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╔══════════════════════════════════════════════════════════════════════════╗ ║ GLOSSARY ║ ╚══════════════════════════════════════════════════════════════════════════╝ 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 computer 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 Archive. <GLOSSARY 1 20> 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. AKA: Floppy Disk. 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. <GLOSSARY 10 2> Format: To prepare a disk for use. AKA: Initialize. 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. <GLOSSARY 12 5> 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. <GLOSSARY 16 16> Initialize: See format. <GLOSSARY 12 10> 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. MegaLink: The goal of this protocol is to design and implement a protocol that is fast, reliable and inexpensive. Megalink is a full streaming protocol. It uses a block of 512 bytes and a CRC-32 error correction to improve the performance. Microcomputer: A small computer system, usually used by only one person. Microprocessor: An integrated circuit, or chip, that contains the circuits the computer needs to calculate and to communicate with the other parts of the system. MNP: (Microcom Networking Protocol). A hardware-based modem error checking method. MNP converts asynchronous data to a synchronous bit stream, allowing the two framing bits normally required for each async character to be dispensed with. Modem: A device that permits the transmission of computer data over tele phone lines. Contraction of modulator-demodulator. Modem7: Modem7 is a relative of Xmodem. It passes the filename before starting the transfer. It is common on CP/M systems. This protocol allows more than one file to be sent at a time. Monitor: A device that displays computer input and output; usually used synonymously with display. Monochrome Display Adapter (MDA): A printed-circuit card in the system unit of a computer that controls the display. Shows text only at medium resolution in one color. Monochrome: A term used to describe a computer display capable of displaying one color (usually white, green, or amber). Multicolor Graphics Array (MCGA): A printed-circuit card in a computer that controls the display. MCGA shows both text and graphics at low to medium resolution in up to 256 colors, and is used in IBM PS/2 model computers. Multilevel filing system: A computer filing system that lets you define directories within other directories, creating a structure with many levels. Also called a tree-structured or hierarchical filing system. Network: A group of computers that share resources, such as disk drives and printers. The computers are linked together by printed-circuit cards, cables, and network software. Null Modem: A cable used to connect the serial ports of two computers in such a fashion that each thinks it is "talking" to a modem. Very fast serial data transfer may be acheived with a null modem. Parity: A computer data checking method using an extra bit in which the total number of binary 1's (or 0's) in a byte is always odd or always even; thus, in an odd parity scheme, every byte has eight bits of data and one parity bit. If using odd parity and the number of 1 bits comprising the byte of data is not odd, the 9th or parity bit is set to 1 to create the odd parity. In this way, a byte of data can be checked for accurate transmission by simply counting the bits for an odd parity indication. If the count is ever even, an error is indicated. Operating system: A program that coordinates the operation of all parts of a computer system. Output: The result of a program's processing its input data. Parallel communications: A communications technique that uses multiple inter connecting wires to send eight bits of a byte at once (in parallel). Parallel port: The port to which the printer is usually attached. Parameter: A qualifier that you include with a command to define more specifically what you want DOS to do; also called an argument or an op- tion. Parity: An error-detection technique used for accuracy in data communica tion s. Path name: The portion of a file specification that defines the path to the file; can include a drive letter followed by a colon. Path: The list of directory names that defines the location of a directory to DOS. The path statement goes into the AUTOEXEC.BAT file and follows the form: PATH=C:\;C:\DOS;C:\BAT;C:\WP;C:\DB;C:\UTIL Pipe: To direct the output of one command to be used as the input of another command. The pipe symbol DOS uses is the broken vertical bar (|). Port: The electrical connection through which the computer sends and receives data to and from devices or other computers. Print queue: The list of files to be printed by DOS; you create, examine, and modify the print queue with the Print command. AKA: Queue. Printed-circuit card: A thin, rectangular card or board, usually made of fiberglass or epoxy and coated with copper. A circuit is etched into the copper, and electronic devices, such as integrated circuits, are soldered to the circuit. Computer systems are made up of these cards. Printer: A device that produces images of text and graphics on paper. PRN: Short for printer. The printer DOS uses unless instructed otherwise. Can refer to LPT1, LPT2, or LPT3. Program: