Sunday 26 June 2011

Communication And Network

Modulation








Modulation is the process of transmitting information or signal to an electronic or optical signal carrier. It can be used to direct current, alternating current and also optical signals. 






Demodulation








Demodulation is the opposite of modulation. It is the process of taking out the original information-bearing signal from a modulated carrier wave. It is an electronic circuit which is used to bring back information content from the modulated carrier wave.






Bandwidth






Bandwidth has two or more meaning. In computer networks, it is the amount of data which can be carried from one point to the another in a given time period which is usually in a second. It is usually expressed in bits of data per second.  On the other hand, in electronic communication, bandwidth is the width of the range of frequencies that an electronic signal uses on a given transmission medium. 






TCP/IP










TCP/IP which stands for Transmission Control Protocol/Internet Protocol is the fundamental communication language or protocol of the Internet. Besides that, it can also be used as a communication protocol in a private network either is an intranet or an extranet. 




Node






A node is a connection point, it can either be a redistribution point or an end point for data transmissions. Basically, it has programmed or engineered capability to process and recognize or forward transmission to another nodes.  




Client






A client is a type of requesting program or user in a client/server relationship. For instance, a user of a Web browser is successfully making client request for pages from servers all over the Web. This makes the browser itself is a client in its relationship with the computer that is getting and returning the requested HTML file. 




Server





A network server is a type of computer that is built and designed to process requests and send data to another client computers over a local network or the Internet.



Network Operating Systems






A network operating system is a computer operating system's that is created primarily to support workstation, personal computer and some older terminal that are connected on a local area network (LAN). It also provide printer sharing,application sharing, and also the ability to make the network manage name directory, security and many more.






Network Administrator


A network administrator is in charge of maintaining an organization's local area network. It connects computers and other equipment that shares the same communications line of network server.

Saturday 18 June 2011

Secondary Storage

Disk Caching




Disc Caching is a process where portion of RAM which is used to speed up the access to data on a disk. The RAM cab also be a part of the disk drive itself which is sometimes called a hard disk cache or buffer. It can also be a general-purpose RAM in the computer that is reserved for use by the disk drive. Hard disk caches are more effective,but are much more expensive, and smaller.





File Compression



File compression is often used when sending a file from one computer to another by a connection that has limited bandwidth. It makes the file smaller which makes the sending of the file faster. When compressing a file and sending it to another computer that computer has to have a program that will decompress the file so that it can go back to being normal and used.




File Decompression



File Decompression is the encoding of data so that they can consume less space and bandwidth. It is the reverse of decoding of compressed data to restore the original data.


Internet Hard Drive



An Internet Hard Drive enables the user to access computer files such as pictures, documents or music from any computer as long as they are connected to the Internet. Internet hard drive allow you to save your computer files into a remote hard drive and then later access those very same files from any other computers.



Optical DISC Drive

An optical DISC drive is a storage medium from which data is read and written by lasers. It can store much more data which is up to 6 gigabytes than most portable magnetic media such as floppies.



Solid-state Storage




A solid-state storage is a nonvolatile and removable storage medium that employs integrated circuits rather than magnetic or optical media such as flash memory Universal Serial Bus(USB) devices and various propriety removable packages that is intended to replace external hard drives.

Wednesday 15 June 2011

Input and Output

Ergonomic Keyboard




An ergonomic keyboard ia a type of keyboard that is designed with the ergonomic considerations to help minimize music strain and many other related problems.



Inkjet printer



An inkjet printer is a type of printer that makes a digital image by propelling droplets of ink onto the paper. It is one of the most commonly used type of printer.



Laser printer



The laser printer is the well known type of personal computer printer that uses a non-impact photocopier technology. After a document was sent to the printer, a laser beam "draws" the document on a selenium-coated drum using electrical charges. After that, the drum that is fully charged will be rolled in  a toner, a dry powder type of ink. The toner will then adheres to the charged image on the drum. The toner is then transferred onto a piece of paper and fused to the paper with heat and pressure. Most laser printers print only in monochrome.


