*BSD News Article 27056


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Newsgroups: comp.os.386bsd.questions
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From: tucker@sde832.vf.ge.com. (Tucker Clark)
Subject: I sing the MODEM blues
Message-ID: <1994Feb7.152038.28727@knight.vf.ge.com>
Keywords: modem
Sender: news@knight.vf.ge.com
Nntp-Posting-Host: sde832.mdso.vf.ge.com
Reply-To: tucker@mdso.vf.ge.com.
Organization: Martin Marietta FAA Systems
Date: Mon, 7 Feb 1994 15:20:38 GMT
Lines: 58

Alas, having read the FAQ, many past usenet threads, and yes, even the kernel
sio.c et.al. sources, I am still unable to get my Zoom 144 internal modem 
to work with FreeBSD RELEASE 1.0...

Setup:
	o  486DX2/66 8MBRam
	o  144 modem (reported as 16550A UART) on COM1 (really 0)
	o  FreeBSD GENERICAH kernel (sio driver installed)
	o  tty00 created by running MAKEDEV in /etc

Symptom(s):
	o  I run kermit (binaries ftp'd from freebsd.cdrom.com)
	    > set line /dev/tty00 
	    > set flow rts
	    > set speed 19200  (substitue any valid speed here -- i tried em all)
	    > connect
	     ...
	     (currently connected and talking to modem... "here's where the 
		trouble begins..")

	     I type an 'A'    (I see nothing printed on console)
	     I type a 'T'     (The 'A' appears on the console)
	     I type a 'D'     (The 'T' appears on the console)
	     I type a 'T'     ( you get the picture... )
	     ... I press <return>  (the modem dials! and connects )
		
	      (I see no data from remote modem until I transmit data (press a key))
		Also, if I press a key while the modem is dialing, it hangs up.
		
	o  The same thing happens with 'tip'.

Things I tried:
	o  Added numerous printf's to the sio.c driver to annotate the 
	   LineStatus (overflow/parityerror/break/frameerror) register.
	   This revealed that there were OverRun errors occuring when the 
	   modem attempts to transmit data to the UART.  When the UART's
	   FIFO is enabled, these OverRuns only occur when a remote modem
	   is sending a stream of text (more than 14 chars i assume).  
	
	o  I then hacked the code to disable the UART's FIFO (thinking 
	   that maybe the UART was buggy.  No better.  Now, I get OverRun errors
	   after every character I type.  Presumably, the modem is trying
	   to echo the character back, but the siointr() routine is not getting
	   called to read the character so it sits in the UART's receive buffer
	   register.

Now, I'm lost.  I probably overlooked something really dumb (wait, did I plug
it in? oh, yeah.)  Anyways, can someone provide any assistance?  I'm rather
hesitant to admit it, but the same modem works under (don't make me say it) 
Windoze.
Thanks in advace,  Clark      |   email: tucker@mdso.vf.ge.com