3Com 56K manual Glossary

GLOSSARY 3

copies of transmitted frames until they are positively acknowledged by the receiving modem.

byte A group of binary digits stored and operated upon as a unit. A byte may have a coded value equal to a character in the ASCII code (letters, numbers), or have some other value meaningful to the computer. In user documentation, the term usually refers to 8-bit units or characters. 1 kilobyte (K) is equal to 1,024 bytes or characters; 64K indicates 65,536 bytes or characters.

call indicate A call originating tone defined by ITU-T recommendation V.8.

carrier A continuous frequency capable of being either modulated or impressed with another information carrying signal. Carriers are generated and maintained by modems via the transmission lines of the telephone companies.

CCITT Formerly, an international organization that defined standards for telegraphic and telephone equipment. It has been incorporated into its parent organization, International Telecommunication Union (ITU). Telecommunication standards are now covered under Telecommunications Standards Sector (TSS). ITU-T replaces CCITT. For example, the Bell 212A standard for 1200 bps communication in North America was referred to as CCITT V.22. It is now referred to as ITU-T V.22.

central office (CO) The facility to which devices, such as telephones, fax machines, and modems within a specific geographic area of a public telephone network are connected.

central office switch A device, located at the telephone company's central office, to which devices, such as telephones, fax machines, and modems are connected.

character A representation, coded in binary digits, of a letter, number, or other symbol.

characters per second A data transfer rate generally estimated from the bit rate and the (cps) character length.

For example, at 2400 bps, 8-bit characters with start and stop bits (for a total of ten bits per character) will be transmitted at a rate of approximately 240 characters per second (cps). Some protocols, such as HST and MNP, employ advanced techniques such as longer transmission frames and data compression to increase cps.