🚀 go-pugleaf

Just in case anyone else comes across this peculiar problem...

System Board PCI Bus Mainboard 486
       3 PCI
       4 ISA
       Supports P24T, DX100
       Write Back Cache

Intel DX-100
16MB 60ns non parity RAM
Bus Logic 545S SCSI card with default settings
Oak Technology VGA Card (256K)
IBM 540 MB SCSI HD
SEAGATE 400 MB SCSI HD
1.4MB Floppy

The  *** DMA TEST FAIL !! *** message appeared just at the  point 
that the SCSI hard was about to show what was on the SCSI bus.

I  ended  up  clearing CMOS, which did nothing. I  ran  PC  TOOLS 
SI.EXE  and  tested  the  DMA controller  and  CPU  and  rest  of 
motherboard.  All  passed.  Then tried  the  VGA.  Something  odd 
happened  on  the colour bar display, almost as  if  the  display 
wasn't  synchronising. So, I tried another video card,  a  Compaq 
ISA VGA card (1988). On power on, there were two slow bleeps, but 
no DMA fail message. When I put the OAK TECHNOLOGY card back into 
the  last ISA slot, I just got a white grid on boot up.  Changing 
the card to the next slot, and there was no DMA FAIL message.

Now  it  *may*  be  dirty  ISA slots I  guess.  It  *may*  be  an 
intermittent  fault  in the DMA controller, or maybe  some  other 
intermittent  motherboard problem. Anyone ever seen this sort  of 
thing before? Why should a video card contribute to a DMA failure 
at the point the SCSI card was scanning its bus?

-- 
David Longley