johnboyd@OCDIS01.AF.MIL (John Boyd;) (09/10/90)
Realizing that one generally desires to operate at the highest reliable
speed possible, and that ever higher speed standards are coming into being;
I have the following questions:
1. Are V.42 and V.42bis different standards, or is one a shorthand
referral to the other?
2. How much of a consideration should the availability of the
above capabilities should the above be in a modem purchase
which one might make in the immediate (now-18months) future?
3. Since I occasionally communicate with PC-based BBSs, and will
potentially do a lot of traffic with Internet, is V.42[bis] a
single answer to two questions?
4. Are there any issues/questions I have not considered in the
above?
All input appreciated.
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johnboyd@ocdis01.af.mil 72341.1707@compuserve.com
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"Remember, just because you're paranoid doesn't necessarily mean there's
not someone out to get you" -Gallagher
-The opinions expressed here are my own. Did I REALLY say that?jjj@batgirl.hut.fi (Joni Jaakko J{rvenkyl{) (09/14/90)
In article <9009111424.AA26660@ocdis01.af.mil> johnboyd@OCDIS01.AF.MIL (John Boyd;) writes: > 1. Are V.42 and V.42bis different standards, or is one a shorthand > referral to the other? CCITT V.42 is a error correcting standard. CCITT V.42bis is a compression technique to be ran on the top of V.42. Together they give you error correction and data compression. Data compression affects mostly on text; MNP 5 has the compress ratio of 2:1 and V.42bis can make it up to 3:1. Needless to say, V.42bis won't give you greater throughput with compressed files (.ZIP, .Z etc), but it has the ability to turn itself off if compression is impossible - a feature which MNP 5 lacks. > 2. How much of a consideration should the availability of the > above capabilities should the above be in a modem purchase > which one might make in the immediate (now-18months) future? Very important, as CCITT V.42 and V.42bis are to be WORLDWIDE STANDARDS, compared to MNP which can licensed from Microcom only. Also all the biggest and most realiable modem manufacturers can already supply V.42 and V.42bis. V.42 also includes compatibility with MNP 4 error correction, so you got still error correction compatibility to modems using MNP. > 3. Since I occasionally communicate with PC-based BBSs, and will > potentially do a lot of traffic with Internet, is V.42[bis] a > single answer to two questions? (Look above) CCITT V.42bis - yes, but I would not consider bare V.42. -- jjj@niksula.hut.fi jjj@otax.tky.hut.fi fire me, fire until you die