Communication and Network

Modulation


An earlier magnetic disk encoding method that places clock bits onto the medium along with the data bits. It was superseded by MFM and RLL. Varying the frequency of the waves of a carrier in order to transmit analog or digital data. Frequency modulation (FM) is widely used in audio transmission, not only for its namesake FM radio, but for the audio channels in television.

Demodulation

To isolate a data signal from a carrier wave. The demodulation circuit uses the unmodulated carrier as a reference signal and compares it to the received signal.

Bandwidth

The term bandwidth has a number of technical meanings but since the popularization of the Internet, it has generally referred to the volume of information per unit of time that a transmission medium (like an Internet connection) can handle.

TCP/IP
(Transmission Control Protocol/Internet Protocol) A communications protocol developed under contract from the U.S. Department of Defense to internetwork dissimilar systems. Invented by Vinton Cerf and Bob Kahn, this de facto Unix standard is the protocol of the Internet and the global standard for local area networks and wide area networks, the major exception being the traditional networks of the telephone companies.

Node

In a communications system, a node is a network junction or connection point. Every terminal, computer, hub and switch is a node. In database management, a node is an item of data that can be accessed by two or more routes. In computer graphics, a node is an endpoint of a graphical element. In the Document Object Model (DOM), which exposes HTML and XML content to an application or script, every element, every attribute of that element, and each piece of textual content for every attribute is considered a node.

Client
An architecture in which the user's PC (the client) is the requesting machine and the server is the supplying machine, both of which are connected via a local area network (LAN) or a wide area network (WAN) such as the Internet. Throughout the late 1980s and early 1990s, client/server was the hot buzzword as applications were migrated from minicomputers and mainframes with input/output terminals to networks of desktop computers.

Server

A computer that runs a Web site. Using the HTTP protocol, the Web server delivers Web pages to browsers as well as other data files to Web-based applications. The Web server includes the hardware, operating system, Web server software, TCP/IP protocols and site content (Web pages, images and other files). If the Web server is used internally and is not exposed to the public, it is an "intranet server"

Network operating System

An operating system that is designed for network use. Normally, it is a complete operating system with file, task and job management; however, with some earlier products, it was a separate component that ran under the OS; for example, LAN Server required OS/2, and LANtastic required DOS.

Server

Unix, Linux, NetWare, Windows 2000 Server and Windows Server 2003 are examples of network operating systems designed for use in stand-alone servers. Such products may also include a Web server, directory services, messaging system, network management and multiprotocol routing capabilities.

Network Administrator

A person who manages a local area communications network (LAN) or wide area network (WAN) for an organization. Responsibilities include network security, installing new hardware and applications, monitoring software upgrades and daily activity, enforcing licensing agreements, developing a storage management program and providing for routine backups, not to mention ensuring that it is up and running all the time.

Secondary Storage

Disk Caching



To store data locally in order to speed up subsequent retrievals. Reserved areas of memory in every computer that are used to speed up instruction execution, data retrieval and data updating. Pronounced "cash," they serve as staging areas, and their contents are constantly changing. There are two kinds: memory caches and disk caches.

File Compression

Encoding data to take up less storage space and less bandwidth for transmission. Digital data are compressed by finding repeatable patterns of binary 0s and 1s. The more patterns can be found, the more the data can be compressed. Text can typically be compressed to approximately 40% of its original size, and graphics files from 20% to 90%. Some files compress very little. It depends entirely on the type of file and compression algorithm used.

File Decompression

Data compression is the encoding of data to consume less space and bandwidth. Data decompression is the reverse--the decoding of compressed data to restore the original data. Compression/decompression algorithms look for redundancies in data, then minimize them using predetermined algorithms (methods). There are different algorithms used to achieve different compression rates.

Internet Hard Drive
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. Similar to depositing money into your bank account, and later withdrawing that same money from any ATM machine, 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 Disk Drive

A direct access storage device that is written and read by light. The most common optical discs in use are CDs and DVDs, and they come in three types: read-only, write-once and rewritable. CD, CD-ROM, DVD-ROM, DVD-Video as well as BD-ROM (Blu-ray) are read-only discs that are recorded at the time of manufacture and cannot be erased. CD-R, DVD-R, DVD+R, BD-R, WORM and magneto-optic (in WORM mode) discs are write-once. They are recorded in the user's environment, but cannot be erased. CD-RW, DVD-RAM, DVD-RW, DVD+RW, BD-RE and MO discs are rewritable.

Solid-state Storage



Non mechanical. Solid state refers to electronic circuits composed of transistors, resistors, capacitors and other components, which may be discrete, single devices, or millions of them can be created in a single chip. For example, microprocessors and memories are all solid state. In a solid state device, there is no mechanical action, although an unbelievable amount of electromagnetic action takes place within.

