Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!sdd.hp.com!caen!uwm.edu!lll-winken!telecom-request From: johnl@iecc.cambridge.ma.us (John R. Levine) Newsgroups: comp.dcom.telecom Subject: Re: Hayes Wins Damages on its Command Set Patent Message-ID: Date: 19 May 91 18:54:34 GMT Sender: Telecom@eecs.nwu.edu Organization: I.E.C.C. Lines: 33 Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 11, Issue 379, Message 1 of 10 In article is written: > The ability to do that in a way that guarantees that escape to > command mode won't accidentally be invoked by the data stream would > be difficult (I can't think of a way) without timing and a unique > string being an essential feature of the escape from data mode. The other approach is to reserve some character sequence to mean switch to command state, and to have some way of protecting that sequence if it appears in data, most typically by doubling the first character of the sequence. This works perfectly well, and is what one does with synchronous modems, but means that the communications software on each end has to do some of the filtering, while the timed technique has the advantage of the escape sequence being so unlikely in the normal data stream that no protection is necessary. > My feeling is that the Justice Department, gutted by Reagan and > Bush, really should be filing anti-trust suits against corporations > that participate in monpoly by litigation. The whole point of a patent is to allow monopoly by litigation (or more typically by the threat thereof) for a limited period. On the other hand, someone pointed out that the way you escaped to command mode on an arpanet PAD was delay-@-delay, which is basically the same as Hayes approach and was almost certainly invented and more important published earlier. I haven't heard whether that example was presented to the court. Regards, John Levine, johnl@iecc.cambridge.ma.us, {spdcc|ima|world}!iecc!johnl