Xenix 386-AT system reboots when modem is turned off.

[Perry Minyard 3MTA3]

Im running SCO XENIX 386 2.3.3-AT using a 20MHZ 80386 "DYNA" machine with
4 meg ram, and an 80 meg seagate drive.   I have a Hayes 9600 baud V Series
modem attached to COM1 (tty1A).   

If I turn the modem off while the operating system is up and running, 
the machine does a cold boot.   This also happens on another machine which
is a 33 mhz 80386 using the same type of serial card and modem and OS. 

The card is a generic "SUNTEK" serial card with just one serial port.

The system only reboots though while running Xenix.  If I'm under dos, or
if I issue a haltsys command, then turn the modem off, it wont reboot,
which leads me to believe there is a bug or something in Xenix that triggers
the reboot when the modem is turned off.

I also have the same type of serial card and 33mhz machine running at my office
under SCO XENIX 386 2.3.3 (GT Version (for a SCSI drive), and it doesn't reboot
when the modem is turned off.  All three computers, modems, and serial
cards are the same brand.  2 of the 3 computers are 33mhz 80386, and the third
is a 20mhz.  Two of the three (20mhz and 33mhz) reboot when the modem is turned
off.  They both are using the AT version of Xenix, which leads me to believe
that this problem is not hardware specific and is occurs in the AT, not GT
version.

   
Has anyone else had similar experiences or know of a fix for this?  

Thanks,
Perry Minyard

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