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- Newsgroups: comp.sys.amiga.datacomm
- Path: sparky!uunet!ftpbox!mothost!white!rtsg.mot.com!king
- From: king@rtsg.mot.com (Steven King, Software Archaeologist)
- Subject: Re: Question about terminology
- Message-ID: <1992Sep3.140836.23812@rtsg.mot.com>
- Sender: news@rtsg.mot.com
- Nntp-Posting-Host: orchid3
- Reply-To: king@rtsg.mot.com
- Organization: Motorola Inc., Cellular Infrastructure Group
- References: <92246.102655PROHVK38@TREARN.BITNET>
- Date: Thu, 3 Sep 1992 14:08:36 GMT
- Lines: 52
-
- Cem Turgay <PROHVK38@TREARN.BITNET> publicly declared:
- >Hi, Could I learn the meaning of V32, V42 and bis abbreviations?
-
- No, absolutely not! If we told just ANYONE the secrets, we wouldn't be
- known as the gurus anymore.
-
- Oh, well, all right. Consider it "Guru Largesse"... :-) This is a
- summary I put together based on the "What You Need To Know About
- Modems" guide written by Patrick Chen. The entire guide is longer than
- I'm willing to post (2200 lines, about 100K) but I'll mail it to anyone
- who sends me email asking for it. No, I can't put it up for ftp since
- I don't have ftp access.
-
-
- MODEM Quick Info
- ----------------
- CCITT V.22 1200 bps Modulation protocol
- CCITT V.22bis 2400 bps Modulation protocol
- CCITT V.32 9600 bps Modulation protocol (1984, also 4800 bps)
- CCITT V.32bis 14400 bps Modulation protocol (1991, includes V.32)
- CCITT V.42 Error Correction protocol
- CCITT V.42bis Data Compression protocol (4:1, used with V.42)
- MNP-4 Error Correction protocol
- MNP-5 Data Compression protocol (2:1, used with MNP-4)
-
- Notes
- -----
- V.42 and MNP-4 may also increase thru-put by approx 15% due to
- stripping start & stop bits from data.
-
- V.42bis and MNP-5 may not speed up transfer of compressed files.
- MNP-5 may actually slow down transfer of a compressed file.
-
- Dual Standard: U.S. Robotics, Telebit, Hayes, CompuCom etc, make modems
- that support V.32 and their own proprietary protocols for 9600 bps.
-
- A modem that supports only a proprietary protocol for 9600 bps can
- transfer data at 9600 bps only to another modem that supports the same
- propietary protocol (example: an HST modem only to another HST modem).
-
- Any brand V.32 modem can transfer data at 9600 bps to any brand V.32 modem.
-
- Any V.32bis modem can transfer data at 14400 bps to any other V.32bis modem.
-
- A V.32bis modem can fall back from 14400 bps to 12000/9600/7200/4800 bps.
-
-
- --
- -------------------------------------------------------+-----------------------
- A CPU cycle is a terrible thing to waste. | Steven King
- | Motorola Cellular
- | king@rtsg.mot.com
-