Understanding Hard Drives, DVDs, and Other Storage Devices

Posted on Nov 17, 2024 in Technology

Disclaimer: This document is based on the MME Item 4 McGraw-Hill book, formatted for easier conversion to JAR format and use on mobile devices.

Mass Storage Devices

Modern computers typically include a hard disk drive (HDD) and a DVD rewritable drive. Floppy drives are becoming obsolete. Many computers now feature card readers for connecting portable storage devices like CompactFlash, SmartMedia, and Secure Digital cards.

Hard Disk Drives (HDD)

HDDs store a computer’s critical information. They are part of the secondary memory, offering large, non-volatile storage. However, access is slower than main memory (RAM).

Physical Structure

A hard drive is a sealed box containing:

  • Platters: Store information magnetically.
  • Read/write heads: Access the data on the platters.
  • Head arm: Moves the read/write heads.
  • Motor: Spins the platters.

Operation

Data is stored on magnetic platters with read/write heads. The platters spin constantly while the computer is on. The heads move to access information.

Data Organization

Data is organized using:

  • Heads: Read/write elements, one for each data surface.
  • Cylinders: All tracks at a specific head position.
  • Sectors: Smallest units of information that can be read or written.

Addressing Methods

  • CHS (Cylinder, Head, Sector): Older method with limitations.
  • LBA (Logical Block Addressing): Modern method for larger drives.

Logical Structure

  • Boot sector: Contains the partition table and boot program.
  • Partitions: Logical divisions of the hard disk.
  • Unpartitioned space: Space not assigned to a partition.

Performance Factors

  • Storage capacity
  • Transfer mode (PIO, DMA, UltraDMA)
  • Access time
  • Seek time
  • Rotational speed
  • Latency
  • Disk cache
  • Interface (ATA/IDE, SATA, SCSI, USB, Firewire, eSATA)
  • Size
  • Noise
  • Operating temperature
  • Shock and vibration tolerance
  • Price

ATA/IDE (PATA) and SATA

ATA/IDE (also known as IDE or PATA) was the most common interface. SATA is the newer standard, offering faster transfer rates and simpler cabling.

SCSI

SCSI hard drives are used in professional environments for high performance and reliability.

External Hard Drives

External drives offer expanded storage and connect via USB, Firewire, or eSATA.

Floppy Disks

Floppy disks are largely obsolete due to their limited capacity and reliability issues.

CD-ROM and DVD

CD-ROMs and DVDs are optical storage devices. DVDs offer higher storage capacity and faster transfer rates than CDs.

Blu-ray

Blu-ray discs offer even higher storage capacity for high-definition video and data.

Flash Memory Cards

Flash memory cards are small, portable storage devices used in various devices, especially digital cameras.

