Re: A89: Re: Writing to Flash ROM

To: assembly-89@lists.ticalc.org
Subject: Re: A89: Re: Writing to Flash ROM
From: Jeff Flanigan <propalo@yahoo.com>
Date: Tue, 6 Jun 2000 01:30:49 -0700 (PDT)
Reply-To: assembly-89@lists.ticalc.org

--- Zeljko Juric <zjuric@utic.net.ba> wrote:
> 
> I am not sure that you are jumping to the correct
> place
> in the ROM which satisfies all necessary conditions
> to
> disable the protection (these condition are not
> emulated
> correctly in VTI). Do you know exact conditions
> which
> must be satisfied to disable the Flash protection?

I draw my sources from Johan Borg's flashrom.txt, and
TI92 and TI89 Structures and Variables by Gareth
James.  According to them, you must (while executing
code in 0x200000-0x20FFFF, 0x212000-0x217fff or
0x21a000-0x21fff0f) write to anywhere in
0x1c0000-0x1f0000.  The routine that I use for writing
to 0x1c0000-0x1f0000 is located at 0x2128ae.

One thing I could possibly be doing wrong is not
executing code long enough in 0x200000-0x20FFFF,
0x212000-0x217fff or 0x21a000-0x21fff0f to disable the
protection.  Also, I have not checked that my routine
that programs the flash mem works with the non
protected flash mem, although I am 99% sure it works
(I got it from someone else).

-Jeff Flanigan

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