AW: [OpenBIOS] OT: Bios access speeds

[Peter Pointner]

On Fri, 30 Apr 1999, Matthias Wächter wrote:

> On Fri, 30 Apr 1999, Stephan Müller wrote:
> 
> > You can take a small ISA-prototype-card and a address-decoder (e.g.
> > 74HC245).
> 
> Sorry, the 74HC245 is no address decoder, it's an 8 bit parallel buffer
> driver (usually used for the data bus).
> 
> > With these 2 things you can connect a flash/eprom/prom/whatever to a
> > specific location in the system-memory (first 16meg, i think on
> > isa-bus)
> 
> You will need a real address decoder for that. If size is the problem, use
> a GAL.
> 

And you should make sure the device is accessible after reset. I don't
know much about the relevant chipsets, but you should definitely make sure
that the processor's reset vector is in the bios address range.

   And you should probably make sure that the ISA bus works after reset. I
never did something with real motherboards, but I hacked something to load
Linux on an embedded system using amd's elan chip (486 core with
integrated peripherals). And the elan has only a single chip select
configured after reset, to use ISA, the bios has to activate it before.

Peter


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