Telecommunications Glossary

compiled by Gaelyne R. Moranec

Reprinted from Commodore World Issue #4

103: Officially, 'Bell 103' which is the standard controlling transmission at 300 bps in the United States.
212A: Officially, 'Bell 212A' which is the standard controlling transmission at 1200 bps in the United States.
alias: A name that users can use on a bulletin board that is not their own. [Also called handle].
ANSI emulation: The ability to send, receive, and display ANSI graphics.
ANSI graphics: A set of cursor control codes which originated on the VT100 smart terminal.
answer mode: When a modem is ready to pick up the phone when it rings. After picking up the phone, the modem will attempt to make a connection with another modem. All BBS's are in answer mode.
ASCII: An acronym for American Standard Code of Information Interchange. MS-DOS style computers use this, while Commodore computers use PETASCII. Most CBM terminal programs can translate text files between the two formats.
auto-answer: When a modem has the ability to automatically pick up the phone when the phone rings and then attempt to connect with another computer.
auto-baud detect: The ability of a modem to change to a lower bps rate if the computer it is calling is unable to communicate at the requested speed.
auto-download: The feature of some protocols where the BBS can automatically make your communications program start a download or upload. Novaterm's Z-Modem download has this ability.
auto-reliable: The ability of a modem to be able to communicate both with modems that do have error-control and/or data compression, and those that do not.
batch file transfer: This is when more than one file is sent at a time by a file transfer protocol.
baud: A term referring to the speed at which modems communicate. Technically, it is the number of changes in an electronic signal per second. Since the number of changes used to be the same as the number of bits sent or received per second, bps and baud are often used interchangeably.
BBS: An acronym for Bulletin Board System. Usually it is a home computer that has a modem attached and is waiting for calls from other computers. BBS can also be expanded more simply to 'bulletin board' or 'board'.
block: A group of data bytes. For example, when downloading a program, block sizes of 128 or 1024 characters are common.
block size: This term, when used with either error control or data compression protocols, refers to the number of characters to be sent at one time. If error control is used, the codes are sent immediately following this block.
bps: Bits Per Second. The transmission speed of most modems is measured in baud or bps. Bps is literally the number of bits sent by the modem every second.
buffer: To save all incoming data in memory. Most term programs have buffers. Usually what is saved to buffer is then manually saved to disk by the user.
bulletin: A special message posted on a BBS, usually written by the SysOp.
capture: To 'catch' text that is being sent to your computer from a BBS and put it in a buffer or a file.
capture buffer: The area in a computer's memory where a communications program stores incoming data that is to be saved.
carrier: The tone that the modem sends over the phone lines. Data is modulated onto this tone, so it is referred to as the carrier tone.
carrier detect: when the modem senses a carrier, you are connected to a BBS or online service. [Abbreviated as CD].
characters per second: The number of bytes or characters sent over the phone lines in 1 second. [Abbreviated as CPS].
chat mode: A terminal program mode used to "chat" with someone on the other end of the line. Only after the return key is hit will the line of text be sent to the modem.
checksum: Commonly used when downloading a program, and in error control protocols. The checksum is the result of a mathematical equation.
Co-SysOp: Person who assists the Sysop of a BBS and has a little more access than regular users.
conference: A group of related messages on a BBS. Often, many BBS's are linked together for a conference so that users on all the BBS's can see and reply to the messages.
connect speed: The speed, generally stated in bits per second, which your modem uses when it connects with another.
connection: The actual contact with another computer.
control character: Any of the 32 ASCII characters that do not print on your screen or printer. These characters are usually used to control your computer.
CRC: Stands for Cyclic Redundancy Check. CRC is a system to make sure that a block of data is as free from error as possible.
CTS: Clear To Send. This is when the modem lets the other computer know that it can send information to the other computer.
CTS/RTS: The method of flow control that uses the CTS and RTS signals on an RS-232 connection. This is a form of hardware handshaking, enabling connected systems to determine when data can be transferred.
data bits: [1] The number of bits that the modem uses to represent one byte. This is usually 8, though it can be 7, since ASCII text characters need only 7 of the 8 bits. [2] The actual data bits within a byte being sent through the phone lines.
data compression: Using data compression, a modem can send information faster. Both sending and receiving modems must have this ability to use it. It does not compress files which are already compressed, however.
data modem: A modem that does not have the ability to send or receive fax transmissions.
DB-25: The 25 pin plug that connects an RS-232C cable to the RS-232 port. Modems generally use this connector.
DB-9: The 9 pin plug that connects an RS-232C cable to the RS-232 port.
DCD: Data Carrier Detect. This tells the computer whether or not the modem is connected to another modem.
