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Cable
Cable is the transmission medium of copper wire or optical fiber wrapped in a protective cover.
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Cache
Cache (Internet Browser) stores the files and graphics saved locally from web sites that have been previously
visited. Cache is a fast storage buffer in the central processing unit of a computer. In this sense, also called
cache memory .A cache temporarily stores the information on a page in your computer. If you request a page that
is stored in a cache, Browsers can retrieve the page from the cache more quickly than retrieving the page again
from it's location out on the network.
Sometimes you may not want a page to be retrieved from a cache. The page you brought initially may no longer be
identical to the page currently offered by the network. If a modification to a particular URL has occurred, you
may want the updated page rather than the copy (now stale) stored in a cache.
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Card
Cars ia a circuit board that usually is designed to plug into a connector or slot. See also adapter.
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Careware
Careware is software that is freely distributed via download. The only payment expected for careware, is the
user must care about something, anything, and show it in some way to better themselves or their community.
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CBT (Computer-Based Training)
Programs that provide interactive training sessions through some form of computer-based graphic presentation.
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CCITT (Comité Consultatif Internationale de Télégraphique et Téléphonique)
International association that once set worldwide communication standards (such as V.21, V.22, and X.25). Replaced
by the ITU-TSS.
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CE (Conformité Européenne)
The CE mark is a mandatory European marking for certain product groups to indicate conformity with the essential
health and safety requirements set out in European Directives. The letters 'CE' are an abbreviation of Conformité
Européenne, French for European conformity. A certification products must attain in order to be sold in
the European Union (EU) that involves complying with a number of different EU standards including strong resistance
to EMI/RFI as well as low EMI/RFI emissions.
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Cell
The smallest component of a table. In a table, a row or column contains one or more cells.
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CERT (Computer Emergency Response Team)
The CERT was formed by DARPA in November 1988 in response to the Internet worm incident. CERT exists to facilitate
Internet-wide response to computer security events involving Internet hosts and to conduct research targeted at
improving the security of existing systems. They maintain an archive of security-related issues on their FTP server
at "cert.org." Their email address is "cert@cert.org" and their 24-hour telephone 42-hour Hotline
for reporting Internet security issues is +1 412-268-7090.
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CGI (Common Gateway Interface)
CGI is the standard Web protocol for processing information that a user enters via a form. So, it is a standard
method of extending Web server functionality by executing programs or scripts on a Web server in response to Web
browser requests. A common use of CGI is in form processing, where the browser sends the form data to a CGI script
on the server, and the script integrates the data with a database and sends back a results page as HTML. CGI is
the standard for running programs on a server from a Web page.
Gateway programs, or scripts, are executable programs which can be run by themselves. They have been made external
programs in order to allow them to run under various (possibly very different) information servers interchangably.
Gateways conforming to this specification can be written in any language which produces an executable file. Some
of the more popular languages to use include: C or C++, Perl, Python, TCL, shells, and many others. Some of the
most common CGI scripts found on the Web are programs which process the information a user might enter on a form
or whenever an imagemap is "clicked" on - although most imagemaps these days are done via a client side
script which resides in the HTML file itself.
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CHAP (Challenge-Handshake Authentication Protocol)
An authentication method that can be used when connecting to an Internet Service Provider. CHAP allows you
to login to your provider automatically, without the need for a terminal screen. It is more secure than the Password
Authentication Protocol (another widely used authentication method) since it does not send passwords in text format.
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Chat
Another term for IRC . Also, an acronym meaning "Conversational Hypertext Access Technology".
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Check box
A form field that can be chosen by clicking a box. When a box is selected, it is usually displayed with a check
mark or X. Check boxes are usually grouped to represent a set of choices. Users can select more than one check
box in a form. See also radio button.
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Client
On the Internet, a program that requests files or services from a server. Client refers to an application, usually
on a desktop computer, that connects to a server. Opposite of server.
