suggestion on ordering things

[Ronald G. Minnich]

I think memory startup should happen first or early. On the new machines
you can't use ram til you power on memory.

ron

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[Matthew Sullivan]

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.

You should test and initialize the first 64k of RAM before you attempt to start any other ROM's (eg VGA, SCSI or Netboot).  Most size and test the remainder of the RAM immediately before or after starting the VGA BIOS - remembering that the Primary VGA BIOS is usually initialised in the early part of the POST.

Matthew

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
More Computer Terminology
-=-=-=-=-=-=-=-=-=-=-=-=-
Bits: The things scattered all over the floor after you drop your computer down the stairs.

[Ronald G. Minnich]

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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[David Christensen]

If you're looking for an idea on what to do during BIOS power-on self-test
(POST) you may start with this link:
http://www.phoenix.com/pcuser/userman.pdf

Starting on page 35 you'll get a listing of POST codes and approximately
what occurs at each code.  Unfortunately the codes are listed in numerical
order, not the order that they occur, but you should be able to figure out
which codes require RAM and which don't.  Memory sizing occurs at POST code
28h, then you probably want to initialize RAM very soon afterwards by
writing a known value to every memory location to clear up any parity/ECC
errors that may be present because the contents of DRAM are not known at
power-up.

Dave

-----Original Message-----
From: [e-mail]
[mailto:[e-mail]]On Behalf Of
Ronald G. Minnich
Sent: Monday, February 14, 2000 7:37 AM
To: [e-mail]
Subject: [OpenBIOS] suggestion on ordering things

I think memory startup should happen first or early. On the new machines
you can't use ram til you power on memory.

ron

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