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Modem Incongruency

emart
emart asked
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Last Modified: 2010-03-17
I just installed Slakware 96 and everything work well except my dialup connections to my school and ISP.  When I login to my school using minicom, I lose quite a few charaters in the transmission.  When I try to run pine at school, you can imagine the confusion.  I have set no echo, vt102 mode, and my setserial command in the rc.serial is manual with spd_vhi at the end because I have a USRobotics Sportster 28.8.  Also when I run seyon, I notice the default speed is 9600, and when I change it to 38400, I can't save it.  Starting up seyon again brings up the 9600bps.  This has ramifications for problems with my ppp connection which I won't go into, except to say that minicom keeps reporting the message: 'cua2: x input overruns' (with x < 5).  Thanks for your help.
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Hi,

What you most likely have is a 16450 UART serial port or some other inadequate UART chip.  You can verify this by looking at the output of the "dmesg" command.  Look for the lines that say tty at the beginning-- it will tell you what type of UART it is.  Basically, at higher serial speeds, the buffers of some UARTs get overrun.

Most of the time you can upgrade your UART chip in place to take advantage of higher serial speeds.  You can consult your local PC-superstore or whatever to get details for your hardware.

Until you can get the upgraded serial chip, you are going to have to connect at lower speeds-- just set your serial port down to 38400 or so and it should stop losing data.

If an inadequate UART is not the problem, then you most likely have a cable problem.  You can try changing serial cables if you like.  But I've had the UART problem before, and it's exactly the symptoms you are describing.

Hope this helps...

Mart

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