Re: A89: Overwriting ROM (was Re: Linux Port)


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Re: A89: Overwriting ROM (was Re: Linux Port)




>it is amazing that the majority of people who actually know the
>specifications of this 'secret' are the only ones who would really even
know
>how to make a virus...and this wormhole guy actually proves it...who is to
>say that he doesn't intend to send a major tivirus to ticalc or some other
>major site (no offense intended) ...and who is to say that others who know
of
>it such as mr. vassor or mr hedman are not secretly working on viruses =)
>(again no offense intended)...my point is that it is not a secret anymore;
it
>is pretty much already shared w/ every top ti89 programmer while those who
>may perhaps learn something from 'the bug' are kept in the dark...

Who is to say that Wormhole actually DID write a virus? I believe it, but I
certainly don't have any proof (at least, not that I'm willing to run =)
>From what I know, creating an Illegal Instruction error intentionally can
cause the Flash ROM to give up its protection and let someone write to it.
The portion of the ROM containing the Flash upgrade code cannot be
overwritten; however, the calculator checks a certain byte every time it
receives a Flash transmission and will not accept it unless that byte is set
in a certain way.  That byte IS overwritable, and by simply overwriting that
byte the Flash ROM cannot be upgraded.  Then screw up a vital part of the
ROM on the calc and it can't be fixed. . . I'll see if I can get him on the
list. . .