Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!ames!haven!adm!cmcl2!phri!roy From: roy@phri.UUCP (Roy Smith) Newsgroups: comp.dcom.modems Subject: About "+++" in-band escapes Message-ID: <3695@phri.UUCP> Date: 22 Feb 89 15:48:25 GMT References: <20335@lll-winken.LLNL.GOV> <20736@lll-winken.LLNL.GOV> Reply-To: roy@phri.UUCP (Roy Smith) Organization: Public Health Research Inst. (NY, NY) Lines: 31 Various people have been grousing about the "+++" in-band escape Hayes-like modems have to cut off a call. While I agree in principle that there should be a way to turn it off (and a out-of-band way, like a dip switch), I wonder how much of a problem it is in practice. On every modem I've seen, the escape signal is really "+++". The odds of that happening by random are pretty damn small, and I would be amazed if it ever happened in any kermit, uucp, SLIP, or other machine-generated data stream. I've seen worse. One modem I once had (Century Data Systems 2400?? It's been a long time) used ^T as the escape signal. That's it, just a plain ^T, a single control character, with no timing requirements. Now that's what I call brain-damage! Want to guess how often ^Ts occur in a typical binary data stream (like compressed news batches over uucp?). It's no fun in emacs either. My Trailblazer uses BREAK to signify "go from data to command mode". This is quasi out-of-band. I say quasi because 1) sometimes I really do want to send a break and 2) break is easy enough to hit by mistake on most keyboards. The blazer is at least smarter than most modems; you can configure it about 6 different ways to deal with breaks and if you are in the break-means-escape mode, you just have to type "ato" to go back on line as if nothing happened. The only missing feature is an at command which means "send a real break down the line". Then you could use break as your escape and still be able to send breaks by doing "break, atwhatever, ato". -- Roy Smith, System Administrator Public Health Research Institute {allegra,philabs,cmcl2,rutgers}!phri!roy -or- phri!roy@uunet.uu.net "The connector is the network"