Other Storage Devices

like CD-ROM or DV-DROM, to PCs. This standard is better known by the trade term IDE (Integrated Device Electronics) or E1DE (Enhanced IDE). With the advent of Serial ATA Serial ATA classic ATA / IDE has been renamed Parallel ATA or Parallel ATA, or what is the same, PATA. Transfer mode refers to how data is transferred from the hard drive into RAM. There are several techniques: • IOP: Input / departure. Use the system microprocessor as an intermediary for data exchange. It is the oldest method of transfer. Some IOP transfer modes are “PIO Mode 1: 5.2 Mb / s-PIO Mode 2: 8.3 Mb / s-PIO Mode 3: 11.1 Mb / s-PIO Mode 4: 16.6 Mb / s. .. DMA: It is a system designed to transfer data from RAM to the hard disk, and vice versa, without the microprocessor has to intervene in this task, freeing the CPU for other tasks. Currently UltraDMA system is used, known as UDMA. There are several versions that are known by the maximum transfer rate that allow:-DMA-16 or Ultra-DMA: 16.6 Mb / s-DMA-33 or Ultra-DMA-Mode-2, or Ultra-ATA / 33: 33.3 Mb / s-oo-UDMA or Ultra-DMA-Mode-4, or Ultra-ATA/Ó6: 66.6 Mb / s-UDMA-100 or Ultra-DMA-Mode-5, or Ultra -ATA/100: 100 Mb / s-UDMA-133 or Ultra-DMA-Mode-O, O Ultra-ATA/133: 133 Mb / s access time is the time used by the heads of read / write to register above sector to be read or write. This time should be between 9 and 12 milliseconds. Search time is the time it takes the drive to move the heads from one track to another. is between 8 and 12 milliseconds. Check the speed of rotation speed of the disc. Typical values are between 5400, usually on portable hard drives and 7200 rpm (revolutions per minute), on hard drives for desktop computers. In disks with SCSI interface, the speeds of rotation may be greater, 10000 or even 15000 rpm, although they are noisier and consume more energy. latency when moving the cylinder heads to the right, the unit must wait until the desired sector passes under head. This is known as latency, defined as the time required to rotate the disk and the sector to the correct position. The higher the rotational speed of the disc, the lower the latency. 6O is calculated by dividing (seconds per minute) between the speed of rotation. Storage Capacity While all features are important, the focus of a hard disk is full. At this time is measured in gigabytes (GB), although increasingly it is beginning to use The terabyte (TB). The manufacturers often round capacity with 1,000 megabytes to one gigabyte, which makes any discrepancies in calculating the total size, since it really a gigabyte is 1024 megabytes. cache disk cache disk readings stored so that when the controller requests data from the disk already has them available in its cache and not have to wait to change position heads.Other features to consider are: • The interface, which defines the connection mechanism between the drive and the PC. Desktop PCs and laptops often use ATA / IDE and SATA, SATA and SCSI servers, to external drives usually use USB, Firewire or eSATA. • Size: hard drives for desktop PCs typically have 3.5 “on laptops is usually 2.5 or 1.8 inches. • The noise, which often depends on the type of disc. The high speed of rotation, such as SCSI, are louder. • Maximum operating temperature. • Tolerance to shock and vibration. • The price. IBM launched its first hard drive to the market on 13 Septem ¬ ber 1956, he records the size of pizzas and could store 5 MB of data, its name was RAMAC (Random Access Memory Accounting), was the size of two refrigerators ¬ tion and weighed a ton. Hard drives ATA / IDE, better known as IDE (Integroted Device Electronics Integrated Drive Electronics) have been the most widely used until recently. Connecting the hard disk to the system shall be on a 40-pin ribbon cable that connects to the IDE interface or IDE connector on the motherboard. Current motherboards include one or two IDE connectors, or channels, but now more often than not find just one. When the motherboard has two IDE connectors one of them will be the primary IDE connector and the other the secondary IDE connector. Primary IDE connector connects the system boot drive. It is necessary to consult the motherboard manual to know the position of each. Each IDE interface supports up to two IDE devices, such as two hard drives, or hard drive and a DVD-ROM or CD. A. Master / slave Each interface or connector supports two IDE devices and each device must be identified. One was identified as a master (master) and one as a slave (slave) in the cable connector. There can be two teachers or two slaves on the same cable. IDE devices use jumpers (or bridges) to identify master / slave. They are usually located on the disk where the IDE connector is the jumper’s position is usually found on a sticker that sits on top of the disc. Typical configurations of the jumpers are: • Master in a cable with a single unit. Is usually on the disc label as Moster with non-ATA-slave. • Master in a two-unit cable. Moster or stand alone or Master or single orive. • Slave. Drive is or slave, or slave. • Cable Select to designate which unit is master and which slave. Cable Select or Cable Select Enable. Not all drives support all combinations, for it will be necessary to consult the documentation for each unit to determine with certainty the placement of the jumpers. To connect the hard drive uses a flat cable (or “strip”) of 80 drivers with 40-pin connectors. This