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    • Secondary Storage

    Tuesday, January 18, 2011

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    File Compression

    The process of transforming information from smaller representation from which the original, can be retrieved. Encoding and decoding are often used to describe the compression and decompression processes. It has important applications in the areas of data storage and data transmission. Other than compression savings, other concerns include encoding and decoding speeds and workspace requirements, the ability to access and decode partial files, and error generation and propagation.



    Head Crash

    A head crash is a hard-disk failure that occurs when a read–write head of a hard disk drive comes in contact with its rotating platter, resulting in permanent and usually fatal damage to the magnetic media on the platter surface.

     

    Internet Hard Drive

    Its main purpose is to offer a gateway of accessing your computer files (pictures, documents, music, videos, etc.) from any computer, as long as that computer has access to the Internet. An Internet hard drive will allow you to "deposit" your computer files into a remote hard drive, and then later access those very same files from any other computer.

    

    
    Optical Disc Drive

    It is a disk drive that uses laser light or electromagnetic waves near the light spectrum as part of the process of reading or writing data to or from optical discs. Some drives can only read from discs. However, recent drives are commonly both readers and recorders. Recorders are sometimes called burners or writers. Common types of optical media include compact discs, DVDs, and Blu-ray discs which can be read and recorded by such drives.

     


    Solid-State Storage

    It is a data storage device that uses solid-state memory to store persistent data. SSDs are distinguished from traditional hard disk drives (HDDs), which are electromechanical devices containing spinning disks and movable read/write heads. On the other hand, SSDs use microchips which retain data in non-volatile memory chips and contain no moving parts. SSDs are typically less sensitive to physical shock, quieter, and have lower access time and latency. They use the same interface as hard disk drives, thus easily replacing them in most applications.

     

    Input and Output

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    Ergonomic Keyboard

    A keyboard that separates the keys into two halves shaped like a wide "V" is known as an ergonomic keyboard. While others are movable, some keyboards have a fixed layout. It puts less stress on the hands and wrist and winds up being comfortable for most people.


     


    Ink-jet Printer

    They are high-speed computer-driven printer that sprays a row of fine streams of ink onto labels and/or forms to create a dot pattern print image. Continuous lines can be formed by the appearance of small and dense dots. Ink-jet printers have several advantages over impact printers, such as speed, dual addressing, and personalization. Unfortunately, they are not able to supply the greater personalization, image orientation, and type-font flexibility of laser printers.






    Laser Printer

    A printer that uses a laser and the electrophotographic method to print a full page at a time. The laser "paints" a charged drum with light, to which toner is applied and then transferred onto paper. Desktop laser printers which is similar to copy machines, use cut sheets. Meanwhile, large printers may use paper rolls that are cut after printing.



    Magnetic-ink character reader (MICR)

    Magnetic Ink Character Recognition, or MICR, is a character recognition technology used primarily by the banking industry to facilitate the processing of cheques. The technology allows computers to read information (such as account numbers) off of printed documents. However, MICR codes can be easily read by humans unlike barcodes.



    Optical-character recognition (OCR)

    It is basically a scanning and comparison technique intended to identify printed text or numerical data. OCR software attempts to identify characters by comparing shapes to those stored in the software library. The software tries to identify words using character proximity and will try to reconstruct the original page layout. High accuracy can be obtained by using sharp, clear scans of high-quality originals. The down side is, the accuracy decreases as the quality of the original declines.


     



    Optical-mark recognition (OMR)

    Many traditional OMR (Optical Mark Recognition) devices work with a dedicated scanner device that shines a beam of light onto the form paper. To detect the marked areas, the contrasting reflectivity at predetermined positions on a page is then utilized because they reflect less light than the blank areas of the paper.



    The System Unit

    Thursday, January 6, 2011

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    Flash memory
    A non-volatile computer storage chip that can be electrically erased and reprogrammed is called a flash memory. It is primarily used in memory cards, USB flash drives, MP3 players and solid-state drives for general storage and transfer of data between computers and other digital products. It is a specific type of EEPROM (electrically erasable programmable read-only memory) that is erased and programmed in large blocks; in early flash the entire chip had to be erased at once.

    

    
    Graphic cards
    It plays an essential role in the PC. It takes the digital information that the computer produces and turns it into something human beings can see. The graphics card on most computers converts digital information to analog information for display on the monitor. On laptops, the data remains digital because laptop displays are digital.
     

    Sound cards
    It is an internal computer component that processes audio files in order to provide high-quality playback through computer speakers. It plays voice as well as music files, and can handle various audio file formats including .wav, .mp3 and .cda to name but a few. An interface is available on a typical sound card located at the back of the computer with various input and output ports. The overall sound quality of the computer system is affected by both the quality of the sound card and speakers. Speakers plug directly into the back of the sound card.

    

    Network interface card (NIC)
    More commonly referred to as a NIC, it is a device that allows computers to be joined together in a LAN, or local area network. Networked computers communicate with each other using a given protocol or agreed-upon language for transmitting data packets between the different machines, known as nodes.  To both send and receive data on the LAN, the network interface card acts as the liaison for the machine.

    

    Plug and play
    Refers to the ability of a computer system to automatically configure expansion boards and other devices. You should be able to plug in a device and play with it, without worrying about setting DIP switches, jumpers, and other configuration elements. The Apple Macintosh has been a plug-and-play computer, since the introduction of the NuBus.


    

    Bus line
    A collection of wires through which data is transmitted from one part of a computer to another. You can think of a bus as a highway on which data travels within a computer. The term bus usually refers to internal bus, when used in reference to personal computers. This is a bus that connects all the internal computer components to the CPU and main memory. There's also an expansion bus that enables expansion boards to access the CPU and memory.


     
    

    HDMI
    HDMI (High-Definition Multimedia Interface) is an interface standard used for audiovisual equipment such as high-definition television and home theater systems. HDMI is able to carry a bandwidth of 5 Gbps (gigabits per second) with 19 wires wrapped in a single cable that resembles a USB wire. This is more than twice the bandwidth needed to transmit multi-channel audio and video, future-proofing HDMI for some time to come. This and several other factors make HDMI® much more desirable than its predecessors, component video, S-Video and composite video.



     

    Cache memory
    It is an extremely fast memory that is built into a computer’s central processing unit (CPU), or located next to it on a separate chip. Cache memory is used in the PC to store instructions that are repeatedly required to run programs, improving overall system speed. The advantage is that the CPU does not have to use the motherboard’s system bus for data transfer. The data transfer speed slows to the motherboard’s capability, whenever data must be passed through the system bus. By avoiding the bottleneck created by the system bus,  the CPU can process data much faster .