compatible flash chips

Jeff Noxon jeff at planetfall.com
Fri Aug 22 17:07:00 CEST 2003


The best thing to do is compare data sheets.  Also, look at the
linuxbios flash-and-burn program and see what chips it supports.  If
your chip isn't supported, you may need to add the support yourself.

Flash chips tend to vary in operating voltage, programming voltage,
block size, block organization, and bus interface.  There are also
variations to the commands they support.

You *must* make sure they have the same bus interface, i.e., you can't
swap LPC or FWH chips with traditional chips.  The EPIA board uses a
traditional flash chip.  Make sure then pinouts are the same, and the
voltage requirements for the two chips are the same.  Then you can be
sure you're not going to fry anything.

If the block organizations are different, that doesn't matter so much.
As long as you can erase the whole chip and program it, it should work
to boot the system.

Flash chips also come in all kinds of different speed grades.  I may be
wrong, but I doubt the speeds matter much.  The BIOS gets copied into
RAM almost immediately and then runs from there.

Also, note that programming flash chips from usermode can be tricky.
Some chips are very sensitive to timing and may not program correctly.
I recently had problems programming a winbond chip until I removed all
the print statements from flash-and-burn!  The moral of the story is
to always verify that the flash was done error-free.

It might be worth the $20 to buy a Bios Savior, and you'll get the
same SST chip with that...

Regards,

Jeff

On Fri, Aug 22, 2003 at 01:49:48PM -0600, Nathanael Noblet wrote:
> Hello,
> 	I just received my EPIA 800 and am itching to get it up and running 
> with freebios. I have flash parts for a board I was previously working 
> on. I'd like to know if they are compatible, they are the same form 
> factor (as in PLCC chips). The one in the board is a SST 39sf020a, and 
> I have Winbond w29c020cp90b. How do I know if they are compatible? I'd 
> rather not flash this and it not work, and then not be able to do 
> anything with it...



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