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

To: <assembly-83@lists.ticalc.org>
Subject: [A83] Re: What is the problem with flash writes (in general)
From: "Ronald Teune" <rtwolf@gmx.net>
Date: Sat, 14 Jul 2001 18:55:36 +0200
Reply-To: assembly-83@lists.ticalc.org


A bit late probably, but...

-----Original Message-----
From: Tijl Coosemans <tijlc@hotmail.com>
To: assembly-83@lists.ticalc.org <assembly-83@lists.ticalc.org>
Date: dinsdag 10 juli 2001 0:34
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?

Yes, with calc2calc os-sends too.

>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.


--Ronald