DCE: Data Communications Equipment. These are computer peripherals that communicate. A modem is a DCE.
dialout facility: A service which you dial a local number which connects you to other computer systems. Telenet is an example.
disconnect: To hang up the phone and cause the connection between your modem and another computer to be stopped.
door: An external program of the BBS. Usually either games or offline mail facilities are doors.
download: To receive a computer file from a bulletin board.
DSR: Data Set Ready. This indicates that the modem is on, and ready to accept input from the computer.
DTE: Data Terminal Equipment. This is computer equipment which is not directly responsible for communicating, for example, the computer itself and printers.
DTR: Data Terminal Ready. The DTR signal is sent from the computer to the modem, to let the modem know that the computer is ready to communicate.
E-mail: Electronic mail. Messages that are sent to individual people. Through networks, it is possible to send mail to anyone on any BBS in the network.
E-mail address: Similar to a postal mailing address, an address lets people know how you can be reached on a network. It may consist of numbers and/or words.
echo: A reference to an echomail conference. For example, "This echo has too many messages." Also used to decribe when a bulletin board or your terminal program sends back the characters that you type.
echomail: Many BBS's have message bases that are shared with other BBS's. Sometimes echomail can extend across the world.
effective transfer rate: This is the rate at which data can be sent after data compression has been accounted for.
error control: The ability of a modem to notice errors in trans-mission, and have any incorrect data re-sent.
escape sequence: A sequence of characters (usually +++) that tell the modem to change from data mode to command mode.
factory configuration: The way that your modem was set up when it left the factory. Typing AT? normally returns your modem to this setting.
fall-back: The ability of a modem to change to a lower speed when there is a problem communicating at the higher speed.
fall-forward: This is when a modem will change to a faster speed if line conditions improve after a fall-back occurs.
faxmodem: A modem that can send and receive faxes.
feature negotiation: Part of hand-shaking, where a modem determines the best speed, error control, and data compression protocols for connecting to another modem.
feed: Connection between a BBS and a message network.
feedback: A message that is sent by a user to the SysOp of a bulletin board.
FidoNet: A public network connecting thousands of BBS's around the world.
flow control: A method of controlling when information is or is not sent.
freq: Short for "File REQuest." It is used to get program(s) from a BBS, without logging on. Only Sysops can FREQ files from other Sysops. Users generally ask the Sysop to FREQ file(s) for them.
FTP: File Transfer Protocol. This is the method of transfering files on internet.
full duplex: The ability to simultaneously transmit and receive data.
half duplex: Mode which allows only one modem at a time to transmit information.
hand-shaking: General term for the methods two communications devices use to synchronize with each other.
Hayes AT command set: This is the set of commands used to operate Hayes and Hayes-compatible modems.
Hayes-compatible: Modem which supports the Hayes AT command set.
initialization string: A series of commands sent by your terminal program to configure your modem, usually when the program is started or when auto-dialing pre-defined communications service telephone numbers.
internet: This is the largest network of linked computers. Originally started by the U.S. Government.
internet address: This is an address used to reach someone on the internet.
internet relay chat: On the internet, 2 or more users to talk (type) to each other in "semi-real time". Messages may take a while to reach each other, but quick enough that they can wait for replys and "chat." [Same as IRC].
Kermit protocol: An almost error-free file transfer protocol usually used for text transfers.
LAPM: Link Access Procedure for Modems. A type of error control used by some modems. It is NOT a compression method, though some modem manufacturers have incorrectly advertised it as such.
line noise: This is interference on the telephone lines. It causes garbage to appear on your screen.
local echo: This is when a communications program will send information (either that you type or from a file) to your screen, as well as to the other modem.
logoff: To leave a BBS, and disconnect the phone line. [Same as exit, quit, goodbye].
logon: The process of connecting to a BBS. "Logon" can include the process of entering your name and password.
mailer: A program used by BBS's that allows other BBS's to call, so that mail and/or files can be transfered automatically between the two.
message base: A group of messages on a BBS pertaining to a certain topic..
MNP: Microcom Networking Protocol. A type of error control and data compression, created by Microcom, that many newer modems use. It is built into the modem, unlike software error correction in file transfer protocols. There are different MNP levels. Levels 1-4 are error control protocols, and level 5 is a data compression protocol that can compress data to about 50% of its original size. A modem with MNP-5 also has MNP-4. MNP 1-4 is also included in the CCITT V.42 error correction system.
modem: MODulator/DEModulator. The device used for computers to communicate over telephone lines.
moderator: The person who is in charge of a conference. This person usually has the task of making sure that users of the conference follow the conference rules.
netmail: Messages that are sent over networks of BBS's to specific people. Similar to Internet E-mail.
network: A group of BBS's that are "linked" together. This means that the BBS's share messages and sometimes files.
non-volatile memory: This is memory that many modems have which is not destroyed when the power is turned off.