cable has three connectors: one connects to the IDE connector on the motherboard and other connectors to the master and the slave device. Normally, the IDE connector that goes to the motherboard is codi ¬ fied by colors (blue, green …) to distinguish the connector that joins the master device, usually black, and the slave device, usually gray . To supply power to disk using a white connector from the power supply The first PC hard drive was invented in 1981. It had a capacity of 40 MB and a data transfer rate of 625 kbps. At the end of the year 1994 had drives of 260 Mb was the end of 1995 when it reached a gigabyte. Currently sold discs with a capacity of terabytes (1 TB = 1 000 GB = 1 million megabytes). The original name of the interface used by IDE interface is ATA [AT Attachment, ATA and IDE are basically the same).The ATA standard defines basic functions of the interface architecture, such as the number of pins on the cables used to connect the units to the system bus, configuration parameters master / slave or data transfer speeds. ATA-l (ATA, IDE) 8.3 Mb / s ATA-2 (Fast ATA, EIDE) 13.3 Mb / s ATA-3 (ATA-2 Enhanced) 16.6 Mb / s ATA-4 (ATA / ATAPI-4 or DMA or Ultra ATA/33) 33.3 Mb / s ATA-5 (ATA/ATAPI-5 or Ultra ATA / oo) 66.6 Mb / s ATA-OR (ATA / ATAPI-Ó or Ultra ATA / 100) 100 Mb / s ATA-7 (ATA/ATAPI-7 or Ultra ATA/133) 133.3 Mb / s Serial ATA has become the new standard for connecting hard drives. Introduced in February 2003 to compensate for the limitations of the standard ATA / IDE. The transfer rate is achieved with this interface is 150 Mb / s or 300 Mb / s. A first gear is better known as SATA/150 or SATA I, to the second, as SATA/300 or SATA II. SATA is being developed, 6 which includes a speed of 600 Mb / s. The committee set the Serial ATA standards is quite content to use the names SATA I, SATA II or SATA III SATA Revision 3 SATA 6 Gb / s SATA Revision 2 SATA 3Gb / s SATA Revision 1 SATA 1.5Gb / s SATA hard drives to use different IDE connectors; for it. The jumpers that bring in the back have nothing to do with the jumpers on IDE drives are used to configure a disk to a lower speed. For example, a SATA II 3Gb / s can be configured as a SATA I 1.5Gb / s. The data connector has a width of 10 mm and is composed of 7 wires and the electrical connector is flatter and has 15 connectors. The data cable can have 1 m long, as opposed to the IDE ribbon cables, which measure 45 cm. Each hard drive needs a data cable, which is not necessary to differentiate hard disk master slave. Since the BIOS can configure the boot order of devices. SATA is a serial connection (transmitting one bit after another) that creates a point to point connection between two devices. When handling a drive, we must take into account some precautions: • We should not hit the disk drives. • Should not be exposed to magnetic sources that may affect the information. • Do not open the disk. • Do not use very long screws to adjust the disc to the box. • They should preferably be used horizontally. When installed on a computer disk, the best way to detect their presence is accessing the BIOS and into the IDE HDD AUTO DETECTION option, which automatically detects the hard disks installed on your computer. The BIOS checks the devices that are connected to each IDE or SATA connector on the motherboard. Detect the disk size and disk geometry, ie the number of cylinders, heads and sectors in which the disk is divided. This information is displayed with the following parameters: SIZE, CYLS, and SECTOR HEAD respectively Disc Info in the BIOS. The most important thing is to make sure LBA mode is enabled, which most often is usually done automatically. When LBA mode is enabled, some BIOS changes the values of the cylinders and heads, this operation does not change the disk capacity. SCSI hard disks are not recorded in the system BIOS. In contrast, the adopter SCSI card includes its own BIOS, which will regulate all activities, regardless of the microprocessor. A computer with SCSI card adopter show information about the adapter in the boot process and can also access the adapter BIOS through a combination of keys such as Ctrl + A. Consider the meaning of some parameters which we found in the previous screen and can find other BIOS: • Primary Master and Primary Slave: these terms refer to devices connected as master and slave IDE connector 1 or the primary IDE channel.Remember that each ribbon cable can connect two IDE devices. • Secondary Master and Secondary Slave: refer to the IDE devices connected as master and slave IDE connector 2 or the secondary IDE channel. • SIZE: Size of disk in megabytes. • Precomp: cylinder number in which the disc changes the time of writing. In the new disks is not used. • Landzo: cylinder number where the heads of read / write positions when the disc is stopped. • MODE: Addressing mode disk. It may be normal (for older disks), Large or LBA. At present, BAL is the most common form of address and is used for disks larger than 528 Mb • CHS Capacity: refers to the capacity of the disk as cylinders, sectors and heads it has. • Maximum LBA Capacity: total capacity hard drive as LBA addressing mode. • Multi-Sector Transfers: refers to the number of sectors per block to be transferred when transferring multiple sectors. • SMART Moniíoring: Setting this parameter alerting the user about any errors that may occur in the hard disk. When we entered the detection area