The System Unit

Flash Memory 
A special type of EEPROM that can be erased and reprogrammed in blocks instead of one byte at a time. Many modern PCs have their BIOS stored on a flash memory chip so that it can easily be updated if necessary.  Flash memory is also popular in modems because it enables the modem manufacturer to support new protocols as they become standardized. Flash memory is also called flash RAM.

Graphic Cards

A graphic card (also video card) is a piece of hardware installed in a computer that is responsible for rendering the image on the computer’s monitor or display screen. The first consideration when buying a graphics card is to be sure it is capable of displaying the best resolution the monitor can support. The second consideration is on-board memory. A graphics card must work very hard to render images to the screen. Unlike text files, graphics images are much larger files consisting of great amounts of data that must be processed by the graphics or video card.

Sound Cards

An expansion board that enables a computer to manipulate and output sounds. Sound cards are necessary for nearly all CD-ROMs and have become commonplace on modern personal computers. Sound cards enable the computer to output sound through speakers connected to the board, to record sound input from a microphone connected to the computer, and manipulate sound stored on a disk.

Network Interface Card (NIC)

Often abbreviated as NIC, an expansion board you insert into a computer so the computer can be connected to a network. Most NICs are designed for a particular type of network, protocol, and media, although some can serve multiple networks.

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. Since the introduction of the NuBus, the Apple Macintosh has been a plug-and-play computer.

Bus Line

In computer architecture, a bus is a subsystem that transfers data between computer components inside a computer or between computers. Early computer buses were literally parallel electrical buses with multiple connections, but the term is now used for any physical arrangement that provides the same logical functionality as a parallel electrical bus.

HDMI

HDMI (High-Definition Multimedia Interface) is a compact audio/video interface for transmitting uncompressed digital data. It is a digital alternative to consumer analog standards, such as radio frequency (RF) coaxial cable, composite video, S-Video, SCART, component video, D-Terminal, or VGA. HDMI connects digital audio/video sources (such as set-top boxes, upconvert DVD players, HD DVD players, Blu-ray Disc players, AVCHD camcorders, personal computers (PCs), video game consoles such as the PlayStation 3, Xbox 360, and AV receivers) to compatible digital audio devices, computer monitors, video projectors, and digital televisions.

 

Cache Memory
A memory cache, sometimes called a cache store or RAM cache, is a portion of memory made of high-speed static RAM (SRAM) instead of the slower and cheaper dynamic RAM (DRAM) used for main memory. Memory caching is effective because most programs access the same data or instructions over and over. By keeping as much of this information as possible in SRAM, the computer avoids accessing the slower DRAM.

Secondary Storage

File Compression


Compression is useful because it helps reduce the consumption of expensive resources, such as hard disk space or transmission bandwidth. On the downside, compressed data must be decompressed to be used, and this extra processing may be detrimental to some applications.

In computer science and information theory, data compression or source coding is the process of encoding information using fewer bits (or other information-bearing units) than an unencoded representation would use, through use of specific encoding schemes.



Head Crash

 A head crash usually means that the head has scratched or burned the disk. In a hard disk drive, the head normally hovers a few microinches from the disk. If the head becomes misaligned or if dust particles come between it and the disk, it can touch the disk. When this happens, you usually lose much of the data on the hard disk and will need to replace both the head and the disk. Head crashes are less common for floppy disks because the head touches the disk anyway under normal operation.

Another term for head crash is disk crash.

                                     Optical Disk Drive

 A storage medium from which data is read and to which it is written by lasers. Optical disks can store much more data up to 6 gigabytes (6 billion bytes) -- than most portable magnetic media, such as floppies. There are three basic types of optical disks:  CD-ROM, WORM, erasable.

These three technologies are not compatible with one another; each requires a different type of disk drive and disk. Even within one category, there are many competing formats, although CD-ROMs are relatively standardized.

Solid-State Storage

is a nonvolatile, removable storage medium that employs integrated circuits rather than magnetic or optical media. It is the equivalent of large-capacity, nonvolatile memory. Examples include flash memory Universal Serial Bus (USB) devices and various proprietary removable packages intended to replace external hard drives.

                                     
                                      Internet Hard Drive

Since the advent of digital media, there has been a need to store and retrieve media. Internet hard drives have served to meet this need, offering a creative new solution to the issue of data storage.

The sole purpose of an Internet hard drive is to offer a means of accessing your computer files (pictures, documents, music, videos, etc.) from any computer, as long as that computer has access to the Internet.

Unlike your local hard drive, which may have a limited storage capacity, a competitive Internet hard drive provider will offer virtually unlimited disk space.

Input And Output

Ergonomic Keyboard

An ergonomic keyboard is a computer keyboard designed with ergonomic considerations to minimize muscle strain and a host of related problems.

 

                                                                    
                                                                     Ink-Jet Printer

 

 type of printer that works by spraying ionized ink at a sheet of paper. Magnetized plates in the ink's path direct the ink onto the paper in the desired shapes. Ink-jet printers are capable of producing high quality print approaching that produced by laser printers. A typical ink-jet printer provides a resolution of 300 dots per inch, although some newer models offer higher resolutions.

Laser Printer


Electrostatic printer that focuses a laser beam to form images that are transferred to paper electrostatically.

Laser printer is a type of printer that utilizes a laser beam to produce an image on a drum. The light of the laser alters the electrical charge on the drum wherever it hits. The drum is then rolled through a reservoir of toner, which is picked up by the charged portions of the drum. Finally, the toner is transferred to the paper through a combination of heat and pressure. This is also the way copy machines work.

Magnetic-ink character recognition (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. Unlike barcodes or similar technologies, however, MICR codes can be easily read by humans.

Optical-Character Recognition (OCR)

Optical Character Recognition (OCR) is a process of converting printed materials into text or word processing files that can be easily edited and stored. The technology has enabled such materials to be stored using much less storage space than the hard copy materials. OCR technology has made a huge impact on the way information is stored, shared and edited. Prior to optical character recognition, if someone wanted to turn a book into a word processing file, each page would have to be typed word for word.

Optical-Mark Recognition


Short for optical mark recognition, the technology of electronically extracting intended data from marked fields, such as checkboxes and fill-infields, on printed forms. OMR technology scans a printed form and reads predefined positions and records where marks are made on the form. This technology is useful for applications in which large numbers of hand-filled forms need to be processed quickly and with great accuracy, such as surveys, reply cards, questionnaires and ballots. A common OMR application is the use of "bubble sheets" for multiple-choice tests used by schools.