Everex Tape-Motherboard Conflict under Unix but not DOS

[Rock Kent]

Synopsis:    I have been using an Everex streaming tape under Microport
             V/386 for two years without any problems.  I just installed
             a new motherboard and now the system locks up if I try to
             access the tape under Unix.  It works fine, though, under
             DOS.  I'm clueless.  Any ideas??

System:      Motherboard:  Micronics 20mhz 80386 (OLD)
	    	  	   Caching Technologies 33mhz 80386 w 64k cache (NEW)
             Tape:  Everex EV831, 125mb streaming tape.  (Wangtek 5125EN Drive)
	     Software:  Microport System V/386 version 3.0e with FAS.

The system has been stable for about two years.  I have regularly
backed up using find and afio.  While throughput has been low, there
have been no functional problems.  I recently replaced the mother
board.  Every attempt since then to access the tape has:
   - locked the system.  No response to any keys, no changing virtual
     consoles, no sysreq, nothing!
   - left the disk access light on with no sound of head seeks coming
     from the drive.

I've tried changing the DMA channels (1,3) and interrupt vectors(2,5).
All combinations work with the Everex supplied tape software under
DOS.  All combinations lock the system under Unix.  I've checked and
double checked to make sure that there are no interrupt conflicts.

I would greatly appreciate comments from those of you who've had to
deal with a problem like this.  I seem to remember a general
conversation on caching mother boards, but it seems odd to me to
believe that the board is only affecting operations under Unix and not
also under DOS.  I really don't know where to go from here.

Thanks.

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*Rock Kent    rock at rancho.uucp        POB 8964, Rancho Santa Fe, CA. 92067*
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