of discs in the BIOS, you can select AUTO in the disc type column TYPEj for every time the computer starts up automatically the values are placed. SCSI hard drives (Smalí Computer System Interface) are used in professional environments where there are high performance and reliability requirements. They are more expensive, are usually faster when transmitting data, with an almost constant transfer rate, and use less the microprocessor for this task. Computers are often used in workload, such as network servers. The SCSI interface supports more devices and more device types that the IDE interface and is generally not integrated into the motherboard. In most cases adopter card is required to be inserted into a slot on the motherboard SCSI adopter base.tarjeta which is inserted into a PCI slot, hard disk, SCSI and SCSI interface. The SCSI standards define the basic elements of the SCSI bus, including the number of devices that can connect to cable, cable length, signals, orders, transfer speed, etc.. Currently there are a variety of external hard drives that will allow us to expand the storage capacity of our PC, although there are models with more features, like playing video and sound, offering the possibility of connecting to the television to hear the stored music or see a movie. The most commonly used for storage facilities are those that connect via USB cable, depending on the size you require electrical connection or not. Not only used the USB port for connection to the PC, but there are also models that connect via FireWire and external Serial ATA (eSATA). The most used size for portable hard drives is 2.5 inches, although there are smaller, 1.8 inch, and larger than 3.5 inches. There are adapters on the market that allow us to connect internal hard drive to SATA or IDE via the USB port can also install on the PC case to have an external hard drive. This housing will be connected to IDE or SATA port on the motherboard, and when we want to work with the disk, only have to enter into the housing without Adapter IDE, SATA. install inside your computer case (see Figure 4.14). This system is commonly used when buying a new hard drive and want to keep the system opera ¬ rative of the old disk, so that we can boot the computer with a disk or another. You can also use when you want to copy an entire hard disk.In 1971, IBM entered the market the “memory disk”, or “floppy disk”, an 8-inch soft disc made of plastic and covered with iron oxide on one side, could store 100 kb of data. The stage for this disc could only read them. Over time, an improved technique to write well. The diskettes or floppy disks for many years were essential system data storage in computers, as well as the primary vehicle used for software distribution. When they appeared hard disks, floppy disks continued to keep for several reasons: it used to boot the system, for software deployment and provided a removable storage medium. Currently, the floppy drive tends to disappear, given their inadequate capacity for current needs and the lack of reliability. Its primary use is to boot the system and temporary storage of small files. Features A diskette is a very thin film of Mylar (polyester manufactured by DuPont), cut in circles and impregnated on each side with magnetic particles that are the real storage medium. The Mylar sheet is contained within a plastic box with a rectangular hole covered by a protective slider, usually metal, which shows the faces of the disc. The shield protects the disc from dust and dirt. In the lower left slot has a write protection. If you are covered can not be recorded on the disk data floppy disks are now the most widely used of Vh-inch double-sided and high density, or better known as V / i “HD. They have 80 tracks and 1 8 sectors per track on each side . The storage capacity will be: 80 tracks x 1 8 sectors x 2 sides x 51 2 bytes = 1 474560 bytes, or what is the same, 1.44 Mb in the top left of the floppy disk there is a slot that indicates whether the disk is high density (HD) and is used to distinguish them from older records that allowed only 720 kb of storage, these were known as double-sided discs and dual density: Vh “DD. They had 80 tracks and 9 sectors per track on each side. Floppy disks are unreliable devices for storing information because they are affected by heat, cold, humidity, magnetic fields, shock, dust, etc.., So if you have important data that we keep in a safe place we should not use floppies. The floppy diskette drive is an internal device that is mounted within a bay in the computer case, its size is similar to a hard drive. The front has to be visible so you can enter the disk write data on disks in the form of tracks, like hard disks, and on both sides. It comprises the following components: • The heads read / write. • The spindle motor, which makes the disk spinning inside the plastic box at a speed of 300 rpm. • The connector connecting the unit to the port on the motherboard (FDD). • The connector connecting the unit to the power supply. The data cable is a 34-pin ribbon cable with a strange twist in one end. In cables that allowed two floppy drives, this twisted ¬ aunt distinguish allow drive A B unit, the unit closest to the twisting is A. Currently, the only cable has two connectors: one to the motherboard and the other (next to twisted) to the floppy drive. A typical error when installing the floppy drive is connected incorrectly