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                                  GLOSSARY                                
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Adapter:  A term used to refer to printed-circuit cards that plug into a 
     computer and controls a device, such as a display or a printer.

ANSI:     American National Standards Institute
     
Autoexec.bat:  The name reserved for a batch file containing commands that are 
     carried out by DOS each time the system is started. An AUTOEXEC.BAT file
     can be used to perform desired startup procedures without having to type
     the commands each time.

Application program:     A program, such as a word processor, that performs a 
     specific task.  The term usually refers to an application of the computer
     to a particular type of work.

Archive:  Perform duplication of  files on a separate disk or on a backup tape
     for safekeeping. The DOS Backup command helps archive files.  The DOS
     Restore command can, if necessary, be used to return archived files to the
     disk from which they were backed up.

ASCII:    A standardized coding scheme that uses numeric values to represent 
     letters, numbers, symbols, and so on. ASCII is an acronym for American
     Standard Code for Information Interchange and is widely used in coding
     information for computers.

ASCII transfer protocol: This protocol acts as if the sender is typing the 
     characters and the receiver is recording them. However, there is no error
     detection in this protocol.  You can use this protocol to upload a
     prepared message when connected to a BBS.

Asynchronous Data:  Data sent usually in parallel mode without a clock pulse. 
     Time intervals between transmitted bits may be of unequal lengths.

AT Command set:     A set of dialing commands used by the comouter to control 
     the modem.  These commands wew developed by Hayes Microcomputer Products
     and have become a standard in the modem industry.

AUX: Short for auxiliary. The communications port DOS uses unless instructed 
     otherwise. AUX can be either COM1 or COM2 in versions of DOS through 3.2;
     it can be COM1, COM2, COM3, or COM4 in version 3.3.

Back up:  To copy one or more files to diskettes or tapes for safekeeping.  See
     Archiving.


Backspace key: The key labeled with a single, left-pointing arrow.  It erases 
     characters you have typed.

BAK: The extension assigned by many word processors to the next-most-recent 
     version of a text file. If the working copy of a file is damaged, the BAK
     file can be used to salvage a near-current version of the document.

BASIC:    A programming language included with versions of DOS; BASIC is an 
     acronym for Beginner's All-purpose Symbolic Instruction Code.

Batch file:    A text file containing DOS commands whose extension is BAT. When
     you type the name of the batch file while DOS is at the command level, DOS
     carries out the commands contained in the file.

Batch Ymodem:  This protocol is a variation on Ymodem, which allows multiple 
     files to be sent per transfer. While transferring files, it keeps the
     correct name, size, and date, and may use 128 or 1024 byte block sizes.

Baud Rate:     Number of changes the modem's analog carrier signal goes through
     per second. Not to be confused with BPS. Named for Henri Baudot. Using
     muultiplexing, a signal may transfer more BPS than baudrate would indi-
     cate, for example, a [1200] or [2400] bps modem operates at 600 baud.


Baud:     The rate at which data is transmitted over a communications link. One
     character per second equals approximately 10 baud.

BiModem:  This protocol allows simultaneous bidirectional file transfers.

Binary:   The base-2 numbering system whose only digits are 0 and 1. The binary
     system is particularly well suited to use with computers because the two
     digits can be represented by the presence (1) or absence (0) of a voltage.

Bit: The smallest unit of information used with computers; corresponds to a 
     binary digit (either 0 or 1). Eight bits make up one byte.

Boot:     To start up a computer; derived from, "Pull yourself up by your own 
     bootstraps".  A cold boot is when the computer's power is cycled.  A warm
     boot is performed by pressing the [Ctrl][Alt][Del] keys together.

BPS: Bits per second. The data transfer rate of a serial interface (not to be 
     confused with BAUD). Below 600 bps, baud and bps are almost the same.

Byte:     The unit of measure used for computer memory and data storage. One 
     byte contains eight bits and can store one character (a letter, number, or
     punctuation mark, or other symbol).

Carrier:  A continuous frequency signal created by the modem that carries a 
     data signal between communicating computers over phone lines.  A "NO
     CARRIER" message means no connection.  

Character string:   A group of characters that you tell DOS to treat as a set 
     of letters or numbers, rather than as a command.