A set of instructions for a computer. Prompt: A request displayed by the computer for you to provide some information or perform an action. One of the most useful things that can be done is put the command: prompt $p$g into the AUTOEXEC.BAT file. This will tell the ANSI system to make the prompt indicate the name of the directory the drive is in. Example: C:\DOS> or C:DOS\UTL> Protocol: A set of conventions governing the format of messages to be exchanged within a communications system. Puma: This protocol has a full color display of transfer status. It can transfer up to 99 files in a single batch using dynamic block scaling for optimal data throughput. Like Zmodem, the resume option can continue an interrupted transfer. Queue: See Print Queue. <GLOSSARY 18 21> RAM disk: See virtual disk. <GLOSSARY 26 21> Read-only file: A file whose read-only attribute is set so that its contents can be displayed and read, but not changed. RAM: Short for Random Access Memory. The memory that DOS uses for programs and data; RAM content changes often while you use the computer, and is lost when the computer is turned off. Redirection: The process of causing a command or program to take its input from a file or device other than the keyboard (standard input), or of causing the output of a command or program to be sent to a file or device other than the display (standard output). The DOS redirection symbols are the greater-than (>) and less-than (<) signs. Relaxed Xmodem: This is the same as Xmodem except that it has a longer delay time. This is for use with remote services that can not tolerate strict timing during Xmodem transfers. Replaceable parameter: A symbolic reference, consisting of a percent sign followed by a one-digit number (such as %1), that can be included with commands in a batch file to refer to the parameters entered with the batch command. Return key: The Enter key. ROM: Short for Read-Only Memory, the type of computer memory that is permanent ly recorded in hardware. ROM contains instructions that help a computer carry out routine tasks, such as starting itself up. The contents of ROM cannot be changed and are not lost (non-volatile) when the computer is turned off. Root directory: The main directory that DOS creates on each disk; the top directory in a multilevel filing system. RS-232 or RS-232C: The standard computer hardware interface used for computer asynchronous communications connections. SEAlink: SEAlink is a advanced version of Xmodem developed by System Enhance ment Associates. It is a sliding window protocol. SEAlink passes a name, size, and date of the transferring file and allows multiple files to be transfered. Serial communications: A communications technique that uses as few as two interconnecting wires to transmit bits one after the other. Serial port: The communications port (COM1, COM2, COM3, or COM4) to which devices, such as a modem or a serial printer, can be attached. Serial: A serial interface sends a stream of data bits separated by time or an electrical signal. For communications, serial interfaces often use a PROTOCOL, dividing the data stream into packets which may be checksummed to verify accuracy. Shareware: Software marketing system where the user gets to use the program for a period of time (usually 30 days) before they are expected to purchase (register) the program. Shareware is most often less expensive than retail software and is often times just as good or even better. Simplex: Simplex transmission allows data to flow in one direction only (ex., most parallel printer interfaces or the monitor). Software: The programs that are used with a computer system. Standard input: The device from which a program reads its input unless the input is redirected. In normal DOS operation, standard input is the keyboard. Standard output: The device to which a program sends its output unless the output is redirected. In normal DOS operation, standard output is the display. Start/stop bits: In serial, asynchronous transmission, start/stop bits indicate the beginning and end of each 7- or 8-bit data character. Stop bit: A signal used in serial communications that marks the end of a character. Sructured Query Language (SQL): A query language developed by IBM that allows you to access your database. This language can be used with a variety of database management products and can access databases on mainframes, minis, and PCs. STY: A pseudo-teletype, which is a two-way pipeline with a job on one end and a fake keyboard-TTY on the other. Also, a standard program which provides a pipeline from its controlling TTY to a pseudo-teletype (and thence to another TTY, thereby providing a "sub-TTY"). Subdirectory: A directory that is attached to a higher level directory. For example, in the path statement: C:\DOS\UTL, the subdirectory, UTL is attached to the directory DOS. Synchronous Data Transmission: Data sent, usually in serial mode, with a clock pulse. No stop and start bits are needed. System prompt: The characters DOS displays when it is at the command level (ready to accept a command); unless you specify otherwise, the system prompt consists of the letter of the current drive followed by a greater-than sign (for example, A>). System program: A program whose purpose is to control the operation of all or part of the computer system, such as managing