SD

=STORAGE DEVICES = Instructions to upload your contribution: 1. Click on EDIT (top right tab) 2. Write your name in brackets (for example [Maria Jose Mora]) 3. Write a title with the name of your component 4. Copy the information you wrote in your word document 5. Upload no more than three pictures from the ones saved in the hub. 6. Write all the websites you used for your research. 7. __Don't forget to Save your Work!__

[James kulubya} __DVD[[image:http://t3.gstatic.com/images?q=tbn:ANd9GcRimBHyNb6vZdtfhrwSSqhFx3nEFJexvA5wTJXXBfLbKr0scvU&t=1&h=165&w=225&usg=__G74easQ2z-Dnawo_kHufct-Y3dE3 width="60" height="64"]]__ =// __ Introduction __ //= // DVD ////, also known as Digital Video Disc or Digital Versatile Disc, is an optical disc storage media format, and was invented and developed by Philips, Sony, Toshiba, and Time Warner in 1995. // // Its main uses are video and data storage. DVDs are of the same dimensions as compact discs (CDs), but are capable of storing just less than seven times as much data. // =

= //__ History __// =

= // In 1993 two optical disc storage formats were being developed. One was the Multimedia Compact Disc (MMCD) also called Cdi+, backed by Philips and Sony, and the other was the Super Density (SD) disc, supported by Toshiba, Time Warner, Matsushita Electric, Hitachi, Mitsubishi Electric, Pioneer, Thomson, and JVC. // =

=   =

= //__ CD __// =

= //__ Introduction __// =

= // Compact Disc //// (also known as a CD) is an optical disc used to store digital data. It was originally developed to store sound recordings exclusively, but later it also allowed the preservation of other types of data. Audio CDs have been commercially available since October 1982. In 2010, they remain the standard physical storage medium for audio. // =

=// Standard CDs have a diameter of 120 mm and can hold up to 80 minutes of uncompressed audio (700 MB of data). The Mini CD has various diameters ranging from 60 to 80 mm; they are sometimes used for CD singles or device drivers, storing up to 24 minutes of audio. //// The technology was eventually adapted and expanded to encompass data storage CD-ROM, write-once audio and data storage CD-R, rewritable media CD RW, Video Compact Discs (VCD), Super Video Compact Discs (SVCD), PhotoCD, PictureCD, CD-i, and Enhanced CD. //=

= //__ Bibliography __// =

= //__ Wikipead: Compact disk __// =

= //__ Wikipead: DVD __// =

=[Nandi Masembe]=

= **__ Flash Drives __**  =

= **//__ What is a Flash Drive? __//** =

= A flash drive, also called a jump drive, pen drive, thumb drive, flash stick or memory stick is a small flash memory drive with a USB (Universal Serial Bus) connection. Most computers have at least two USB ports which are usually located in the back of the computer tower or on the sides of a laptop computer. Flash drives can hold from 64 MB to upwards of 2 GIG of data. A 64 MB flash drive can store the same amount data that is equal to the same amount of data stored on about 44 floppy disks. This makes it much more convenient to carry around flash drives rather than floppy disks or zip disks. Flash drives are read and write a disk which means you can open (read) and save files to the disk. =

=   =

= **//__ How does a Flash Drive work? __//** =

= You put it into a USB port in the computer, and the computer will recognize it as a drive, for example, the H drive, and you can drag files on or off of them, and they are rewritable so items can be taken on and off without having to buy a new flash drive, unlike the CD. They must be ejected safely through the computer, or files may be lost on them forever. Flash drives use flash memory. Electronic memory comes in a variety of forms to serve a variety of purposes. Flash memory is used for easy and fast information storage in computers, digital cameras and home video. It is used more like a hard drive than as RAM. In fact, flash memory is known as a ** solid state storage device, which means there are no moving parts and it’s an input and output device. ** =

= ** @http://www.lakeland.cc.il.us/online/tutorials/flashdrive/print/flashdrive.pdf ** =

= ** @http://wiki.answers.com/Q/How_does_a_flash_drives_work @http://www.suite101.com/content/how-does-a-flash-drive-work-a79898 ** =

= ** @http://electronics.howstuffworks.com/flash-memory.htm ** =

= **__ How Hard Drives Work __**  =

=[Helen Barton]=

= Almost every desktop computer and server in use today contains one or more hard-disk drives. Every mainframe and supercomputer is normally connected to hundreds of them. You can even find VCR-type devices and camcorders that use hard disks instead of tape. These billions of hard drives store changing digital information in a relatively permanent form and they give computers the ability to remember things when the power goes out. =

= =

= These are the parts of a hard drive: =

= = When the power to a PC is switched off, the contents of memory are lost. It is the PC's hard disk that serves as a non-volatile, bulk storage medium and as the repository for a user's documents, files and applications. It's astonishing to recall that back in 1954, when IBM first invented the hard disk, capacity was a mere 5MB stored across fifty 24in platters. 25 years later Seagate Technology introduced the first hard disk drive for personal computers, boasting a capacity of up to 40MB and data transfer rate of 625 KBps using the MFM encoding method. A later version of the company's ST506 interface increased both capacity and speed and switched to the RLL encoding method. It's equally hard to believe that as recently as the late 1980s 100MB of hard disk space was considered generous. Today, this would be totally inadequate, hardly enough to install the operating system alone, let alone a huge application such as Microsoft Office. ==
 * 1)  Actuator (compact electric motor that moves the read-write arm).
 * 2)  Read-write arm swings read-write head back and forth across platter.
 * 3)  Central spindle allows platter to rotate at high speed.
 * 4)  Magnetic platter stores information in binary form.
 * 5)  Plug connections link hard drive to circuit board in personal computer.
 * 6)  Read-write head is a tiny magnet on the end of the read-write arm.
 * 7)  Circuit board on underside controls the flow of data to and from the platter.
 * 8)  Flexible connector carries data from circuit board to read-write head and platter.
 * 9)  Small spindle allows read-write arm to swing across platter.

= The PC's upgradeability has led software companies to believe that it doesn't matter how large their applications are. As a result, the average size of the hard disk rose from 100MB to 1.2GB in just a few years and by the start of the new millennium a typical desktop hard drive stored 18GB across three 3.5in platters. Thankfully, as capacity has gone up prices have come down, improved areal density levels being the dominant reason for the reduction in price per megabyte. =

= It's not just the size of hard disks that has increased. The performance of fixed disk media has also evolved considerably. When the Intel Triton chipset arrived, EIDE PIO mode 4 was born and hard disk performance soared to new heights, allowing users to experience high-performance and high-capacity data storage without having to pay a premium for a SCSI-based system. =

= The hard drive is an input device because you put stuff in to the computer and then it can help you find stuff if it shuts down or you exit some thing without saving. This is one =

= []  =