CIS Quick B:   This protocol is used only on the Compuserve Information Service
     (CIS). It is fast and specially suited for the networks used in accessing
     CIS, which have large turnaround delays. A CIS Quick B transfer, both
     sending and receiving, is totally controlled by Compuserve.

COBOL:    A programming lsnguage specifically designed for business applica
     tions.

Color/Graphics Adapter (CGA): A printed-circuit card in the computer that 
     controls the display. CGA shows both text and graphics at low resolution
     in up to sixteen colors.

Command file:  A file that contains the program or instructions required to 
     carry out a command. If the file's extension is COM or EXE, the command
     file contains machine instructions; if its extension is BAT, the command
     file is a batch file containing DOS commands in ASCII format.


Command:  An instruction you use to control a computer program, such as DOS or
     an application program.

Communications:     The transmission of data between computers; also called 
     telecommunications.

COMx:     Short for communications. The names of the computer's serial communi
     cations ports. All versions of DOS recognize COM1 and COM2; version 3.3
     also recognizes COM3 and COM4.

CON: Short for console. The name by which DOS refers to the keyboard (input) 
     and the display (output).

Control key:   The key labeled Ctrl which is used like the Shift key, i.e., by
     holding it down while pressing another key. The Control key usually causes
     something to happen rather than displaying a character on the screen. If
     displayed, it is shown as ^ , as in the end-of-file marker, ^ Z (Ctrl-Z). 
     The ^ symbol is called a caret.

CPU: An acronym for Central Processing Unit, it's the part of a computer that 
     performs calculations and processes information. In most microcomputers
     that use DOS the CPU is the 8086/8088, 80286, or 80386 chip.


Ctrl-Break:    The key combination to cancel a command.  Enter it by holding 
     down the Ctrl key and pressing the Break key. 

Ctrl-C:   Same as Ctrl-Break.

Ctrl-Num Lock: The key combination that stops DOS until you press any other 
     key. Usually used to freeze the display so you can view long displays. 
     Entered by holding down the Ctrl key and pressing the Num Lock key.

Ctrl-S:   Same as Ctrl-Num Lock.
     
Ctrl-Z:   The key combination that creates a special character used by DOS to 
     mark the end of a file. It's created by holding down the Ctrl key and
     pressing Z, or by pressing the function key labeled F6.

Ctrl-P:   Same as Ctrl-PrtSc.
     
Ctrl-PrtSc:    The key combination that controls simultaneous printing and 
     displaying. Press Ctrl-PrtSc once to cause DOS to print everything that is
     displayed on the screen.  Pressing Ctrl-PrtSc again causes DOS to stop
     printing. The command is entered by holding down the Ctrl key and pressing
     the PrtSc key.

Current directory:  The directory in which DOS looks for files unless otherwise
     instructed.

Current drive: The drive containing the disk on which DOS looks for a directory
     or file unless otherwise instructed.

Cyclic-Redundancy-Check (CRC):     Used to verify data block integrity.  In a 
     typical scheme, 2 CRC bytes are added to each user data block.  The 2
     bytes are computed from the user data, by digital logical chips.  The
     mathematical model is polynomials with binary coefficients.  When reading
     back data, the CRC bytes are read and compared to new CRC bytes computed
     from the read back block to detect a read error. The read back error check
     process is mathematically equivalent to dividing the read block, including
     its CRC, by a binomial polynomial. If the division remainder is zero, the
     data is error free.

Data file:     A file containing the information needed by a program.  The 
     information can be numbers, text, or a combination of the two.

Data:     The numbers and text processed by a computer while doing its work.
     
Data bit: A signal used in serial communications to represent the transmission
     of a character; seven or eight data bits can be used to represent one
     character.


Device name:   The name by which DOS refers to a device.  For example, DOS 
     refers to printers by, PRN, LPT1, LPT2, or LPT3.  Device names are treated
     like file names by DOS.

Device:   A piece of computer equipment that performs a specific task.  This 
     may be a monitor, printer, or disk drive.  The program that controls a
     device is called a device driver.

Directory:     The index of files that DOS maintains on a disk. The directory 
     entry for each file includes the file's name, extension, size, date and
     time it was created or last changed, and the location of the beginning of
     the file. The last item is not displayed by the Directory command.

Disk drive:    The device that rotates a disk in order to read (retrieve) and 
     write (store) information.

