common flash hw write enable methods

Jeremy Jackson jerj at coplanar.net
Mon Dec 2 14:34:00 CET 2002


One i430TX board I have (Tyan S1571) had the DIP32's (Atmel AT29C010A) OE#
in the normal place (ISA MEMR#), but the WE# at ISA SMEMW#.  So you had to
read from the high window, and write to the low.  annoying to alter
/dev/bios driver, so I removed the jumper and soldered WE# to ISA MEMW#.

Regards,
Jeremy

----- Original Message -----
From: "Andrew Kohlsmith" <akohlsmith-linuxbios at benshaw.com>
To: <linuxbios at clustermatic.org>
Sent: Sunday, December 01, 2002 9:59 PM
Subject: common flash hw write enable methods


> After some head-scratching, I realize that the hardware RP# and VPP are
tied
> together, and at a logic low, preventing any flash attempts.  These are
pins
> 10 and 11 on the TSSOP part.  :-(
>
> Now I imagine that these are tied to a MOSFET to +12V which is run off of
a
> GPIO pin.  The question is, without tracing an 8-layer board out to try
and
> identify how exactly reflash is enabled, how to reflash this?
>
> I can always cut the traces and hard-wire to +12V but I'd like to see if I
> can't do this programmatically.  I have a number of boards I want to use
and
> hardware hacking is something I'd like to avoid doing if possible.
>
> Now I know that every motherboard is different and that there may be other
> things locking me out, but generally speaking is there an "industry
standard"
> way of enabling/disabling BIOS reflash?  It's currently a PhoenixBIOS, so
I
> imagine if I located a reflash tool and ran it in a Bochs session with a
lot
> of I/O debugging I could figure out what it's doing but before I embark on
> that I'd like to see if anyone has any hints that may save me a lot of
time.




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