compact.
Due to its compactness, low cost and low power consumption, flash memory is widely used in digital portable devices - cameras and camcorders, voice recorders, MP3 players, PDAs, mobile phones, as well as smartphones and communicators. In addition, it is used to store firmware in various devices (routers, mini-automatic telephone exchanges, printers, scanners, modemax), various controllers. Also recently, USB flash drives ("flash drive", USB-drive, USB-disk) have become widespread, practically replacing floppy disks and CDs.
At the end of 2008, the main drawback preventing flash-based devices from ousting hard drives from the market is the high price / volume ratio, which is 2-3 times higher than that of hard drives. In this regard, the volumes of flash drives are not so great, but work is underway in these areas. The technological process becomes cheaper, competition intensifies. Many companies have already announced the release of SSD-drives with a volume of 256 GB or more.
This type of flash memory is based on an OR-NOT element (English NOR), because in a floating gate transistor, a low gate voltage denotes one.
The transistor has two gates: control and floating. The latter is completely isolated and can hold electrons for up to 10 years. The cell also contains a drain and a source. When programming with voltage, an electric field is created at the control gate and a tunnel effect occurs. Some of the electrons tunnel through the insulator layer and hit the floating gate. The floating gate charge changes the "width" of the drain-source channel and its conductivity, which is used for reading.
Programming and reading cells differ greatly in power consumption: flash memory devices consume a fairly large current when writing, while when reading, power consumption is low.
To erase information, a high negative voltage is applied to the control gate, and electrons from the floating gate pass (tunnel) to the source.
In NOR architecture, each transistor must be connected to an individual contact, which increases the size of the circuit. This problem is solved using the NAND architecture.
The NAND-type is based on a NAND element. The principle of operation is the same, it differs from the NOR-type only in the placement of cells and their contacts. As a result, it is no longer necessary to connect an individual contact to each cell, so the size and cost of a NAND chip can be significantly less. Also writing and erasing is faster. However, this architecture does not allow access to an arbitrary cell.
NAND and NOR architectures now exist in parallel and do not compete with each other, since they are used in different areas of data storage.
Types of memory cards
· CF(Compact Flash)
· MMC(Multimedia Card)
· RS-MMC(Reduced Size Multimedia Card)
· DV-RS-MMC(Dual Voltage Reduced Size Multimedia Card)
· MMC-micro
· SD Card(Secure Digital Card)
· SDHC(SD High Capacity, SD High Capacity)
· MiniSD(Mini Secure Digital Card)
· MicroSD(Micro Secure Digital Card)
© 2015-2019 site
All rights belong to their authors. This site does not claim authorship, but provides free use.
Date the page was created: 2016-04-11
Since when the computer is turned off, all information from the RAM disappears, we need a device that could store all our programs and personal information, regardless of whether the computer is turned on or not.
Such a device is a hard disk (HDD, Hard Drive Disk). In colloquial speech, you can also hear the name "Winchester" or "screw". The hard drive, like all other devices, is located inside the system unit in a special compartment where it is fastened with screws. The hard drive is connected to the motherboard with a special cable called a ribbon cable. There are two main connectors on the motherboard for connecting hard drives. More precisely, there are three of them, but one is rarely used in home computers.
Modern motherboards no longer have outdated IDE (Integrated Drive Electronics) connectors, but your computer may well have these connectors. Currently, the SATA (Serial Advanced Technology Attachment) connector is widely used. Don't be intimidated by these scary acronyms. This is just a designation of the type of connector, that is, simply speaking, the "socket" into which the "plug" is stuck.
If you decide to replace your computer's hard drive with a larger one, then you need to know what type of connector is used on your motherboard. You can take the whole system unit with you to the store, and the sales consultant will pick up hard drive options on the spot. Or there is a simpler option - take only a book from the motherboard with you. It will describe all the connectors, including those for connecting hard drives, and it will not be difficult for a sales consultant to choose a hard drive for you.
The volume of hard disks, like RAM, is measured in bytes, more precisely in megabytes and terabytes. All your information is stored on the hard drive. These are your photos, movies, music and text documents. Programs and the Windows operating system are also stored as files and folders on your hard drive.
In addition to hard drives, information can be stored for a long time on so-called removable media. From the name it is clear that using removable media you can transfer information from one computer to another. The hard drive in your computer is installed inside the system unit. Although it can be removed, it is still considered a non-removable media. But various flash drives or external hard drives connected via the USB connector (we'll talk about the connector a little later) belong to this class of devices.
Flash drives- This is probably the most popular type of removable media at the present time, but it is still too early to write off CDs.
01.11.2012