Disk :    A magnetically coated disk used to store information. The term is 
     used when no distinction need be made between a diskette and a fixed disk.

Diskette drive:     A disk drive used for writing data to and reading data from
     diskettes.


Diskette: A disk for storing files, made of thin plastic and enclosed in a 
     protective jacket.

Display:  The screen on which the computer shows both what you type at the 
     keyboard and the result of its work.  The screen is assumed by DOS to be
     the standard output device unless a different device is specified.

Drive letter:  The letter that identifies a disk drive.
     
Edit:     To change the contents of a file, usually with a word processor or an
     editing program such as Edlin.

Echo:     The appearance of characters (from your computer) on your screen. 
     Full Duplex means that the characters are remotely echoed from the
     receiving computer; Half Duplex means that the characters are echoed
     directly from your keyboard.

Editor:   A program used to create or change text files; also called a text 
     editor.

EDLIN:    The DOS text editor.
     


Enhanced Graphics Adapter (EGA):   A printed-circuit card in the computer that
     controls the display. EGA shows both text and graphics at medium resolu-
     tion in up to 64 colors.

Enter key:     The key you press to tell DOS that you have finished typing a 
     line.  The key is labeled "Return" on some keyboards.

Escape key:    The key labeled Esc that cancels a line you have typed but have
     not yet entered by pressing the Enter key.

Extension:     A suffix of up to three characters that can be added to a file 
     name to identify the contents of the file more precisely.

File name:     A name of up to eight characters that you assign and that DOS 
     uses to find a file on a disk.  The file name can be followed by a period
     and three additional characters called the file name extension.

File:     A named collection of information stored on a disk.  A file usually 
     contains either data or program instructions.

Filespec: The complete specification of a file.  The filespec can include a 
     drive letter, path name, file name, and an extension.


Filter command:     A DOS command that reads standard input, processes it in 
     some way and writes the result to standard output.

Fixed disk:    A disk of large capacity (10 MB or more) that cannot be removed
     from its drive. Also called a hard disk.

Floppy disk:   See diskette.
     
Format:   To prepare a disk for use.
     
Function key:  One of several keys, usually labeled F1, F2, and so on, that 
     cause DOS (or an application program) to perform a certain function, such
     as copying characters in a line of text.

Full Duplex:   Allowing data to move in either direction simultaneously.  Also
     known simply as DUPLEX.

Half Duplex:   Able to transmit data in either direction, but in only one 
     direction at a time. Half duplex is actually an implementation of SIMPLEX
     in both directions).

Hard disk:     See fixed disk.
     
Hardware: The equipment that makes up a computer system, as opposed to the 
     programs, or software.

Hexadecimal:   The base-16 numbering system whose digits are 0 through F (the 
     letters A through F represent the decimal numbers 10 through 15).  The hex
     numbering is often used in computer programming because it is easily
     converted to and from binary.  Binary is the base-2 numbering system the
     computer itself uses.

Hidden file:   A file, usually used only by DOS, that is not listed when you 
     display the directory with the DOS command (DIR). Hidden files cannot be
     erased, copied, or otherwise affected by DOS commands. 

Hierarchical filing system:   See multilevel filing system.
     
Initialize:    See format.
     
Input:    The data that a program reads.
     
Input/output:  A term that refers to the devices and processes involved in the
     computer's reading (input) and writing (output) data.

I/O: Abbreviation for input/output.
     
Keyboard: The device consisting of alphabetic and other keys where instructions
     and data are typed into the computer.  The keyboard is assumed by DOS to
     be the standard input device unless a different device is specified.

Integrated circuit: An electronic device that combines thousands of transistors
     on a small sliver, or chip, of silicon. Such devices are the building
     blocks of computers. Also referred to as a chip.

Interface:     The boundary between two systems or entities, such as a disk 
     drive and the computer, or the user and a program.

Jmodem:   This protocol is designed to maximize the amount of data that can be
     transferred in a given time. It sends very long blocks of data using 16
     bit CRC error correction and compressing the data wherever possible.

Kermit:   This protocol is designed to permit computers of different types to 
     send files to each other. Almost any computer using Kermit can be set up
     to send files to another computer using Kermit.


LPT1, LPT2, LPT3:   Short for line printer. The names that DOS uses to refer to
     the three ports to which parallel printers can be attached.
