Glossary - C        A B C  D E F G H I J K L M N O P Q R S T U V W X

Carriage Return (CR) - A control character (ASCII: 13) specifying that the next character is to be displayed at the leftmost position of the current line. In older mechanical character printing devices the carriage was moved to cause printing in different character positions of the same line. In a PC the CR code is generated by pressing the Enter key on the keyboard, and stored in most text files at the end of each line. See also ASCII, End of Line.

CD-ROM File System (CDFS) - The file system which supports CD-ROM / CD-RW drives.

Central Processing Unit (CPU) - The part of the computer which historically performed all logic and most calculations. In PC-compatible systems, the CPU is on a single microprocessor chip. Many high-performance computers, including PCs, have more than one processing unit, often organized in such a way that none qualifies as the "central" processing unit.

Character Code - The code representing a specific character in the computer. See also: ASCII, Code Page, Unicode.

Character Device - A physical device for input or output which must communicate with your computer one character at a time. Examples include the console, communications ports, and printers. See also Block Device.

Character Mode - A display mode in which output is displayed one character at a time, and which cannot display graphics or pictures not included in the character font used. Character Mode displays are usually in a fixed font, typically with 80 columns in a line and 25 lines on the screen. Some systems allow you to increase or decrease the number of rows and columns to other fixed sizes. See also Graphic Mode.

CMD File - A batch file designed for execution by CMD.EXE or TCC.

CMDLINE - An environment variable used to extend the command line passed to another program beyond its normal length limits.

Code Page - A setting which tells Windows which character set to use, and how to retrieve and display date, time, and other information in the format appropriate to a particular country or region. See also Country Settings.

Cold Boot - The process of starting the computer by turning on its power. See also Boot, Cold Reboot, Reboot, Warm Reboot..

Cold Reboot - The process of restarting the computer in a way that physically resets most hardware devices, typically by pressing a reset button, or by emulating it utilizing a special feature of the BIOS. See also Boot, Cold Boot, Reboot, Warm Reboot.

Command Completion - A TCCfeature which allows you to recall a previous command by typing the first few letters of the command, then an up-arrow or down-arrow.

Command Echoing - A TCC feature which displays commands as they are executed. Echoing can be turned on and off.

Command Grouping - A TCC feature which allows you enclose a group of several commands within parentheses, and have them treated as a single command.

Command History - A TCC feature which retains the commands you have executed from the command prompt, so that they can be recalled, optionally modified, and reexecuted later.

Command History Window - A pop-up window used by TCCto display the command history, allowing you to choose a previous command to modify and/or execute.

Command Interpreter - Same as Command Processor.

Command Line Expansion - The process TCC goes through when it scans a command line and substitutes the appropriate actual values for aliases, alias parameters, batch file parameters, user defined functions, and variables. See also Parsing.

Command Processor - A program which interprets commands entered interactively or stored in a file (referred to as a batch file in the environment discussed here), and executes other programs. Also called Command Interpreter.

Command Prompt - A prompt displayed on the screen by TCC when it is ready for another command to be entered and executed.

Command Recall - See Command History.

Command Separator - One or more characters used to separate multiple commands on the same command line. See Multiple Commands.

Command Tail - The contents of the command line after removing the command name. See Separating the command from its command tail

Compound Command - See Multiple Commands.

Compression - A feature which compresses data as it is stored in a disk file, and expands it as it is read back, resulting in more efficient use of disk space. This feature may be provided by hardware, software, or a combination of both. The software may, but need not, be part of the operating system. NTFS provides an attribute to indicate whether or not a file is compressed. Accessing compressed files requires slightly more processor time to perform the compression and expansion, but this is often compensated by the reduced data transfer time.

COMSPEC - An environment variable which defines where to find the character-mode command processor to start a secondary shell.

Condition - short for conditional expression.

Conditional Commands - A command processor feature allowing commands to be executed or skipped depending on the results of a previous command. See also: Exit Code.

Conditional Expression - See Conditional Expression.

Console - See Character Mode.

Console Mode - See Character Mode.

Control Character - A character which does not have a printable or displayable representation, but, when encountered in a stream of characters, performs a specific action. In ASCII the codes for these characters are in the range [0,31] or it is 127; each character also has a two- or three-character symbol for representing it in plain text. The common PC keyboard for U.S. use has special keys for some, i.e., ESC, CR, BS, HT, DEL. Each control character in ASCII can be generated by pressing the Ctrl key simultaneously with another key. For more information see ASCII, Key Codes & ANSI Commands.

Country Settings - The internal settings which tell the operating system how to interpret keyboard characters which vary from country to country, which character set to use, and how to retrieve and display date, time, and other information in the format appropriate to a particular country or region. See also Code Page.

CPU - See Central Processing Unit.

CR -  See Carriage Return

CRC - See Cyclic Redundancy Code.

Critical Error - An error, usually related to a physical or hardware problem with input, output, or network access, which prevents a program from continuing.

Current Directory - The directory in which all file operations of a selected drive will take place unless otherwise specified by an explicit path. The current directory is typically displayed as part of the command prompt. Also called the Current Working Directory.

Current Drive - The disk drive on which all file operations will take place unless otherwise specified. The current drive is typically displayed as part of the command prompt.

Current Working Directory - Alternate name for Current Directory.

Cursor - A movable marker on the screen to show where text will be entered when you type at the keyboard, or which object on the screen will be affected when a mouse button is clicked.

Cyclic Redundancy Code (CRC) - A sequence of characters, associated with a block of data, which provide a reasonably unique signature, used to detect the possibility of the data being corrupted in storage or transmission.