Re: A89: rom patching

To: assembly-89@lists.ticalc.org
Subject: Re: A89: rom patching
From: Olle Hedman <oh@hem.passagen.se>
Date: Sat, 01 Jan 2000 16:30:33 +0100
References: <386C347F.6AC7D70@drrobin.yi.org> <386CF035.382BD311@calc.org>
Reply-To: assembly-89@lists.ticalc.org

$fff8 you say?
It is probably writeing command to the flash chip. There is no command
following that pattern, that I can find though. $FF is though resetting
the flash to normal read-mode, wich might be what you see.
In that case, the address isn't really important, as long as it is in
the flash memory area.
$210000 is the first byte of the writable flash, and also the first byte
of the second block of flash. AU is probably writeing some commands to
it.
As far as I know, you should _not_ change any data between $210000 and
$212000, (the key and maybe the serial numbers and stuff are here)
I have the exact memory position the boot seems to jump to at home, but
not here, sorry. somewhere near $218000 if not my memory is wrong.
Ofcourse, if you want to change something in the block $210000 - $21ffff
you have to erease the whole block and write it again, so if you are to
do this, be really really shure you rewrite it correctly or you will be
fucked. (or your calc at least, and not litterly speaking, so you can't
use it to loose your virginity, sorry)

//Olle
(the pdf descriebeing how the flash rom works, is to be found at
http://alh.dhs.org/ti89/ )

Scott Dial wrote:
> 
> Oh yeah, this reminds me. Does anyone know what the significance of
> $210000.w? I assume this is the location that is called on boot or
> something because that is what AU tries to write $FFF8.
>

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