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

To: assembly-89@lists.ticalc.org
Subject: A89: installing custom ROMs (was: Linux port for 89/92)
From: Johan <johei804@student.liu.se>
Date: Fri, 16 Jul 1999 14:50:01 +0200
Delivered-To: assembly-89-outgoing@towerguard.unix.edu.sollentuna.se
Delivered-To: assembly-89@lists.ticalc.org
Reply-To: assembly-89@lists.ticalc.org


Ok, let's face it: Factoring a 512-bit number is a very large scale project
that would take *ages* for us... :(

I see two ways to go:

1. If we can't break TI's key, we create our own. We can install our own key
in the certificate area and then suddenly the boot loader will be very
friendly to us. The only problem left for us is to figure out the exact
format of the certificates. This method will be safe since we use TI's
installation code.

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

Follow-Ups:

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

From: Olle Hedman <oh@hem.passagen.se>