[A83] Re: What is the problem with flash writes (in general)


[Prev][Next][Index][Thread]

[A83] Re: What is the problem with flash writes (in general)




You should write a receive program for your calc, which displays what byte
you received from the graph link software. Then by examinig the TI-OS and
see how that would respond you can make your receive program a bit complexer
as to receive and examine more bytes. And so you continue. And then
(theoreticaly) you should be able to find what format your OS-file should
have.
------------
Hmm, this sounds a bit to easy maybe, but at least somebody could try it
out.

----- Original Message -----
From: "Tijl Coosemans" <tijlc@hotmail.com>
To: <assembly-83@lists.ticalc.org>
Sent: Monday, July 09, 2001 9:55 PM
Subject: [A83] Re: What is the problem with flash writes (in general)


>
> > From: "Hyperbyte" <hyper@hysoft-automation.com>
> >
> > > > From: "Hyperbyte" <hyper@hysoft-automation.com>
> > > >
> > > > Simply put, no user-program can do it.
> > > >
> > > > Explanation:
> > > > The flash chip has a "write enabled" line,
> > > > only if this line has specific signal, one can write to the flash
> > > >
> > > > Now one could simply set this signal, if TI hadn't prevented that,
> > > > they've somehow made it only possible for certain OS Rompages to
> > > > set that value.
> > > >
> > > > (I think it's kinda obsolete now, since TI's released the app
signing
> key,
> > > > but I doubt they'll insert _FlashWE and _FlashWD romcalls in new
> OS'es)
> > > >
> > > > You could hardware hack that WE line, but then your program wouldn't
> be
> > > distributable...
> > >
> > > Or, you can make your own OS, I mean TI-OS, which implements a routine
> that
> > > enables writing to flash......
> >
> > How are you planning on signing that custom 'TI'-OS?
> >
> > AFAIK, OS'es need to be signed too, and I can't see how TI would be
> > as stupid as to sign it's OS'es with the freeware private key.
>
> It's all theoreticaly of course, but when you attempt to send an OS to
your
> calc, your calc checks if it's a valid OS right? So can't you check that
> code and see how that's done? It's also possible that the graph link
> software checks a few things, but writing your own PC program that sends
> data and doen't check anything shouldn't be that difficult.
>
>
>



Follow-Ups: References: