Re: A89: installing custom ROMs (was: Linux port for 89/92)

To: assembly-89@lists.ticalc.org
Subject: Re: A89: installing custom ROMs (was: Linux port for 89/92)
From: Olle Hedman <oh@hem.passagen.se>
Date: Thu, 22 Jul 1999 01:10:38 +0200
Delivered-To: assembly-89-outgoing@towerguard.unix.edu.sollentuna.se
Delivered-To: assembly-89@lists.ticalc.org
References: <19990716144957.A3598@student.liu.se>
Reply-To: assembly-89@lists.ticalc.org

Johan wrote:
> 2. If the boot loader refuses to install our ROM, *we* do it. We can write a
> small asm prog that disables ROM protection and downloads the code from the
> computer. No boot loader will ever get the chance to check if the encrypted
> checksum is correct, because it is verified during the download only (I think
> / hope). This method is very unsafe (overwriting the certificate area by
> mistake would be *fatal*) and everytime we want to upgrade our code, we must
> first reinstall the old TI-ROM to be able to run the asm installer.
> 
> //Johan

this second alternative should be the simplest I think.. If we first clearly
identify wich areas we cant overwrite.. wich probably should be easier than
cracking RSA encryption.. (or less time consuming at least :)
And we don't need to reinstall tios, if we include our own installer in the code
we upload.

//Olle

References:

A89: installing custom ROMs (was: Linux port for 89/92)

From: Johan <johei804@student.liu.se>

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