[comp.sys.ibm.pc] Floppy DMA Fails with 386^max

royf@attctc.Dallas.TX.US (Roy Frederick) (11/29/89)

I am using a Compuadd 386-25 (not the model 325, the older one).  The
system came with a utility package (Integrator) and an EMS manager
(386limit).  The utility package contains a backup program that does
simultaneous DMA to the hard and floppy drives.  I am using a 2 mb
AT type extended memory board (in a 16 bit slot, of course) - I
haven't yet sprung for the SIMMS to give fastest memory.

The backup utility works OK if 386limit.sys is not being used and the
system is set to the slowest speed (8 mhz).  With 386limit installed,
the system hangs when the backup utility is used.  386limit is
produced by Qualitas.  I tried 386^max - same problem.  I tried
Fastback and Backit 3.1 - same problem.  The hard disk access is ok -
but any access to the floppy fails (for example: format using
backit).

Even without 386^max or 386limit - the system hangs unless the speed
is set to 8 mhz.  Sometimes the failure is a "Priviledged operation
exception"; sometimes just a lockup with the floppy drive light on. 
Sometimes the system doesn't crash - the backup program tells me the
floppy disk is defective - can't read track 0.

A DMATEST program supplied with Backit also fails.  Not too
gracefully - usually with a lockup.

I would appreciate any ideas y'all would care to share!

Roy Frederick (royf@attctc.UUCP)
Dallas County Data Services  (214) 653-6340
504 Records Bldg.
Dallas, TX 75202