A computer has solid state and non-solid state parts. The solid state components are the motherboard, chips, screen, camera and optical mouse, while the hard drive, CD/DVD drive, fans, keyboard, microphone, speakers and mechanical mouse are both electronic and mechanical and thus not solid state.

Input and Output

Ergonomic Keyboard

A keyboard that separates the keys into two halves shaped like a wide "V." Some keyboards have a fixed layout, while others are movable. To the touch typist, the layout feels odd at first, but it puts less stress on the hands and wrist and winds up being comfortable for most people.

Inkjet Printer

A printer that propels droplets of ink directly onto the medium. Today, almost all inkjet printers produce color. Low-end inkjets use three ink colors (cyan, magenta and yellow), but produce a composite black that is often muddy. Four-color inkjets (CMYK) use black ink for pure black printing. Inkjet printers run the gamut from less than a hundred to a couple hundred dollars for home use to tens of thousands of dollars for commercial poster printers.

Laser Printer

A laser printer is a printer that uses a focused beam or light to transfer text and images onto paper. Though contrary to popular belief, the laser does not actually burn the images onto the paper. Instead, as paper passes through the printer, the laser beam fires at the surface of a cylindrical drum called a photoreceptor. This drum has an electrical charge (typically positive), that is reversed in areas where the laser beam hits it. By reversing the charge in certain areas of the drum, the laser beam can print patterns (such as text and pictures) onto the photoreceptor.

Magnetic-Ink Character Recognition

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 printed documents. Unlike barcodes or similar technologies, however, MICR codes can be easily read by humans.

Optical-Character Recognition

The machine recognition of printed characters. OCR systems can recognize many different OCR fonts, as well as typewriter and computer-printed characters. Advanced OCR systems can recognize hand printing.

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.

SYSTEM UNIT

RAM

It is a type of computer memory that provides direct access to any single location (any byte). RAM chips are "byte addressable." The contents of any byte can be read or written without regard to the bytes before or after it. The term generally refers to main memory, which is the computer's workspace, and the most common type of RAM is the DRAM chip. RAM read and write speeds are generally the same, taking no longer to write a byte than it does to read one.

CACHE MEMORY

Cache is the small amount of memory that is normally less then 1MB that resides on the CPU so that the time to access the main memory is reduced. Cache memory stores the copies of the most frequently used data and when the user requests to access a certain portion of the maim memory, the computer will check cache memory first and load it immediately if it is resent in the cache memory thereby reducing the access time. If it is not present in cache then it will load from the main memory and this involves latency.

ROM

Form of computer memory that does not lose its contents when the power supply is cut off and that is not rewritable once it is manufactured or written. It is generally employed for programs designed for repeated use without modification, such as the start-up procedures of a pc, the ROM is used for storing the program used in the control unit of the computer.

FLASH MEMORY

A very popular non-volatile, rewritable memory chip used for storage. Extremely durable, flash memory is used in myriad portable devices, including digital cameras, digital music players, smartphones and tablet computers. USB drives "are" flash memory chips, and the solid state drives (SSDs), which are increasingly replacing hard disks in laptops, are also flash memory chips.

GRAPHIC CARD

Graphics cards are PCBs (printed circuit boards) that perform the dual role of sending pixels to the display and providing a specific type of processing using a GPU (graphical processing unit).
One of the main features of a graphics card is the ability to draw 3D graphics in realtime using a technique called rasterization. This involves converting 3D coordinates into areas of pixels and filling the areas with either a transformed image called a texture or a flat surface.

Most graphics cards can perform a technique called "Hardware Transform and Lighting", which means the 3D movement and illumination of triangle surfaces is handled by the card rather than using the CPU and making frequent use of buses.
A more recent addition to the capabilities of graphics cards is shader processing, which allows a game programmer to write special programs called shaders that have control over the way the GPU transforms coordinates and images.

When buying a graphics card, common indications of performance are triangles per second, texture fill rate, shader cores, GPU clock speed and memory clock speed. Other attributes that are likely to dictate which card to buy are form factor and power consumption.
Graphics cards follow standard interfaces, such as PCI-E, PCI or AGP, meaning they are common attachments for desktop computer motherboards.

SOUND CARD

Also called a "sound board" or "audio adapter," it is a plug-in card that records and plays back sound. Supporting both digital audio and MIDI, sound cards provide an input port for a microphone or other sound source and output ports to speakers and amplifiers. Sound circuits are typically built into the chipset on the motherboard, but can be disabled if a separate sound card is installed.

