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Async. modem glossary

Async. modem glossary. CCITT InternationalTelegraph and Telephone Consultative Commitee (now ITU-T ) ITU-T International Telecommuncations Union, Telecommunication Standardization Sector (former CCITT ) V. nn ITU-T (CCITT) recommended standards. modulation standards

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Async. modem glossary

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  1. Async. modem glossary CCITT InternationalTelegraph and Telephone Consultative Commitee (now ITU-T) ITU-T International Telecommuncations Union, Telecommunication Standardization Sector (former CCITT) V.nnITU-T (CCITT) recommended standards • modulation standards • Bell 103, V.21 110, 150, 300 bps • Bell 212A, V.22 1200 bps • V.22bis 2400 bps • V.32 2400, 4800, 9600 bps • V.32bis 7200, 9600, 12000, 14400 bps • V.Fast preliminary V.34 • V.34 28800, ..., 14400 bps • V.34bis 33600, ..., 14400 bps • V.90 56.700 bps • modulation fallback • V.90 --> V.34 --> V.32bis --> V.32 --> V.22bis --> V.22

  2. Async. modem glossary • speed buffering • interface speed • connection speed • flow control • RTS/CTS hardware control by special wires • XON/XOFF software control through special characters (Ctrl-Q/Ctrl-S) • ASL Automatic Speed Leveling during retraining • error control • MNP 1, 2, 3, 4 Microcom Networking Protocol • (de facto standard) • V.42 Link Access Protocol for Modems (LAPM) • error-control fallback • V.42 --> MNP4 --> MNP3 --> MNP2 --> MNP1 --> none

  3. Async. modem glossary • data compression • MNP3, 4 protocol optimization (108-120%) • MNP5, V42bis true compression, (up to 400%, depends on data) • compression fallback • V.42bis --> MNP5 --> none • DTE Data Terminal Equipment (computer) • DCE Data Communication Equipment (modem) • DTE-DCE signalling • DTR Data Terminal Ready, set by DTE • DSR Data Set Ready, set by modem • RTS, CTS Reday To Send, Clear To Send, used to hanshake on sped buffering • CD Carrier Detect, set by modem when communication to remote modem is established

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