Since OS 3.0.2.1791, minimal installable OS version was set to 3.0.2.1785. This number is written in NAND outside the filesystem, and is not cleaned by any official menu.
It was impossible for your Nspire to go back to OS 3.0.1.1753 for example.
But some of us wanted to keep the possibility to go back to that OS.
Indeed, OS 3.0.1 had:
- some flaws fixed on newer versions
- the possibility to open partialy encrypted Lua scripts
- a working Lua print() function which let you control external peripherals (http://tiplanet.org/forum/viewtopic.php?t=7883) thanks to the RS232 port of the dock connector
Today thanks to Bsl and TI-Planet, you've got the choice with our new Ndless program: downgradeCX! ;D(http://www.omnimaga.org/Themes/default/images/gpbp_arrow_up.gif)
(http://i43.servimg.com/u/f43/13/23/13/53/27-03-10.png)
Like Nleash and downgradeFix, downgradeCX just erases the NAND page containing the minimal installable OS version.
But it's also better in the following ways:
- Unlike Nleash, downgradeCX doesn't remove the OS. You can go on using the OS untill you decide to downgrade, or even change your mind and in the end not downgrade at all. ;D(http://www.omnimaga.org/Themes/default/images/gpbp_arrow_up.gif)
- Unlike downgradeFix, downgradeCX doesn't need the OS to be removed or a specific Boot2 version to be flashed - which required an external USB/TTL2 interface! ;D(http://www.omnimaga.org/Themes/default/images/gpbp_arrow_up.gif)
Note that the downgrade protection is only temporarily removed. If the calculator does reboot before you downgrade, you'll have to run downgradeCX again.
Also, downgradeCX needs Ndless 3.1. It won't be able to save you if you upgrade to OS 3.2 which will block Ndless. But the downgrade source code now publicly exists, and you'll just need to inject it with a flaw, if such a flaw still exists in the next OS...
Download from the TI-Planet news:
http://tiplanet.org/forum/viewtopic.php?p=122163#p122163