In Internet terms, it's an application that performs a specific function, such as Telnet or FTP. It's the "front-end"
to an Internet process. In more general terms, a client is computer system or process that requests a service of
another computer system or process. The much talked about "client-server architecture" refers to a workstation
requesting the contents of a file from a server.
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Client / Server
Client/Server is a networking system in which one or more file servers (Server) provide services; such as network
management, application and centralized data storage for workstations (Clients).
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Client-side image map
An image map that encodes the destination URL of each hotspot directly in a page. Client-side image maps do not
require processing from a server to follow the hyperlinks on the image map, so they are more efficient. However,
not all browsers support client-side image maps.
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Clock Cycle
The smallest unit of time required for a computer to perform individual operations. For example, it takes one clock
cycle for the CPU to transfer data between two of its registers. A clock cycle is also called a "CPU cycle"
or a "clock tick".
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Cluster
The basic allocation unit of magnetic disks storage. Windows allocates space to files in units called clusters.
Each cluster contains from 1 to 64 sectors, depending on the type and size of the disk. A cluster is the smallest
unit of disk space that can be allocated for use by files. Clusters (also known as allocation units) consist of
one or more disk sectors. Because storage space is allocated based on clusters, even if a file (or part of a file)
physically occupies only a portion of a cluster, that entire cluster will be allocated to the file, and will be
considered used disk space. Since file sizes are only rarely exact multiples of the cluster size, the last cluster
storing the file's data usually includes some empty space called "slack space" at the end. Clusters make
it possible for the operating system to manage the files on a disk more effectively than it could if it had to
work at the sector level. Each CLUSTER holds only one file. 1GB hard disk partioned with FAT16 has the cluster
size of 16KB (1KB file will therefore take-up 16KB, wasting 15KB of hard disk space).
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CMOS (Complimentary Metal Oxide Semiconductor)
A part of the motherboard that maintains system variables in static RAM. It also supplies a real-time clock that
keeps track of the date, day and time. CMOS Setup is typically accessible by entering a specific sequence of keystrokes
during the POST at system start-up. So, CMOS ia a type of semiconductor designed to require very little power.
Although CMOS-based memory is volatile, the stored information can be maintained by connecting the CMOS chip to
a small power source, such as a battery.PCs use CMOS memory chips to preserve basic data about system hardware.
Information such as the number and types of disks, amount of RAM, and type of keyboard is stored in the PC’s CMOS
memory. This information appears on the computer’s "setup screen" which can usually be displayed during
startup.If the battery powering the CMOS memory fails, the information is lost, which can result in problems starting
the computer.
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Coaxial Cable
Coaxial Cable is a cable consisting of a single copper conductor in the center surrounded by a plastic layer for
insulation and a braided metal outer shield.
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Cold Boot
Starting or restarting a computer by turning on the power supply. See also warm boot.
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Column
In a table, a vertical collection of cells.
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Compile
To translate (a program) into machine language.
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Compiler
A program that translates another program written in a high-level language into machine language so that it can
be executed.
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Composite Link
The line or circuit connecting a pair of multiplexors or concentrators; the circuit carrying multiplexed data.
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Composite Video
The video-only (no audio) part of a TV signal that mixes red, green, blue, and sync signals.
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Concentrator
Concentrator is a device that provides a central connection point for cables from workstations, servers, and peripherals.
Most concentrators contain the ability to amplify the electrical signal they receive.
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CONFIG.SYS
For Windows 9x: A text file containing commands that configure a system’s hardware and load device drivers automatically
when the computer starts up. Many of the functions traditionally performed by this file have been built into current
versions of Windows. The primary remaining purpose of the CONFIG.SYS file now is to load real-mode device drivers
for which no virtual device driver counterparts are available. Together with the AUTOEXEC.BAT file, CONFIG.SYS
affects the environment used for all DOS VMs, and so for all MS-DOS applications run under Windows. Windows 9x
processes the CONFIG.SYS file (if any) during system startup.
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Contention
The facility provided by the dialup network or a data PABX that enables multiple terminals to compete on a first-come,
first-served basis for a smaller number of computer ports.
