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From: sip1@sam.spc.uchicago.edu (Timothy F. Sipples)
Newsgroups: comp.windows.ms
Subject: Re: Communications Programs for Windows
Message-ID: <1991May21.041546.17046@midway.uchicago.edu>
Date: 21 May 91 04:15:46 GMT
References: <1991May20.140302@geohub.gcn.uoknor.edu> <1991May20.204430.19873@midway.uchicago.edu> <12308@uwm.edu>
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>>A more general question: is there any way to prevent Windows when operating
>>under standard mode from losing characters when receiving a file (via, say,
>>ZMODEM) in the background?  Any moderately busy hard drive activity and
>>the transfer is terminated.  Formatting a floppy?  Forget it.
>>I haven't tried it, but does YMODEM fare any better?
>I am also running a 286 under standard mode.  I haven't experienced this
>problem at all.  Although, I'm using WinQVT, one of the worst comm programs
>I've *ever* used.  Maybe that's all that WinQVT is good for.   ;-)
>I start a ZModem Dl and I click on the minimize box.  WinQVT goes bye-bye
>and I am able to run other apps.

To elaborate: to the best of my knowledge, an 80286 machine, when switching
between real and protected modes (in either direction) experiences a
brief moment of time in which all interrupts are disabled.  This can
possibly cause problems in losing characters arriving at the serial
port.

The best solution is to either stay in protected mode all the time
(i.e. buy OS/2 or Xenix) or to get some intelligence into the serial
port (e.g. buffered UART, Hayes ESP, etc.)  Or find a way to avoid losing
characters during the short interval between switches.

Some possible peculiarities of my system: I use Hercules, an SCSI
hard drive, and 640K + 2176K extended.  I've set STACKS=0,0 in CONFIG.SYS
(perhaps I should turn it back on?) and I've got SMARTDRV.SYS installed.

To reiterate: the problem only occurs with semi-heavy access of any
disk device.  (Although heavy is a relative term -- I don't think it's
that heavy.)  For example, a launch of Pagemaker followed by a launch of
Word for Windows will be nearly enough to have ZMODEM time out.
Formatting a floppy, as I mentioned, is out of the question.

Thoughts?

T.F.S.						sip1@quads.uchicago.edu
Timothy F. Sipples				sip1@sam.spc.uchicago.edu