AW: AW: [OpenBIOS] OT: Bios access speeds

James Oakley jfunk at
Mon May 3 03:42:46 CEST 1999

Stephan Müller wrote:
> > >Ah!  Very much like video memory or adapter RAM...  **NOW** I
> > understand the
> > >ISA bus speeed question and why it was important!!
> >
> > I was looking through my motherboard manual today, and I happened to see a
> > block diagram of the Intel GX chipset.  According to the block
> > diagram, the
> > BIOS uses the same interface into the chipset as the ISA bus.  While the
> > BIOS may not actually be attached to the ISA bus, it is accessed
> > in the same
> > way by the chipset (and, therefore, the CPU).
> >
> > Of course, this was a rough block diagram and, besides, what do I know?
> The BIOS is normally connected directly to the ISA bus. That is why, if the
> ISA-Bridge is damaged, your Board can't even boot with PCI-Cards.

Wow, didn't expect OB traffic to increase this much, considering the
recent lull.

Yes, the BIOS is connected to the ISA bus, I verified that with a

All of the flash pins can be connected on the card to the ISA bus except
for /ce. It's easiest to hijack it from the original flash socket.

I have that part of the schematic completed, not that there's any design
involved, just drawing it takes up time. Glue is not required for the

Glue is, however, required for POST and GPIO. There are two ways to go
with this, and this has been discussed to some degree. Using a GAL is
definitely the cleanest solution. However, is there anybody who wants
one of these who doesn't have access to a programmer? Traditional logic
chips are more accessible to these people. It's still really cheap even
though chip count will increase.

Who agrees/disagrees?

james oakley
jfunk at
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