Hi, I just got a new TI 84 Plus CE and I accidentally updated it to OS 5.6.1 without knowing it was for the US region and not for Asia. I also found out the hard way that OS 5.6.1 is not approved for use and I can't downgrade it. Is there anyway to downgrade to OS 5.6.0 at least?
Hi There, are you saying that 5.6.1 is not approved for use where you are from? (Asia?)

I'm afraid the downgrade tools aren't working for any OS > 5.5 Sad.
Surely there must be a way right? 5.6.1 is not approved for exam use here in Singapore
That's an excellent reason to ask TI for an official way to downgrade to at least 5.6.0... or to make 5.6.1 approved. Regardless they would have to provide you with a solution hmmm.

Could you contact TI-Cares and let us know what they reply?
Besides contacting TI-Cares, you could also attempt to return your new TI-84 Plus CE to the reseller.
Update: I talked to the reseller and reseller says that the calculator cannot be returned and the warranty is void and accidental use is not part of it. However, OS 5.6.1 will be approved for exam use by the end of the year which is good for me. Btw, thanks all for the quick responses. Really appreciate it
Thank you for the update! It's good news to hear that the OS will be accepted eventually, although the end of the year is quite a long ways away. I might suggest talking directly to TI Cares if you need a calculator with the correct OS sooner. That reseller obviously doesn't know what 'accidental use' is. What's the point of a warranty if you can't use the calculator as intended and install official TI software? Rolling Eyes
I thought there was a way to manually edit the minimum OS version. Or does his/her boot code work around that feature in Cermastr?
Sadly no, OS 5.6 fixed all the bootcode hacks, so there's no way to send a lower OS version (at least that I know of). Out of curiosity, what CE revision and bootcode do you have now JK76? You can check the back of the calc for a very faintly carved serial number underneath all the manufacturing data, mine's an L-0419L, or a rev L calc. You can check the bootcode by pressing [mode] + [alpha] + [ln]/[S], and there's some fun self-test stuff you can mess with too. Mine's 5.3.1 and therefore viable for fixing. It might not be possible now, but in the future we may have something to fix it or maybe TI will stop removing some of the only features that make their calcs worth the high prices.
King Dub Dub wrote:
Sadly no, OS 5.6 fixed all the bootcode hacks

Ha. Hahahaha. As if.
MateoConLechuga wrote:
King Dub Dub wrote:
Sadly no, OS 5.6 fixed all the bootcode hacks

Ha. Hahahaha. As if.

I didn't cite my stuff so I guess I can't yell at you for being cryptic again, but from Commandz's BootSwap utility:
BootSwap readme.md wrote:
It also does not run on OS 5.6.1, as TI now properly uses sector protection.

And as for CERMASTR:
TI-Planet Archives wrote:
Not yet compatible with OS 5.5 / 5.6, a new version compatible and with updated features update will be available soon.

I couldn't find anything for why Cauldron won't work, but it's apparently extremely dangerous (or at least more so than BootSwap, which is also better) but in the TheMachine also added another warning to the readme:
Cauldron readme.md wrote:
DO NOT USE. It may induce various fatal error in the toolchain

Not entirely sure what that means, but it's not the best tool to use anyway.

On a somewhat unrelated note, I find it ironic that the lettuce man said this at one point:
MateoConLechuga wrote:
Boot code is basically burned into the flash chip. I don't think anyone has or wants to try to defeat that.

I wish that was still true; now please prove me wrong.
Bootswap/Cauldron use a separate exploit than the one that is used to downgrade. As far as I know, it is extremely easy to find alternative port unlock exploits, which is why Cesium is often updated just days after a new OS release (it uses the same exploit for a different purpose).
Yeah, using Bootswap/Cauldron for bypassing downgrade protection is like using a chainsaw to cut a steak. While technically it will work, you're far less likely to lose an arm if you just stick to a knife. While the chainsaw has its uses, the knife is much better suited for something simple like steak.
To further the analogy (for no good reason (please don't put me on a watchlist)), the TSA is going to be upset if you try to take either onto an airplane, in the same way that TI wants both bootcode exploits and downgrade exploits banned. Like the TSA, TI is also hilariously incompetent at enforcing this, and while it's much easier to keep the chainsaw off of a plane than a dinner knife, they still mostly rely on people fearing the consequences of breaking the rules rather than ensuring they can never be broken in the first place.

As I've stated previously, I won't be publicly releasing or even publicly disclosing whether I've developed an update for BootSwap for 5.6.1+, barring some major change in conditions, such as the CabriJr bug getting broken by an OS update, or on the off chance an updated Cauldron is released. I also won't release any downgrade tools until arTIfiCE gets broken. However, there's so many security holes in the OS it's not even funny, so I'm sure anyone familiar with assembly could write one in an afternoon at the moment. Right now TI seems to be relying on a implicit agreement that the community won't release a downgrade tool in exchange for not breaking the cabriJr exploit, so I doubt anyone else will release one, either.
My boot code is and it is L-08200
Update : Sent TI Cares this email and this is what they replied

Dear customer,

Thank you for writing to Texas Instruments.

We understand that you are enquiring about your calculator's operating system (OS) and we are happy to assist you with your enquiry.

We are sorry that the firmware of the calculator does not allow the OS of the calculator to be downgraded.

You should be able to find OS downgrader tools and programs that are not created by Texas Instruments. These programs can help you downgrade your OS.

However, this is a non-TI approved workaround. Please note that since it involves a non-TI, third party program, your warranty will be void if the method damages your calculator.

Please ensure that you have the TI-Connect CE software installed: https://education.ti.com/en-PH/software/details/en/CA9C74CAD02440A69FDC7189D7E1B6C2/swticonnectcesoftware

Please also download and save your OS file: https://education.ti.com/en-ph/software/details/en/812e5fcf48c6456cb156a03de5d07016/singaporeapprovedosapps

We hope that you find this information helpful. If you have further questions or comments, please feel free to contact us again.

Thank you and have a nice day.
TI wrote:
You should be able to find OS downgrader tools and programs that are not created by Texas Instruments. These programs can help you downgrade your OS.

However, this is a non-TI approved workaround. Please note that since it involves a non-TI, third party program, your warranty will be void if the method damages your calculator.

That whole response is sad and hilarious, but I found this section particularly so. Not only are they unwilling/unable to help with first party tools, but they actually have to recommend jail-breaking the calculator to assist you at all. Too bad the downgrade tools don't work on 5.6.1 so their work-around is useless. Laughing

I'm so sorry you can't downgrade, hopefully the new OS get approved before the end of the year comes around.
Oh boy, here's my interpretation:
me wrote:
We understand that there are valid reasons to downgrade. Unfortunately, we have intentionally prevented you from doing so.
Feel free to jailbreak your calc though... but if you do and something happens, that's on you sweetie.
Anyways, here's a link to an OS that you can't install, kthxbai!
Update: Test board approved all OS Versions till 5.6.0
5.6.1 is not approved yet nor listed on TI's website for Singapore for download
Oh man that sucks dude, but I am sure that the Singapore test board will approve the latest OS version very soon, it is not very different from 5.6.0.
Update: TI Cares is absolutely incomprehensible. Sent an email asking when will OS 5.6.1 be released in Singapore on their website and get the exact same reply as last time. Really losing out hope on OS 5.6.1 coming to Singapore. At this rate, I'll really be happy if my calc can be downgraded to OS 5.6.0 at the very least because it's supported
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