Digital audio files contain soundwaves converted into digital form. Sound cards convert the digital samples back into analog waves for the speakers using digital signal processing (DSP).

MIDI files contain a coded representation of the notes of musical instruments such as middle C on the piano. Taking considerably less space than digital audio, MIDI files require a wavetable synthesizer on the card, which holds digitized samples of the instruments.

NETWORK INTERFACE CARD

Pronounced "nick," this is the card that physically makes the connection between the computer and the network cable. These cards typically use an Ethernet connection and are available in 10, 100, and 1000 Base-T configurations. A 100 Base-T card can transfer data at 100 Mbps. The cards come in ISA and PCI versions and are made by companies like 3Com and LinkSys. So if you want to connect your computer to a network, you better get yourself a NIC.

PLUG AND PLAY

The ability to add a new component to a system and have it work automatically without having to do any technical analysis or manual configuration. A standard from Intel for peripheral expansion on a PC. On starting up the computer, Plug and Play (PnP) recognizes the attached peripheral devices and adjusts the appropriate internal settings, namely configuring the IRQ, DMA and I/O address.

SERIAL PORT

The serial port is a type of connection on PCs that is used for peripherals such as mice, gaming controllers, modems, and older printers. It is sometimes called a COM port or an RS-232 port, which is its technical name. If that's not enough to confuse you, there are two types of serial ports -- DB9 and DB25. DB9 is a 9-pin connection, and DB25 is, you guessed it, a 25-pin connection.

A serial port can only transmit one bit of data at a time, whereas a parallel port can transmit many bits at once. The serial port is typically the slowest port you'll find on a PC, if you find one at all. Most newer computers have replaced serial ports with much faster and more compatible USB ports.

PARALLEL PORT

A hardware interface that transfers one or more bytes simultaneously. A socket on a computer used to connect a printer or other device via a parallel interface (eight data bits transferring simultaneously). In the past, the parallel port was widely used for printers and occasionally for connecting other devices externally, but was superseded by USB.

UNIVERSAL SERIAL BUS PORT (USB)

The most widely used hardware interface for attaching peripherals to a computer. There are typically at least two USB ports on laptops and four on desktop computers, while USB "hubs" allow many more connections (see below). After appearing on PCs in 1997, USB quickly became popular for connecting keyboards, mice, printers and hard drives, eventually replacing the PC's serial and parallel ports.

USB devices are "hot swappable;" they can be plugged in and unplugged while the computer is on. This feature, combined with easy-to-reach ports on the front of the computer case, gave rise to the ubiquitous flash drive for backup and data transport

FIREWALL PORT

A firewall port, directly relates to an IP port. Sometimes you will need to ‘open a port’ in your firewall protection or router for a program to operate. Most programmers these days are aware that people use firewalls and routers so they try to make their software fully compatible with them. There are occasionally still programs that need some manual configuration. This is most often the case when you try to run a ‘server’ on your home network. Some of the most common servers that people like to run are game servers.

ETHERNET PORT

it's the same thing as a network port. looks like a telephone jack, but bigger. should be in the back of the system, and will probably have a symbol above it that looks like 3 boxes with lines connecting them.

HIGH DEFINITION MULTIMEDIA INTERFACE

It is a specification that combines video and audio into a single digital interface for use with digital versatile disc (DVD) players, digital television (DVT) players, set-top boxes, and other audiovisual devices. The basis for HDMI is High Bandwidth Digital Content Protection (HDCP) and the core technology of Digital Visual Interface (DVI). HDCP is an Intel specification used to protect digital content transmitted and received by DVI-compliant displays.

Basic and Specialized Software Application

Graphical user interface


The common method of interacting with a computer that allows any graphics image to be displayed on screen. Except for entering text on the keyboard, the primary way the computer is operated is with a mouse or touchpad pointing device. The mouse/touchpad is used to select icons and menu options as well as move and resize windows that frame the application and elements within it. The major GUIs are Windows and Mac along with GNOME and KDE for Linux.

Word processor


The creation of text documents. Except for labels and envelopes, it has replaced the electric typewriter in most offices, because of the ease in which documents can be edited, searched and reprinted.

Advanced word processors function as elementary desktop publishing systems. Although there are still machines dedicated only to word processing, most word processing is performed on general-purpose computers using word processing software such as Microsoft Word and WordPerfect.

Spreadsheet


Software that simulates a paper spreadsheet (worksheet), in which columns of numbers are summed for budgets and plans. It appears on screen as a matrix of rows and columns, the intersections of which are called "cells." The cells are filled with (1) labels, (2) numeric values or (3) formulas.

Labels are descriptive text such as "Rent" and "Gross Sales." Values are the actual numeric data, and formulas command the spreadsheet to do the calculations; for example, SUM CELLS A5 TO A10.

