Problem with 256K BIOS build

[Wallace I. Kroeker]

Hello,

I have the OpenBIOS working for both 64K and 128K builds.  However, when I
try to do the 256K I get nothing.

I came across some documentation that claims that "32KB of BIOS expansion
range from 0C0000H to 0C8000H is typically reserved for the video BIOS
expansion ROM"  (source is M-Systems DiskOnChip 2000 data sheet).  If this
is true then how do you fit the 256K bios in the system as we will need the
range from C0000H all the way up to FFFFH and manage to avoid a collision
with the video BIOS expansion ROM.

I am using loadbios for testing and have sucked out the BIOS that comes with
my system.  This works fine.  However, the OpenBIOS build of 256 doesn't.

Any ideas on what we need to do?

Wallace

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[Ronald G. Minnich]

On Wed, 16 Feb 2000, Wallace I. Kroeker wrote:
> I came across some documentation that claims that "32KB of BIOS expansion
> range from 0C0000H to 0C8000H is typically reserved for the video BIOS
> expansion ROM"  (source is M-Systems DiskOnChip 2000 data sheet).  If this
> is true then how do you fit the 256K bios in the system as we will need the
> range from C0000H all the way up to FFFFH and manage to avoid a collision
> with the video BIOS expansion ROM.

for 256K, you use the top of the 1M hole at 15M. For more, you use the
top of the 2M hole at 2^32-2^20.

It appears that bioses run for a while in bigreal mode, then shift to real
mode when they boot the os, at which point they can't really access 256K
:-(

ron

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