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Context Menu
Also called a context-sensitive menu, or a shortcut menu, a context menu includes the commands that are commonly
associated with an object on the screen. To activate an item's context menu, point to it with the screen pointer,
then press and release the right mouse button once.
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Cookie
Internet Browser cookies hold information on the times and dates when visited web sites. Other information
can also be saved to your hard disk in these text files, including information about online purchases, validation
information about you for members-only web sites, and more. So, a cookie is a special piece of information about
you, something you clicked on, and/or your computer system which is stored in a text file on your hard drive. This
information is usually accessed by a server when you connect to a Web site which wants to know some information
about you or your system. One common occurance of a "handing of a cookie", would be when you as a user,
log into a system through a Web site. After you enter in your username and password, a text file is saved by your
browser for later access. This prevents you from having to log in again if you happen to leave the Web site and
then return at a later time. Cookies are also used in the process of purchasing items on the Web. It is because
of the cookie, that the "shopping cart" technology works. By saving in a text file, the name, and other
important information about an item a user "clicks" on as they move through a shopping Web site, a user
can later go to an order form, and see all the items they selected, ready for quick and easy processing. Afterall,
why have a cookie as nowadays cookies are used also as malicious tracking tools.
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CPU (Central Processing Unit)
CPU stands for Central Processing Unit, a programmable logic device that performs all the instruction, logic, and
mathematical processing in a computer. So, CPU is the portion of a computer that performs computations, executes
instructions and transfers information between all parts of the computer. Microcomputers such as PCs contain single-chip
central processing units, called microprocessors.
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Crash
Crash is a sudden, usually drastic failure. Can be said of the operating system or a particular program when
there is a software failure. Also, a disk drive can crash because of hardware failure.
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CRC (Cyclic Redundancy Check)
An error-checking procedure for data transmission. The sending device performs a complex calculation, generating
a number based upon the data being transmitted, and sends that number to the receiving device. The receiving device
performs the same calculation after transmission. If the results match, the transmission succeeds. If the numbers
don't match, it means the message was received in an altered state, and the data may be incorrect.
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Cross-linked files
Two files that both refer to the same data. As modern file systems are used and files are deleted and created,
the total free space becomes split into smaller non-contiguous blocks. Eventually new files being created, and
old files being extended, cannot be stored each in a single contiguous block but become scattered across the file
system. This degrades performance as multiple seek operations are required to access a single fragmented file.
So, it is an error condition in which the FAT indicates that data from two different files occupies the same cluster
on a disk. A cluster can contain data for only one file, so cross-linked files indicate an error in the disk’s
file structure. Norton Disk Doctor can determine the true owner of the data and correct this type of error.
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Crossed Pinning
A cable configuration that enables two DTE or two DCE devices to communicate.
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Crossover
A conductor that runs through the cable and connects to a different pin number at each end.
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CSMA/CA (Carrier Sense Multiple Access Collision Avoidance)
CSMA/CA is a network access method in which each device signals its intent to transmit before it actually does
so. This prevents other devices from sending information, thus preventing collisions from occurring between signals
from two or more devices. This is the access method used by LocalTalk.
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CSMA/CD (Carrier Sense Multiple Access Collision Detection)
CSMA/CD is a network access method in which devices that are ready to transmit data first check the channel
for a carrier. If no carrier is sensed, a device can transmit. If two devices transmit at once, a collision occurs
and each computer backs off and waits a random amount of time before attempting to retransmit. This is the access
method used by Ethernet.
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CSU (Channel Service Unit)
A digital DCE used to terminate digital circuits (such as DDS or T1 lines) at the customer site. It performs
line coding, line conditioning, and equalization functions and responds to loopback commands sent from the central
office.
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Current Loop
A method of interconnecting terminals and transmitting signals in which a mark (binary 1) is represented by
current on the line, and a space (binary 0) is represented by the absence of current.
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Cyberspace
The "world of computers and the society that gathers around them", as referred to by William Gibson
in his fantasy novel "Neuromancer". It now loosely refers to the online world and even more loosely to
the Internet.
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