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Sunday 29 May 2011

System Unit

Random Access Memory.




RAM, short for Random access memory is a type of computer storage that stores data which is easily accessed in any order with a worst case performance of constant time. This is a volatile, which means when there is a power failure, or the power has been removed from the system, the information is lost unless if it’s saved. The two main forms of modern RAM are static (SRAM) and dynamic RAM (DRAM). In static RAM, a bit of data is stored using the state of a flip-flop. This form of RAM is more expensive to produce, but is generally faster and requires less power than DRAM. DRAM stores a bit of data using a transistor and capacitor pair, which together comprise a memory cell.


Cache.



Cache is a component that transparently stores data so that future requests for that data can be served faster. The information that’s been inserted within a cache might be important that have been computed earlier or duplicates of original values that are stored elsewhere. If the data requested is stored in a cache, it is easier to read the cache, which is relatively faster. If not, the data must be taken from the original storage location which usually takes time. Therefore, the more the requests can be served from the cache, the faster the overall performance is. There are different sorts of cache, such as, CPU cache, Disk cache and Web cache, Hardware implements cache as a block of memory for temporary storage of data likely to be used again. CPUs and hard drives frequently use a cache, as do web browsers and web servers.
A cache is made up of a pool of entries. Each entry has a datum (a nugget (piece) of data) - a copy of the same datum in some backing store. Each entry also has a tag, which specifies the identity of the datum in the backing store of which the entry is a copy.


Read Only Memory.




ROM, which stands for Read only memory is another type of data storage. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to help with software  that are very closely tied to specific hardware. In most cases, data in ROM can hardly be changed. Moreover, this is a NON volatile memory, which means that when there is a power failure or shutdown, the information read or being used at that time is saved automatically and is not lost. Similarly, other types of non-volatile memories which usually refer to ROM is erasable programmable read only memory (EPROM) and electrically erasable programmable read only memory (EEPROM).

Flash Memory.



Flash memory is a non- volatile data storage chip that can be electrically erased and reprogrammed. It is most commonly used in memory cards, USB flash drives or 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 which is erased and programmed in large blocks; in early flash the entire chip has to erase at once. This was priced much less than byte-programmable EEPROM and therefore has become the dominant technology wherever a significant amount of non-volatile storage is needed. Flash memory stores information in an array of memory cells made from floating gate transistors. Flash memory is non-volatile, meaning no power is needed to maintain the information stored in the chip. In addition, flash memory offers fast read access times although not as fast as volatile DRAM memory used for main memory in PCs and better kinetic shock resistance than hard disk. In addition to this, flash memory is also durable, being able to withstand intense pressure, extremes of temperature, and even immersion in water.

Graphics card.




A video card, video adapter, graphics accelerator card, display adapter, or graphics card is an expansion card whose function is to generate output images to a display. Most video cards offer added functions, such as accelerated rendering of 3D scenes and 2D graphics, video capture, TV-tuner adapter, MPEG-2/MPEG-4 decoding, FireWire, light pen, TV output, or the ability to connect multiple monitors (multi monitors). Nowadays, they use it for gaming purposes. This graphics chip usually has a small quantity of embedded memory and takes some of the system's main RAM, reducing the total RAM available. This is usually called integrated graphics or on-board graphics, which is low-performance and is suggested inapplicable for those wishing to run 3D applications. A dedicated graphics card on the other hand has its own RAM and Processor specifically for processing video images, and thus offloads this work from the CPU and system RAM. There are different ways of measuring a graphics card, some of which are core clock speed, memory clock speed, pixel pipelines, textures per pipeline, and memory bandwidth.

Sound card.






Another type of computer expansion card is the sound card. It is an internal card that facilitates the input and output of audio signals to and from a computer under control of computer programs. The term sound card is also applied to external audio interfaces that use software to generate sound, as opposed to using hardware inside the PC. The most common usage of sound cards are for  providing the audio component for multimedia applications such as music composition, editing video or audio, presentation, education and entertainment (games) and video projection. In sound cards, they usually provide a digital to analog converter which converts the digital data generated into an analog format. There are various forms of sound cards. Some of which are Professional soundcards, Sound cards on other platforms (audio interfaces) and USB sound cards.



Network interface card.






 Often abbreviated as NIC, Network interface controller is a computer hardware component or an extension board that connects a computer to a computer network. Most of these are specially designed for types of networks like media and protocol, although some can serve additional networks. The purpose of this is that the controller uses the electronic circuitry needed to communicate using a specific physical layer and data link layer standard such as Ethernet, WI-FI or token ring which provides a base for a full network protocol stack, where by small groups of computers on the same Local area networks and large-scale network communications through routable protocols, such as Internet protocol are able to communicate.



