Path: utzoo!attcan!uunet!lll-winken!lll-tis!helios.ee.lbl.gov!pasteur!ucbvax!ucf.CSNET!goldfarb%hcx9
From: goldfarb%hcx9@ucf.CSNET ("Benjamin I. Goldfarb")
Newsgroups: comp.protocols.misc
Subject: Re:  About Protocols for File Transfer
Message-ID: <8806061401.AA04016@hcx9.ucf.edu>
Date: 6 Jun 88 14:01:35 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 20

>There isn't much of an upper bound on the number of extra
>characters that might be inserted into the stream.  Would you
>believe several hours' worth of "UUUUUUUUUUUUUUUU" at 1200
>bps?  (I enhanced error recovery procedures after that one.)
>That's one modem's rendition of dial tone.
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OH YEAH?  More likely the "UUUUUUUUUUU" was an erroneously
initiated test mode in the modem in question.  Racal-Vadics are
notorious for this but the feature can be disabled by either
a dip switch or a strap option.  A stream of ASCII U's makes for a
good digital test because U is 01010101, so a stream of them
creates a nice, big, fat square wave on a scope.

Sorry to be so picky, but I never saw a modem "render" a 
dial tone.

			Ben Goldfarb
			University of Central Florida
			goldfarb@ucf-cs.ucf.edu
			{decvax,peora,uflorida,codas}!ucf-cs!goldfarb