Magnetic-Ink Character Recognition




A magnetic ink character recognition (MICR) is a type of a character recognition technology used by the banking industry to help the processing of cheques. It allows computers to read information such as the account numbers off printed documents. MICR codes can be easily read by the humans.



Optical-character recognition






The optical character recognition (OCR) is the recognition of printed or written text characters by a computer that involves photo scanning of the text character-by-character, analysis of the scanned-in image and also the translation of the character image into character codes such as ASCII which is commonly used in data processing.






Optical-Mark Recognition


An optical mark recognition (OMR) is the process of capturing human-marked data from document forms such as surveys and tests.


Saturday 4 June 2011

System Unit

RAM


RAM or Random Access Memory take place in the computer's operating system,application programs, and data in current use are kept so that they can be quickly approached by the computer's processor. It is much faster and easier to read from and write to than the other kinds of storage in a computer, floppy disks and CD-ROM. However, the data in RAM stays there until your computer stops running. It will loses its data when the computer is turned off.



Cache Memory


Cache memory is random access memory or RAM that a computer microprocessor can access faster than it can access regular RAM. While the microprocessor processes data, it will look first in the cache memory and if it finds the data there, it will not be time consuming reading of data from bigger memory. It is also described in level of closeness and accessibility to the microprocessor.



ROM





ROM or Read Only Memory retains stored information even when the computer is turned off. It is normally used for storing programs and data that need not be change once stored. The processor uses ROM to store and execute programs instructions.



Flash memory



Flash memory, sometimes known as the flash RAM is a type of constantly-powered nonvolatile memory that can be erased and reprogrammed in units of memory called blocks. It is a alternative of EEPROM or electrically erasable programmable read -only memory. Flash memory is often used to hold control code such as the basic input/output system (BIOS) in a personal computer. It is used in digital cellular phones, digital cameras, LAN switches, PC cards for notebook computer,embedded controllers and other devices.





Graphic Card





A graphic card is a display adapter which is installed inside of a computer and works to display images on the monitor. Its job is to display images on the computer's monitor. Information is then communicated from the computer's  CPU (Central Processing Unit) to the graphic card. The information that is transmitted is converted into a picture that the computer's user can understand.



Sound card



A sound card is an expansion board which enables the computer to manipulate and output sound. It is necessary for almost all CD-ROMs and have become commonplace on modern personal computers. Sound cards enables the computer to output sound through speakers connected to the board,to record sound input from a microphone connected to the computer and then manipulate sound stored on a disk.



Network Interface Card



Network Interface Card is a device that allows computers to be joined together in a LAN or local area network. Network interface card provide a dedicated,full-time connection to a network.


Plug and play



Plug and play is a technology that allows the operating system that gives the users the ability to plug a device into a computer and have the computer recognize that the device is there. There is no need for the user to tell the computer.




Serial Port



Serial Port is a connector by which a device that sends data one bit at a time and may be connected to a computer.


Parallel Port



A parallel port is a interface that connects an external device such as a printer. It uses the 25 pin connector and is used to connect printers,computers and other devices that need relatively high bandwidth. A parallel port is a port straight away from the main bus system in the computer.




Universal Serial Bus Port (USB) is a commonly used hardware interface for attaching peripherals to the computer. There are at least two USB ports on laptops and four on desktop computers,while USB "hubs" allow many more connections. They can be plugged in and unplugged while the computer is on.




Firewire port





Firewire port is a serial bus that was created by Apple via IEEE 1394 which is a high performance serial bus for connecting devices to the personal computer. It provides a single plug-and-socket connection on which up to 3 devices that can be attached with data transfer speeds up to 400 Mbps.




Ethernet Port



Ethernet Port is a socket on a computer or network devices to plug in an Ethernet Port.

High Definition Multimedia Interface



High Definition Multimedia Interface is a audio connection system and digital video which is used to connect a variety of audio/video (HDTV). It supports all HDTV formats and it supports for up to eight channels of digital audio.