tar ¬ data cable. If the cable is installed backwards or improperly, the drive LED will light for the start of the computer and stays on all the time. Originally, floppy disks were used to provide software products and operating systems.Because of the increased size of these products, floppy disks gradually became less practical and replaced by the CD-ROM. The CD first appeared in 1982 in audio format. The CD-ROM ¬ rum appeared in 1984, they were very expensive, so he had to spend time to replace the floppy ¬ ran as a means of software distribution. These allow store up to 700 Mb The software has continued to escalate, and many software products currently ne-cesitar several CD-ROM. Then comes the DVD, which can store up to 17 Gb CD-ROMs and DVDs are optical storage devices. As in the disks, digital storage is, the drive reads a sequence of ones and zeros and converts them to computer format. Physically, they consist of a polycarbonate disc 12 cm in diameter and 1.2 mm thick with a central hole 1.5 cm in diameter. A. CD-ROM is the most common means currently used to store data. Manufacturing The manufacturing process of a compact disc or CD using a master disc which recorded the ones and zeros, which consists of a series of microscopic holes (or wells) using a high-power laser (rather than used to read the CD). This master disk is used to stamp the image in the polycarbonate of the CD. Once the CD has printed the data set, apply a deck of alu ¬ minium, which characterizes his usual brilliant and serves to reflect light laser read head. Then applied to the entire disc a thin protective layer of clear lacquer. Finally, the label is stamped above CD drives read into the underside of the disk (the one with no label), but the data set is stamped on the top side, underneath the label. The head of the unit sends a beam of light from the bottom of the disc, which is reflected in the aluminum layer. The amount of light reflected from the surface depends on the incident beam, if the beam strikes a pit, this is dissipated and the reflected intensity is much lower than when incident on a flat. The plains act as mirrors, reflecting almost all the light they receive. If we match the holes with the zeros and ones with the plains, we have a binary representation. The CD has a single spiral track starts in the central area of the disk and ends at the outer edge, the length is about 6 km. Formats There are many disc formats, the difference between them lies in the way it encodes information: • CD-DA (Compact Disk Digital Audio). It is intended for audio format. The rule that defines this format is in the Red Book. • CD-ROM (Compoct Disk Read Only Memory). It is commonly used to give Itís. The rule is found in the Yellow Book. • CD-R (Compact Disk Interactive). Defines the format for the interactive CD, which inte ¬ great text, graphics, video, audio and binary data (games, encyclopedias, films, etc.). The rule is in the Green Paper. • CD-ROM XA (CD-ROM Extended Architecture). It is a combination of CD-ROM and CD-I, designed to enhance audio and video capabilities, can also be used to store data only. • CD-R Multisession (CD Recordable). Define the format for recordable discs multi-session, with the possibility of adding data to a CD-ROM and print. The rule is in the Orange Book. • CD-RW Multisession (CD ReWritablej. Define the format for multisession rewritable discs, including the possibility to record, erase and re-record, as if it were a floppy disk. The rule is in the Orange Book. • Video CD (VCD) CD-Phofo. Defines the original video format (Video CD), which allows video recording with MPEG-1, with the possibility of storing 70 minutes of recording quality equivalent to that of a VHS video, both in audio and image, and Photo CD format.The rule is in the White Paper. • Super Video CD (SVCD). You can say it is a newer version of the CDV. It uses MPEG-2 instead of MPEG-1 and its resolution is quite acceptable, but the picture and audio quality is inferior to a DVD. Today almost all CD-ROM drives supported formats described above. Session and multisession. A session is a set of data that is entered once on a CD. Multisession is when we will write ¬ rials sessions on a CD. CD-ROM drives support CD-ROM only read accesses, it is not possible to delete, envelopes-write or amend the information recorded on the disc. It consists of the following: • The head read. It consists of a light source and a light receptor called photo-detector. The head sends light on the reflecting surface of the disk that contains the data and reads the reflected light detector. • The actuator head. Is responsible for moving the head on the disk surface to the track to be read. • The motor rotation. It is the spinning disk. The speed of the disc depend on the position of the head actuator. We have two options: maintain the constant linear velocity (CLV) or degiro remains constant velocity (CAV): – CLV (Constant Linear Velocity). Used by CD-ROM readers up to 1 2x, whereby the engine spins faster reader to read the inside of the disk when reading the outside, resulting in a constant rate of reading the entire disk. -CAV (Constant Angular Velocity). Is the technology used in readers lox and above, by which the reader reads data faster on the outside of the disk on the inside. • disc loading mechanism. Is responsible for inserting the CD into the drive. Often used a plastic tray that is managed by the touch of a button from the front of the unit. The disks are placed in the tray with the label side up. The front of the unit reveals a number of elements. Among them are the headphone output, volume control, the LED which indicates when it is running the CD, the eject button and stopping the CD from the drive, and the Play button and advance M. All these keys are usually independent of the software, although this usually takes precedence over the press. ATAPI [Advance Technology Atta-nterfocej chment Packet-go is the interface is used It will connect devices like hard disks, CDs, magnetic tapes or other removable media Letica. 