[OpenBIOS] suggestion on ordering things

Ronald G. Minnich rminnich at lanl.gov
Mon Feb 14 10:31:54 CET 2000


On Mon, 14 Feb 2000, Matthew Sullivan wrote:

> Hi,
> 
> "Ronald G. Minnich" wrote:
> 
> > I think memory startup should happen first or early. On the new machines
> > you can't use ram til you power on memory.
> 
> To give a little clue (you may already know this) you need to
> initalize and test the first 64k block of RAM.  Upon successful
> completion of the test you can then use this memory and start sizing
> the rest of it...  Most current BIOS's (Pheonix Award and AMD for
> example) test the first 64k before completion of the 20th 'POST' test
> (often in early AMD and Award it was the 5th or 6th test) the rest of
> the RAM test and sizing happens at various other stages depending on
> the BIOS and board.

Yes, but it is harder than that now. You have to physically power on the
dram from the 443 bridge (see the 82443gx bridge datasheet, registers
76-77). you can't go init ram until you've done an 'interesting' sequence
of things that takes over 200 microseconds to wrap up. 

thanks

ron

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