ISC 3.2/harddisk & floppy problems

[karln at uunet.uu.net]

In article <113 at odiehh.hanse.de> marzusch at odiehh.hanse.de writes:
>
>1st problem:
>     When using certain motherboards and ET4000 VGA controllers together
>     write accesses to the floppy disk(s) may fail, however these failures
>   b) Michael told me this problem disappeared when he installed the ET4000 in
>      an 8 bit slot; however this doesn't help much since Thomas Roell's
>      X11 server requires a 16 bit path to the VGA controller


	This brings to mind a problem I was having with _some_ of these video
cards. My SCSI would not boot at all. The problem turned out the the video
card was treating the 16-bit access line of the buss very poorly. There was
a jumper, labeled JP-4, that although undocumented, turned out to force the 
VGA card BIOS into 8 bit mode, same (alomst) as plugging the card into a 8
bit slot. The difference being that the card chipset itself was still acessible
though the 16 bit slot. Only the cards BIOS ran in 8 bit mode. Well this
solved the problem I was having at a considerable loss in X11perf results.

   Further investigation however revealed that I could get the motherboard
to shadowram the VGA BIOS area (C000:0 - C7FF:FFFF, or C000 - C800, or
at least 32k starting at C000, whatever you understand). After that I got
all my performance back and everybody is still happy.

  PS: This also sort of answers a question I posted yesterday (6/13) about
16 Bit VGA compatiblity with Hard Disk Controllers.

  I have seen a ET4000 card that did not have the jp-4 (located on mine, 
in the middle of the board near the buss connector) but seems to work
fine with my exact same set of hardware. I suppose that means that someone
worked it out properly, but it could mean that marginal problems such as
yours just have not shown up yet. This person tends to install from a tape
backup.

  Anyway I hope this helps. These kind of problems really hurt, I know.

			Karl Nicholas



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