3ermite using standard cable used by IDE disks and Dú ¬ you naestro or be configured as slave, like a hard IISc. ATAPI evolved; s a way of ATA interface. Most usually have a hole in the front, whose mission is to eject the discs that are blocked by inserting a thin screwdriver in the ori ¬ surface. Just a small pressure to the drive to unlock and leave open the disc. Transfer Rate The speed of a CD-ROM expresses the rate of data transfer and is expressed by a number followed by an ‘x’, for example, “52x”. The first CD-ROM operating at the same speed as the standard audio CD: 150 kb / s. The sign “x” is used to express the CD-ROM data transfer rate reaches 2, 4, 1 or 24, 48, 52 times the previous speed. Therefore, the transfer rate for 52x CD-ROM is 52 x 150 = 7800 kb / s. However, most manufacturers often add the word “MAX” to this figure. Meaning that the maximum transfer rate that can reach the reader, in case of 52x, 7800 kb / s. This is because today’s readers use the speed CAV, where the rate of data transfer on the outside of the disk is larger than in the interior.Interface The CD-ROM drive is connected to the IDE iface system just like they did with the hard drives. The rear of the unit consists of the power connector, the connector IDE / ATAPI, the umpers or bridges to configure the drive as master or slave, the digital output connector and audio connector for analog audio output connected to a sound card. Power connector Analog audio connector connector IDE / ATAPI SCSI interface can also be used in CD, although they are much more expensive. Currently it is beginning to generalize the SATA interface. External drives usually use the USB port and FireWire. DVD initially was called to the DVD digital video disc, it was intended to save movies, but when they discovered its potential for saving data was changed by the nom ¬ ber digital versatile disk. The main features of DVD is its speed and storage capacity. The DVD features are the same size as the CD but can contain more data, for several reasons: • The length of the microscopic holes used to encode data on the DVD are lower than in the CD. • The tracks on a DVD are closer than a CD. • A DVD can have two data layers: an opaque and a translucent layer. The unit can read ¬ ing the two layers the laser focus to one or the other. • A two-disc DVD is stuck against each other this makes it possible that data may have on both sides of the disc. However, DVD drives have a single head to read a face, so if you want to read the other side is necessary to flip the disc. Each face of the disc can turn two layers of data. • The DVD uses a more effective method of detecting and correcting errors. As for transfer speed, we must bear in mind that a DVD “1x” transfers data at 1385 kb / s, equivalent to a CD-ROM 8x. Currently there are DVD players units with a speed of 16x, but most CD-ROM read speeds greater than 48x. The storage capacity of a layer of a DVD is 4.7 GB if you use two layers for recording data, the second has a capacity of 3.8 Gb most used capabilities for DVD, according to the number of faces used and the number of data layers LightScribe technology will allow us to draw the label on a disc by the laser recorder. The recorder must be compatible with this technology normally seen LightScribe logo on the front. CDs and DVDs must be able to allow that is, not just any disk. 5 = 1cara 1cap DVD = 4.7 GB DVD 9 = 1caras 2capas = 8.5 GB DVD 10 = 2caras 1cap = 9.4 GB DVD 18 = 2caras 2capas = 17 Gb DVD dual format disc recording DVD.Permiten positive negative. Combo units. These units welded together two units one device, usually a DVD-ROM drive and a CD-RW (not recorded on DVD, but read them). Formats There are several types of DVD formats: • DVD-ROM: Used for digital data storage read-only. DVD-ROM drives are those that are typically installed on computers. • DVD-Video: Used for digital video storage for movies in MPEG-2. • DVD-Audio: Used for storing digital audio, similar to the propor-nated by CD-DA. • DVD-R (recordable) disc is a WORM-type (stands for “write once, read many), which can record up to 4.7 GB, but only once. • DVD-R DL: dual layer recordable DVD, each with a capacity of 4.7 Gb, giving a total capacity of 8.5 GB can only be graded by DVD-R DL. The older players have problems when reading such discs.