null modem: A connection between two computers locally, causing the computers to act as if connected via a modem. Generally used to transfer data from one machine to another.
off-line: When your computer is not connected to another BBS.
off-line mail reader: A program that allows you to read messages and reply to them after you call a BBS.
on-line: When your computer is connected to a BBS.
on-line conference: This is when a group of people "get together" and have a conference using their computers. Major on-line services have this feature. [also called "real-time conference"].
on-line games: Any game that is played on a BBS.
on-line service: usually means a pay service such as Compuserve or GEnie.
packer: A BBS program which packs new messages together to be sent out by a mailer or download by a user for offline mail reading.
padding: This happens when a file that is being transferred ends in the middle of a block of data. The communications program must add blank data to fill up the block. Some term programs will "strip" this before saving the file to disk.
password: A special code that only you know which the BBS asks for each time you logon. Passwords should be changed frequently and should be something you can remember but that others won't guess.
post: To save a message that you have written on a BBS so that other people can see it.
protocol: A method of sending and receiving a program. There are many methods available, each with different advantages and disadvantages. Also used to describe the way that hardware error control is managed.
QWK: A type of mail packet.
RD: Receive Data. This is the wire in an RS-232C cable that receives data.
RJ-11: This is a normal phone jack. Modems usually have 2 jacks like this, one to connect to the phone line, and the other to connect to a telephone to use when the modem isn't in use.
RS-232 Interface: device which allows Commodore 64 and 128 computers to use common external modems designed for other platforms.
RS-232C: The name of a standard (created by the Electronics Industry Association) for communication between a computer and a serial device.
RTS: Request To Send. The computer tells the modem it wants to send information to the other computer. Only used in half duplex mode.
script language: Many term programs allow the user to write a program, or script, which allows them to use the program without actually typing anything.
SIG: Special Interest Group. This is similar to a message base, but it may also contain files.
Sysop: Short for SYStems OPerator. Person who is in charge of a BBS. Usually the person who paid for the BBS equipment and pays for the phone line.
tagline: Offline mail readers allow you to havea "tagline" at the end of your messages. This is often a funny saying or a quote.
terminal emulation: When a term program imitates a certain brand of terminal, such as ANSI, VT100, etc.
terminal program: A program that controls a modem, and has features that allow the user to do such things as upload, down-load, etc. Also called communications program or term program.
thread: A group of related messages on a BBS, within the same message base.
transfer: To send a computer program from one computer to another. "xfer" is an abbreviated way to say the same thing.
upload: To send a program from your computer to a BBS.
V.17: The CCITT standard for fax transmission at 14,400bps.
V.21: The international standard, controls transmission at 300bps.
V.22: The international standard for transmission at 1200bps.
V.22bis: The international standard, controls data transmission at 2400bps.
V.23: The CCITT protocol for transmission of 1200bps one way, 75bps the other way.
V.24: This, combined with V.28 is the CCITT standard equivalent to EIA's RS-232C standard.
V.28: Part of V.24.
V.29: The CCITT standard for 9600bps half-duplex communications.
V.32: The international standard controlling transmission at 9600bps.
V.32bis: The international standard for 14,400 bps modems.
V.42: A standard error control system that includes LAPM, as well as MNP 2-4.
V.42 compatible: Modem that follows all the V.42 specifications, except for LAPM error control (uses MNP instead).
V.42 compliant: Modem which follows all the V.42 specifications, and uses LAPM error control or MNP error control.
V.42bis: A CCITT standard for data compression. It can compress data with about a 3:1 compression ratio, 4:1 under the right conditions. Any modem with V.42bis also has V.42 error control.
V.Fast: The proposed CCITT standard for communications at up to 28,800bps.
Xmodem: A file transfer protocol developed by Ward Christensen. Slow by today's standards, but almost every communications program offers this protocol. [Same as Christensen protocol].
Xmodem-1K: Similar to Xmodem/CRC, but uses blocks of 1024 bytes, rather than 128. Faster than Xmodem, since it makes fewer error checks.
Xmodem/CRC: The same as Xmodem, but more reliable as it catches more errors.
Xoff: The CTRL-S character. This is often used to pause information that is being sent. The information will be continued when an CTRL-Q is received.
Xon: The CTRL-Q character. Continues paused information.
Xon/Xoff: The flow control method using the Xon and Xoff characters. This is a form of software handshaking, used to determine when data can be sent and/or recieved.
Ymodem: Protocol which transfers more than one file at a time. It can use both 1024 byte blocks and 128 byte blocks.
Ymodem-g: Ymodem, but changed to provide best results with error-correcting modems. Not widely available for Commodore terminal programs, although included in at least one CBM 128 BBS package.
Zmodem: Protocol known for its speed, auto-download, and batch download features.