Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!ames!killer!vector!nobody From: desnoyer@Apple.COM (Peter Desnoyers) Newsgroups: comp.dcom.telecom Subject: Re: Query about Telebit Message-ID: Date: 30 Jan 89 19:31:09 GMT Sender: chip@vector.UUCP Lines: 32 Approved: telecom-request@vector.uucp X-Submissions-To: telecom@bu-cs.bu.edu X-Administrivia-To: telecom-request@vector.uucp X-TELECOM-Digest: volume 9, issue 39, message 1 In article david%ms.uky.edu@E.MS.UKY.EDU (David Herron -- One of the vertebrae) writes: >In article boottrax@csd4.milw.wisc.edu (Perry Victor Lea) writes: > >> Do not use a Telebit modem on an amiga, that is if it's over 9600 baud. >>Amiga systems use as a standard US Robotics ONLY! I have never found a 9600 + >>baud system that operates with a US robotics. > >[...] But my understanding >with US Robotics modems is that even though they use V.29 there's >a couple of funny things they do that makes the modem basically only >useful with another USR modem. US Robotics COURRIER HST modems use a proprietary modulation scheme which looks like V.29 in the forward direction with a tiny bit of bandwidth down around 300 Hz for a 300 bps reverse channel without echo cancellation. (a scheme like this has been proposed for standardization, and has gone under the temporary name V.asm - asm for asymmetric.) It runs a hacked version of MNP, which you don't really want to turn off. It sounds like a good idea, but it loses because MNP, even for single characters, is just too slow over the 300bps channel. Telebits or ping-pong V.29 modems will give you much better response time. With the Telebit, it can spoof Kermit or UUCP, instead of having MNP fighting your transfer protocol to slow things down. There are a lot of things I haven't explained in this article, but I didn't want to write 5 or 10 pages. E-mail me if you want more discussion on the technical (as opposed to practical :-) merits of various modems. Peter Desnoyers