What happens if I somehow manage to install older OS on Y HW

→ **MyCalcs** profile · by **SuperXX** » 15 May 2021, 10:35

I was searching on how could I downgrade my revision Y calculator from OS 4.2 to OS 3.6, but it seems that my calculator doesn't get lower then that and nasgmr doesn't allow me to do that neither.
So I was wondering, what really happens if a system lower then then the supported by the hardware revision would do. Why it can't be done? Does the hardware really change a lot from a older revision to the Y revision?

Thank You

→ **MyCalcs** profile · by **critor** » 15 May 2021, 10:45

nsNandMgr (or its successor BtMg) should work.
You need to send the older OS immediately after patching the minOS version. If the calculator does reboot in the meantime, the minOS version is going to be set again.

I don't remember trying it, but OS versions 4.0.0 and lower should be able to run on hardware revision W+, but with an incorrect and unreadable display. So pretty useless.

→ **MyCalcs** profile · by **SuperXX** » 15 May 2021, 14:57

So. If I update the calculator to a newer version, like OS 4.4 and then remove the minOS protection and then instead of downgrading the calculator with the .tcc file to OS 4.2, I can just install 3.6 and it should work? And if something goes wrong can I just go to the mantaince menu, uninstall the OS and the install the 4.2 version it should go back to normal?

→ **MyCalcs** profile · by **Ti64CLi++** » 15 May 2021, 14:59

Yes you should be able to do exactly that

→ **MyCalcs** profile · by **critor** » 15 May 2021, 15:04

SuperXX wrote:So. If I update the calculator to a newer version, like OS 4.4 and then remove the minOS protection and then instead of downgrading the calculator with the .tcc file to OS 4.2, I can just install 3.6 and it should work?

Sorry if I haven't been clear enough.

OS versions 4.0.0 and below don't support the hardware revision W+ newer screen, there is no way it's going to work.

3.6 OS is going to be totally unusable once installed on your calculator.

→ **MyCalcs** profile · by **Ti64CLi++** » 15 May 2021, 15:06

critor wrote:3.6 OS is going to be totally unusable once installed on your calculator.

Yes sorry that's what I meant. It won't be usable, but you should be able to try, out of curiosity for example

→ **MyCalcs** profile · by **SuperXX** » 15 May 2021, 15:23

critor wrote:
SuperXX wrote:So. If I update the calculator to a newer version, like OS 4.4 and then remove the minOS protection and then instead of downgrading the calculator with the .tcc file to OS 4.2, I can just install 3.6 and it should work?

Sorry if I haven't been clear enough.

OS versions 4.0.0 and below don't support the hardware revision W+ newer screen, there is no way it's going to work.

3.6 OS is going to be totally unusable once installed on your calculator.

Ok ok. Probably I won't do it, but it's great to know it. Thank You

→ **MyCalcs** profile · by **SuperXX** » 16 May 2021, 13:31

So, I actually tried doing it and for the ones who are wondering what happened, here I have a picture:

It just crashes with this screen, after the loading bar reaches 100%

Just go to the maintance menu, delete the OS and install a compatible one, because it wasn´t usable at all.

Maybe one day someone can port it or something like that