DBMS


(DataBase Management System) Software that controls the organization, storage, retrieval, security and integrity of data in a database. It accepts requests from the application and instructs the operating system to transfer the appropriate data. The major DBMS vendors are Oracle, IBM, Microsoft and Sybase (see Oracle database, DB2, SQL Server and ASE). MySQL is a very popular open source product (see MySQL).

DBMSs let information systems be changed more easily as the organization's requirements change. New categories of data can be added to the database without disruption to the existing system. Adding a field to a record does not require changing any of the programs that do not use the data in that new field.

Utility suites


is a kind of system software designed to help analyze, configure, optimize and maintain the computer which allows users to do things like creating text documents, playing games, listening to music or surfing the web. Due to this focus, utilities are often rather technical and targeted at people with an advanced level of computer knowledge.

Web authoring


A category of software that enables the user to develop a Web site in a desktop publishing format. The software will generate the required HTML coding for the layout of the Web pages based on what the user designs. Typically, the user can toggle back and forth between the graphical design and the HTML code and make changes to the Web page in either the design of the accompanying code.

To design and create a Web site, from writing the site's underlying code to writing the text to managing the site's upkeep.

Audio editing software



A digital audio editor is a computer application for audio editing, i.e. manipulating digital audio. Digital audio editors are the main software component of a digital audio workstation.

Bitmap image


bitmap or pixmap is a type of memory organization or image file format used to store digital images. The term bitmap comes from the computer programming terminology, meaning just a map of bits, a spatially mapped array of bits. Now, along with pixmap, it commonly refers to the similar concept of a spatially mapped array of pixels. Raster images in general may be referred to as bitmaps or pixmaps, whether synthetic or photographic, in files or memory.

In certain contexts, the term bitmap implies one bit per pixel, while pixmap is used for images with multiple bits per pixel

Desktop publishing program


system for producing printed materials that consists of a personal computer personal computer (PC), small but powerful computer primarily used in an office or home without the need to be connected to a larger computer. PCs evolved after the development of the microprocessor made possible the hobby-computer movement of the late 1970s, when or computer workstation, a high-resolution printer printer, computer output device that reproduces data on paper or another medium. Impact printers use a mechanical hammering device to produce each character.
(usually a laser printer), and a computer program computer program, a series of instructions that a computer can interpret and execute; programs are also called software to distinguish them from hardware, the physical equipment used in data processing that allows the user to select from a variety of type fonts and sizes, column justifications, page layouts, and graphics libraries and often includes support for document creation and editing. Desktop publishing enables a small business or an individual to produce professional-quality materials on the premises inexpensively and quickly without the need for outside typesetting or printing facilities.

HTML editor


A low-level Web site authoring tool that is essentially a text editor, specialized for writing HTML code. It assists the HTML author by cataloging all HTML tags and common structures in menus and by being able to catch certain syntax errors. It often displays tags and contents in colors so they pop out for easy reference.

Image editor


Software that allows images to be edited and also converted to different graphics formats. Image editors typically deal with only bitmapped images such as GIFs, JPEGs and BMPs; however, some editors support both bitmaps and illustrations. Common functions are manually cropping and resizing the image and using "filters" to adjust brightness, contrast and colors. A myriad of filters are available for special effects. Red eye removal is included in editors specialized for photos.

Multimedia


As the name implies, multimedia is the integration of multiple forms of media. This includes text, graphics, audio, video, etc. For example, a presentation involving audio and video clips would be considered a "multimedia presentation." Educational software that involves animations, sound, and text is called "multimedia software." CDs and DVDs are often considered to be "multimedia formats" since they can store a lot of data and most forms of multimedia require a lot of disk space.

Vector image


Unlike JPEGs, GIFs, and BMP images, vector graphics are not made up of a grid of pixels. Instead, vector graphics are comprised of paths, which are defined by a start and end point, along with other points, curves, and angles along the way. A path can be a line, a square, a triangle, or a curvy shape. These paths can be used to create simple drawings or complex diagrams. Paths are even used to define the characters of specific typefaces.

Because vector-based images are not made up of a specific number of dots, they can be scaled to a larger size and not lose any image quality. If you blow up a raster graphic, it will look blocky, or "pixelated." When you blow up a vector graphic, the edges of each object within the graphic stay smooth and clean. This makes vector graphics ideal for logos, which can be small enough to appear on a business card, but can also be scaled to fill a billboard. Common types of vector graphics include Adobe Illustrator, Macromedia Freehand, and EPS files. Many Flash animations also use vector graphics, since they scale better and typically take up less space than bitmap images.