the printer or interpret- ing commands. Telecommunications: See communications. <GLOSSARY 6 5> Temporary file: A file that DOS may create when told to redirect command input or output; deleted by DOS when the command is completed. Telink: This protocol is primarily found on Fido BBS systems. It is basically the Xmodem protocol using CRC checking with an extra block sent ahead of the file telling its name, size, and date. This protocol allows more than one file to be sent at a time. Text editor : A program that you use to create or change text files. Also called simply an editor. The one supplied with the DOS system is named EDLIN. Text file: A file that you can read (contains ordinary letters, numbers, and punctuation marks). Text: Ordinary, readable characters, including the uppercase and lowercase letters of the alphabet, the numerals 0 through 9, and punctuation marks. TSR: Terminate and Stay Ready program. Also called memory resident or pop-up program. A software program that stays in memory while you run other pro- grams. To get the TSR to pop up on your screen, you simply press a designated "hotkey" combination. TTY: Terminal of the teletype variety, characterized by a noisy mechanical printer, a very limited character set, and poor print quality. Usage: antiquated (like the TTY's themselves). Sometimes used to refer to any terminal at all; sometimes used to refer to the particular terminal controlling a job. Update: To change a file, creating a new (or updated) version. Video Graphics Array (VGA): A printed-circuit card in the computer that controls the display. VGA shows both text and graphics at medium to high resolution in up to 256 colors; used in IBM PS/2 model computers. V.32: A CCITT specification defining a family of FULL DUPLEX modems using 5 digital bits for each carrier change at a 2400 baud rate. While this produces a raw throughput of 12,000 bps, 1 out of 5 bits is used for error correction, reducing throughput to 9,600 bps. Virtual disk: A portion of the computer's Random Access Memory reserved for use as a simulated disk drive. Also called an electronic or RAM disk. Unless saved on a physical disk, the contents of a virtual disk are lost (volatile) when the computer is turned off. Volume label: An 11-character identifying name you can assign to a disk. Wildcard character: A special character that, like the wild card in a card game, can be used to represent any other character. DOS recognizes two wildcard characters: the question mark (?), which can represent any single character, and the asterisk (*), which can represent more than one character. Write-protect: To cover the small notch or opening on a diskette so that new or changed information cannot be written onto the diskette. WYSIWYG: What you see is what you get (pronounced "wiz-ee-wig"). A desktop publishing phrease referring to the match between interfaces and printers. It means that what you see on the computer screen is what you'll get on the printed copy. X.25: A CCITT standard that describes how data is handled in a packet switched network. Xmodem-1K: This is a variation of Xmodem which uses blocks that may be 128 bytes or 1024 bytes in size. Most communications packages support this protocol by allow 1K block in Xmodem protocol. Some BBS softwares refer to Xmodem-1K as Ymodem. Ymodem sends the name, size and date of the file but Xmodem-1K does not. If the filename 'UNKNOWN.$$$' shows in the transfer window during a Ymodem transfer, it is likely that the BBS software is using Xmodem-1K, in this case, you should select Xmodem protocol. Xmodem: A protocol for transferring blocks of data via modem with a high degree of accuracy. Developed by Ward Christensen for CP/M systems in the late '70s and now the basic standard for error-detected data transfer. Xmodem is the most popular protocol in use today, but it is slowly being replaced by quicker and more reliable protocols. Error checking is a checksum or a the Cyclic Redundancy Check. The Xmodem protocol requires a setup of no parity, 8 data bits, and 1 stop bit. While sending a file, Xmodem always uses a 128 byte block. XON/XOFF: Protocol for controlling the flow of data. If you dial into a timesharing system in which many users simultaneously use the same comput- er and if the system is about to overflow, it will send an XOFF character to your computer. The XON character will be sent to you when the system is ready to receive again. Ymodem-G: This protocol is a variation on Batch Ymodem. It achieves very high transfer rates by sending blocks one after another without waiting for acknowledgement. This however means that an error-free link such as an error-correcting modem or null modem cable between two computers is needed. If an error is detected by the receiver, the transfer is aborted. It allows transferring multiple files. Ymodem: This is a variation of the Xmodem which uses blocks that may be 128 bytes or 1024 bytes in size and keeps the correct name, size, and date. Zmodem: This advanced protocol is both fast and reliable, and offers many features. Zmodem can transfer a group of files in one batch, while keeping the exact file size and dates. Zmodem detects and recovers from errors quickly. The Zmodem Recovery feature can resume an interrupted transfer. The Zmodem protocol is a feature built into the Telix communication program.