• DVD-RW (read / write): A rewritable DVD that can be rewritten up to a thousand times. The recording system is similar to CD-RW discs. You can read a DVD-ROM. • DVD + R: This format is different than the previous two, since its recording system is different. You can only record once. • DVD + RW: A DVD + R to rewrite. • DVD + R DL: It is a derivative of DVD + R. This is a dual-layer recordable DVD, each with a capacity of 4.7 GB, with a total capacity of 8.5 GB Discs can be read in many of the latest DVD devices and can only be created using DVD + R DL and Super-Multi devices. • DVD-RAM: This DVD comes in cartridges that are necessary to make the recording, it is a rewritable DVD and is targeted at areas most professional. The access time to data is much lower than in the other formats, and allows real-time digital video with high-end digital cameras. This format is called DVD-VR. Need a DVD-RAM to be read. Physically DVD drives, drives readers and DVD burners are very similar to the drives and CD readers. It is sometimes difficult to distinguish with the naked eye, especially if they lack labels. On the front we can find the disc tray, the eject button, the emergency eject hole and the indicator or indicators of activity of the unit (see Figure 4.20). On the back of the unit will often find elements similar to those seen for the CD: the power connector or power, the data connector (IDE / ATAPI, SATA), the umpers and output connectors analog audio and digital audio. Currently, it is increasingly common to find units that use the SATA interface, making the jumpers to configure the master-slave device are unnecessary. Figure 4.20 shows the back of a DVD recorder unit with three connectors: the power connector, SATA connector and a third connector that is used to connect a games console. SATA connector front and back of a DVD recording drive. The following is a series of tips to protect disks: • Do not bend, heat and scratch the disc. • Do not use chemicals to clean the disc, instead use a soft cloth and dry. It will hold the disc by the edges and cleaned radially from the center outwards. Do not clean in circular motions. • Do not put labels on a hard disc, unless designed for that purpose. • Do not use pens that contain alcohol ink to write on the discs, the ink can penetrate the lacquer disk and data corruption. Units recorders CD drives and DVD burners look similar to the reading units. At first, when they appeared high prices and now a DVD recorder drive can be found for less than 30 €. Today, almost all computers that are purchased include a recording unit. Almost all DVD writers can read and burn CDs. When com-PRAM drive DVD recorder indicates the formats that can record and burn speeds for both DVD and CD. For example, a DVD recording drive to record in the following formats: CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-R, DVD-RAM, DVD-RW, DVD + RW, DVD + R , DVD + R DL, DVD-R DL. The speeds for reading, writing and rewriting are these: • Read Speed 48x (CD) / 1 óx (DVD). • Write Speed 48x (CD) / 1 8x (DVD ± R) / 8x (DVD-R DL) / 10x (DVD + R DL). • Rewrite Speed 32x (CD) / Ox (DVD-RW) / 8x (DVD + RW) /! 2x (DVD-RAM). We also indicate whether technology supports LightScribe disc labeling. D. BLU-RAY Blu-ray Disc or BD is an optical disc format designed to store high definition video and data.Their storage capacity is 25 GB for the basic model of single layer and 50 GB for dual layer model. Work is currently in multilayer technology, so as to reach higher capacities of 400 GB are common features: • Uses technology blue-violet laser (405 nm), much thinner than the red lasers used on CD or DVD (750 or 650 nanometers, respectively), hence its name [Blue Ray Blue Ray is in Spanish) (a nanometer is 1 x 10 ~ 9 meters). This raises in support of the same size fit more information. Support high resolution video (HD), maximum 1 920 x 1 080 pixels, at a speed of 24 frames per second progressive mode. Supports image compression formats MPEG-2, MPEG-4 and VC-1. The data transfer rate than any other format, 54 Mbps Types There are currently three types of Blu-Ray: • BD-ROM. Just reading it is used for movies, games, software, and so on. • BD-R. Recordable once. • BD-RE. Rewritable, Recordable more than once. We should add that all players, and even recorders are compatible with CD and DVD formats. For example, BD-ROM player can read DVD + RW / + R DL / + R, DVD-RW/-R DL /-R, DVD-RAM, DVD-ROM, DVD-Video, DVD-Au ¬ gave , CD-RW/-R, CD-ROM, CD-ROM XA, and so on. MPEG (Moving Picture Experts Group). Panel moving image, a group of people responsible for generating standards for digital video and audio compression. Has standardized MPEG compression formats if ¬ lowing and ancillary standards: MPEG-1, MPEG-2, MPEG-3, MPEG-4, MPEG-7 and MPEG-21. Applications Some applications of Blu-ray technology include: • High Definition Television (HDTV-High Definition Television). HDTV is characterized by ¬ za television emit signals with superior digital quality. This increases the need for space to record a TV signal high defi ¬ nition without quality loss. Blu-Ray discs provide sufficient capacity for HDTV resolution record favorite television programs. • Data storage and backup. • Development of video games. Sony’s Playstation 3 is the first video game console that has Blu-Ray. • Studies of film / TV. The film and television productions in the future will work with HD (High Definition), HDTV, and they will need reliable storage media with greater capacity and faster access times. • Home Computing. Gradually, are introduced Blu-Ray players in personal computers, users can enjoy its benefits both at work and at home. Flash memory cards are some small portable devices with large storage capacity, rather resistant to shocks and low power consumption. They use many devices, like mobile phones, PDAs, audio players, but undoubtedly the most popular