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Newsgroups: comp.os.386bsd.bugs Path: sserve!newshost.anu.edu.au!munnari.oz.au!constellation!convex!convex!cs.utexas.edu!sdd.hp.com!col.hp.com!csn!hellgate.utah.edu!fcom.cc.utah.edu!cs.weber.edu!terry From: terry@cs.weber.edu (A Wizard of Earth C) Subject: Re: Problems with patchkit 0.2.4 Message-ID: <1993Jul25.220104.13519@fcom.cc.utah.edu> Sender: news@fcom.cc.utah.edu Organization: Weber State University, Ogden, UT References: <1993Jul20.012738.2952@fcom.cc.utah.edu> <CAHvz0.38s@cyb.cojones.com> <BLYMN.93Jul25173659@siren.awadi.com.au> Date: Sun, 25 Jul 93 22:01:04 GMT Lines: 39 In article <BLYMN.93Jul25173659@siren.awadi.com.au> blymn@awadi.com.au (Brett Lymn) writes: [ ... modems that lie about the number of CPS they can transfer ... ] >In this case you definitely need the flow control because the data you >pump at the modem may not be uniformly compressible so you can overrun >the modem. Use either stty crtscts or get a slattach that sets this >for you. The initial issue that has yet to be addressed is that the current CTS/RTS implementation in the driver matches neither the Bell-103c standard, nor matches what Telebit and other modems expect. It also neglects the fact that many compressing modems (but not Microcomm or Telebit) put less RAM in the modem than they should, and then, in clear violation of the MNP-5 definition, turn on flow control *in band* when MNP-5 is on, with no way to turn it off. These modems can *never* be used at high data rates with binary data, since 1/128th of the data stream (statistically) will match the in-band flow control characters "^s" and "^q". The only choice these manufacturers would have would be raising the price of their modems to match their competitors by way of adding enough RAM that buffer overruns don't occur... then why buy a knock-off when you can buy a real Microcomm (since they invented MNP)? In modems, you will definitely get what you pay for. In any case, it is not safe to use CTS/RTS flow control until the driver has been fixed, and it hasn't been fixed yet. When* it has been fixed, *then* your advice will be applicable. Until then, don't set the connection to the modem to 19200 baud unless you *know* the modem will *always* be able to push 1920 characters a second down the line. Terry Lambert terry@icarus.weber.edu --- Any opinions in this posting are my own and not those of my present or previous employers.