Path: utzoo!attcan!uunet!mcvax!hp4nl!uva!betty!dik
From: dik@uva.UUCP (Casper H.S. Dik)
Newsgroups: comp.sys.ibm.pc
Subject: Re: MS-kermit loosing characters at 19200 bps
Message-ID: <643@uva.UUCP>
Date: 18 Feb 89 00:52:00 GMT
References: <667@pkmab.se> <943@starfish.Convergent.COM> <675@pkmab.se>
Sender: news@uva.UUCP
Reply-To: dik@uva.UUCP (Casper H.S. Dik)
Organization: Faculteit Wiskunde & Informatica, Universiteit van Amsterdam
Lines: 51

In article <675@pkmab.se> ske@pkmab.se (Kristoffer Eriksson) writes:

>>> When I use MS-kermit (ver 2.3*) at 19200 bps on an ALR 386/220 or at
>>> 9600 bps on a Compaq Deskpro 286, and type anything at the same time
>>> as I receive something, kermit beeps at me an looses received characters.
>> 
>My principal use of MS-Kermit is indeed for connecting to UNIX systems. And
>indeed I usually use ixon -ixoff ixany. But I've tried your advice now, and
>it didn't help at all.
>
>I made some more extensive tests, and found that Kermit starts beeping and
>loosing characters almost immediately when I type anything while output is
>going on to the screen, but starts emitting xoff:s much later. (I do have
>flow control set to xon/xoff in Kermit.)
>
>I really wonder why Kermit beeps. It can't just beep by accident. It should
>meen something.


Kermit beeps on purpose. When it gets an serial-i/o interrupt it checks
the status of the UART and if it indicates it lost a char, Kermit
outputs a beep. (I have the sources - I wondered what the beep meant too)

The problem has nothing to do with flow control. In the time it takes to
scroll the screen, more than one character can arrive.
I believe the problem lies in the disabling of interrupts during scrolling,
Kermit calls the Bios to scroll with INT 10H. This disables interrupts.

Currently I use a TB+ with Kermit on a 8MHz PC-XT clone.

The problem occurs when I use 19200baud on a 24 * 80 screen.
It also occurs when I use kermit at 9600 on a 24 * 132 screen.

In tektronics mode, no UART overruns occur, indicating that Kermit can
handle these high speeds with flow control.

My diagnosis was more or less confirmed when I tried to use Procomm 2.4.2.
Same problem there.

I know this isn't much help but now you know what's wrong.

>Kristoffer Eriksson, Peridot Konsult AB, Hagagatan 6, S-703 40 Oerebro, Sweden
>Phone: +46 19-13 03 60   !  e-mail: ske@pkmab.se
>Fax:   +46 19-11 51 03   !  or      ...{uunet,mcvax}!enea!kullmar!pkmab!ske


--cd

Casper H.S. Dik
University of Amsterdam     |		      dik@uva.uucp
The Netherlands             |                 ...!uunet!mcvax!uva!dik