are digital cameras. Flash memory is a type of memory EEPROM (Electrically-Erasable Read-Only Memory Programmoble, electrically erasable programmable ROM), and is a nonvolatile memory, ie, preserves data when switched off the device that feeds it. The data transfer speed depends on chip memory controller and interface. Formats There are many formats, and increasingly have greater storage capacity. They have a similar shape: a rectangle of plastic and almost always black. However, there are many models. The most popular are: • CompactFlash (CF). It was the first type of flash memory that became popular in the beginning (see Figure 4.22). Currently there are two types: CF I, 43 x 36 mm and 3.3 mm thick, and CF II, 43 x 36 mm and 5.5 mm thick, the latter less used for flash memory.The speed varies depending on the standard CF. The 2.0 is defined pecificación ¬ 1 or Mb / s, 3.0, óó Mb / s specification 4.0, 133 Mb / s. The storage capacity can reach up to 1 GB • 37 SmartMedia Card (SMC). Very similar to above but something finer, lower cost and in a different manufacturer. Its maximum capacity is 1 28 Mb and is now extinct. • Memory Stick (MS) and Memory Stick PRO. Format used by Sony in their digital cameras, PDAs and digital music players (see Figure 4.23). It is charac ¬ tica form of thin rectangular stick, its original capacity was 128 Mb subsequently developed the Memory Stick PRO and small versions such as Memory Stick PRO Duo, with a current capacity of 1 or Gb, and Memory Micro/M2 Stick with a current capacity of 8 GB has recently been developed Memory Stick PRO HG, allowing speeds of 30 Mb / s. • Secure Digital or SD. Memory is a type of very small size and weight (24.0 x 32.0 mm x 2.1 mm thick and 2 g), but their ability cenamiento ¬ soul is very high (see Figure 4.24) . Usually have a Security tab that prevents overwriting stored information, similar to floppy disks. Some varieties of SD cards are SDIO (SD input / output), small devices such as modems, WiFi or Bluetooth wireless connectors, cameras, GPS, etc.., We can connect using the SD slot. • Secure Digital High Capacity (SDHC). The SD 2.0 standard review led to SDHC cards physically the same as SD, but with capacity between 2 and 32 Gb We distinguish several classes to differentiate the transfer rate:-Class 2: minimum guaranteed speed of 2 Mb / s. -Class 4: minimum guaranteed rate of 4 Mb / s. -Class or: guaranteed minimum speed or Mb / s. Just keep in mind that devices compatible with SD cards SDHC cards accepted, but not vice versa. • Multimedia Card / MMC. They are similar to SD but less thick (see pure MMC cards up to the 25th came Mb cards currently exist, such as the MMCplus and MMCmobile (mini size) based on the MMC 4.0 specification, which offer speeds up to 52 Mb / s, and although they have different connections are compatible with conventional MMC. Currently, the maximum storage capacity is 4 GB xD-Picture Card (xD). It is a type of memory developed by Fujifilm and Olympus that used in their digital cameras. There are three types: standard xD, xD Type A / 1 and xD Type H, which differ in capacity and write speed, more speed to be that of the latter type. As a proprietary model, is less common causes than other cards. 9 Cards mini. Almost all types of cards have seen before smaller formats for small devices such as mobile phones or PDA. The most common are:-Reduced Size MultiMediaCard (RS-MMC). — MMCmobile. “SD.” microSD. “Memory Stick Duo.” Memory Stick Micro/M2. The tape or streamers are data storage devices. The data are recorded sequentially, so that to access certain information is necessary to read above. To add and delete data in a tape should be a new record with new information. Its most common use is to make backup copies (back-ups) of information to prevent accidental loss if something happened to hard drives. Among the disadvantages are the need for special software to make copies and tremendous slow to read and write data. ZIP disks are magnetic devices a little larger than floppies, although more robust and reliable. His ability ¬ ity storage is 100 and 250 Mb, depending on version. The data transfer speed does not exceed the hard disks, but that of the classical drive.Currently not used. SuperDisk disks are storage positive dis ¬ fully compatible with 3.5-inch diskettes. The first version (LS-120) allow ¬ aunt a capacity of 120 Mb and the second version (LS-240), 240 Mb is currently out of print. B. Card Readers While these cards are widespread, many desktops do not have the necessary slots to read them, whereas nearly all notebooks sold today have a slot that can read several types of cards. To overcome these problems, many readers are commercially available and fairly cheap card adapters that connect to standard computer ¬ mind through the USB port. There are also adapters for mini cards read, that connect via USB or even older card slots (see Figure 4.27). There are also upfront with different slots for different card models that can be attached to the computer case C. USB Flash Drives Pendrives. Also known as ‘key’, ‘pencil’, ‘prod’, ‘USB stick’ … It is a small device that plugs into the USB port for easy data transfer. By connecting, the computer will detect a new storage device. No drivers are needed for Windows XP, 2000, Me, Vista, etc.., But for Windows 98. Currently on the market in a capacity that exceeds the 16 GB is the most commonly used removable media.