Plug and play.






Plug and play usually refers to the characteristics of a computer bus or a device specification. This facilitates the discovery of a hardware component in a system, without the need for physical device configuration, or user intervention in resolving resource conflicts. Plug and play refers to both the boot-time assignment of device resources and to hotplug systems such as USB and firewire.In the beginnings of data processing technology, the hardware was just a collection of modules, and the functions of those modules had to be linked to accommodate different calculating operations. This linking was usually done by connecting some wires between modules and disconnecting others. For many mechanical data processing machines such as the IBM punched cards accounting machines, their calculating operations were directed by the use of a quick-swap control wired to route signals between module sockets. 



.U.S.B.






Universal Serial Bus , short for USB is a type of port which establishes communication between devices and a host controller (usually a personal computer), which has effectively replaced a variety of earlier interfaces such as serial and parallel port.

USB can connect different computer components such as mice, keyboards, digital cameras, printers, personal media, flash drives, Network Adapters, and external hard drives. For many of those devices, USB has become the standard connection method but the most common connection of a USB are the flash drives. There are millions of flash drives or USB with all sorts of memory capacity, shapes, colour and sizes. As of 2008, there are about 2 billion USB devices sold per year, and approximately 6 billion totals sold to date. Unlike the older connection standards RS-232 or parallel ports, USB connectors also supply electric power, so many devices connected by USB do not need a power source of their own.



Serial port.








A serial port usually refers to a serial communication physical interface through which data transfers in or out one bit at a time. In the previous days when PC was the highlight of the year, data transfer through serial ports connected the computer to devices such as terminals and various peripherals. It mainly analyzes hardwares manageable that are manageable to the RS-232 standard, intended to interface with a modem. Serial ports are still used in applications such as industrial automation systems, scientific instruments, shop till systems and some industrial and consumer products. Server computers may use a serial port as a control console for diagnostics. Network equipment (such as routers and switches) often use serial console for configuration. Moreover, serial ports are still being  used in these areas as they are cost efficient, easy to manage, widespread and their console functions are highly standardized, usually to prevent any errors in the system.





Parallel port.






A parallel interface for connecting an external device such as a printer. Most personal computers have both a parallel port and at least one serial port.
On PCs, the parallel port uses a 25-pin connector (type DB-25) and is used to connect printers, computers and other devices that need relatively high bandwidth. It is often called a Centronics interface after the company that designed the original standard for parallel communication between a computer and printer. The latest type of parallel port, which supports the same connectors as the Centronics interface, is the EPP (Enhanced Parallel Port) or ECP (Extended Capabilities Port). Both of these parallel ports support bi-directional communication and transfer rates ten times as fast as the Centronics port. In addition to this, these are some host of well known computer peripherals such as printers, scanners, CD burners and external hard drives.



Firewire port.






 Fire-wire ports are forms of a serial port that make use of FireWire technology to transfer data rapidly from one electronic device to another. It all started in 1995, when Apple, Inc. first began to include the port on a number of digital camcorders. Nowadays, the FireWire port is used on multiple devices.
As a multi-platform serial bus, the FireWire port has the ability to interact with a number of different devices. For example, a FireWire connection can provide an ideal way to connect a scanner to a computer system. Because the transfer rate of a FireWire port can reach up to 400 MBPS, the data transfer is relatively fast and also results in excellent quality.



Ethernet port.






An Ethernet port is an opening on computer network equipment that Ethernet cables plug into. These ports are alternatively called jacks or sockets. Ethernet ports accept cables with RJ-45 connectors. Moreover, It defines a number of wiring and signalling standards for the physical layer of the standard networking model as well as a common addressing format and a variety of medium access control procedures at the lower part of the data link layer. Besides that, Ethernet can also be used on various technological components such as computers, routers and computer electronic. In these modern days, it has been standardized to IEEE 802.3



.H.D.M.I.






HDMI utilizes the EIA/CEA-861 standards, which demonstrates video formats and waveforms, transport of compressed, uncompressed, and LPCM audio, auxiliary data, and implementations of the VESA EDED.HDMI supports, on a single cable, any uncompressed TV or PC video format, including standard, enhanced and HD-video up to 8 channels of compressed or uncompressed digital audio; a consumer electronics control (CEC) connection; and an Ethernet data connection.HDMI, short for High-Definition Multimedia Interface is a compact audio/video interface for transmitting uncompressed digital data.HDMI connects the digital. Audio sources, DVD players, HD DVD, Blu –ray disc, camcorders, personal computers, and video games console to compatible digital audio devices, computer monitors, TV and video projectors.