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Author Topic: 84+/SE Boot Pages Modified  (Read 39430 times)

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Offline Munchor

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84+/SE Boot Pages Modified
« on: June 27, 2011, 06:34:13 am »
Yesterday, Brandon Wilson tweeted that he had managed to modify both boot pages in the 84+/SE, through software only, as you can see in the following picture:



Another tweet from Brandon Wilson tells us about some of the possibilities that this will bring:

Quote from: Brandon Wilson
It means we can modify the boot code & completely strip out all TI copyrighted code from the device. No more exploits or hacks.

From now on, if TI tries any more "tricks" to block features or downgrades, they can now be easily fixed thanks to this.

Some may say this is a fail from TI and others might say it is the end of all the problems caused by TI blocking downgrades and other features. I question, though, can't TI change the boot pages in a newer OS? Either way, I think this is wonderful news.

Finally I have to add that thepenguin77 also discovered this, but separately from Brandon Wilson.

Below is the most recent tweet by Brandon Wilson concerning this program:

Quote from: Brandon Wilson
Boot code one is a simple program. Pocket exploit...probably best not to say yet. But very simple & easy to use.
« Last Edit: June 27, 2011, 08:34:34 am by ephan »
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Offline JosJuice

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Re: 84+/SE Boot Pages Modified
« Reply #1 on: June 27, 2011, 06:37:45 am »
Quote from: ephan on June 27, 2011, 06:34:13 am
I question, though, can't TI change the boot pages in a newer OS?
At first, we all thought that the boot pages couldn't be written to, so I think it's safe to assume that TI doesn't know how to do it. And even if they do change them, we can probably just change them back...
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Offline TIfanx1999

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Re: 84+/SE Boot Pages Modified
« Reply #2 on: June 27, 2011, 08:28:18 am »
Oh my! :O Does this mean that the new TI-84 pocket can be modded to accept OS downgrades/custom Oses? If so, that would be great news indeed!
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Offline fb39ca4

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Re: 84+/SE Boot Pages Modified
« Reply #3 on: June 27, 2011, 09:25:16 am »
Great news!
Does the 84 pocket have different signing keys than the original? Is that why we can't use custom OSes ATM?
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Offline thepenguin77

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Re: 84+/SE Boot Pages Modified
« Reply #4 on: June 27, 2011, 09:28:31 am »
Well, I've talked to brandonW about this. We really don't want to use this to make the pocket able to accept other OS's. The problem comes from how dangerous this is. In the end, it really is just like any flash mod, but the thing is, if something goes wrong while the boot code is all FF's, instant, permanent brick. Unless you can wire up the flash chip and reprogram it, your calculator is done. It will execute one instruction and end.

If we did make a boot code modder, of course it would be extremely safe. It would check batteries all over the place and probably would be stepped through instruction by instruction several times. But, boot code 1.03 will probably be coming to america soon which means it will become more widespread. And if we release this as the only way to install other OS's, over time, there will probably be about 5 people using it every day. If just 1 person is an idiot and tricks their calculator into running it with low batteries, they will brick their calculator and we will be in a huge mess online.

Besides, we don't even need to do this. BrandonW and I have come up with different ways to beat the boot code, and my program to do it is already done. With two exploits, we should be covered for a long time unless TI looks through their boot code for errors, which they won't.

Edit:
    Now that I think about it, NOPing out some checks in the boot code wouldn't really be that dangerous. (I've already NOPed stuff in my boot code.) So I guess a mod like this could be a possibility, but only if we need to do it.
« Last Edit: June 27, 2011, 09:46:36 am by thepenguin77 »
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Re: 84+/SE Boot Pages Modified
« Reply #5 on: June 27, 2011, 09:34:43 am »
Quote
Does the 84 pocket have different signing keys than the original?
Maybe they have _additional_ keys (I don't know), but the 84+ Pocket does support the old signing key: an unmodified OS 2.55MP for regular 84+(SE) can be successfully sent to a 84+ Pocket :)
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Offline thepenguin77

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Re: 84+/SE Boot Pages Modified
« Reply #6 on: June 27, 2011, 09:50:00 am »
It's been a while, so I'll give you a hint: The 258 bytes at the start of page 73h are a new signature that the boot code expects to be present.
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Offline TIfanx1999

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Re: 84+/SE Boot Pages Modified
« Reply #7 on: June 27, 2011, 09:55:28 am »
Quote from: thepenguin77 on June 27, 2011, 09:28:31 am
Well, I've talked to brandonW about this. We really don't want to use this to make the pocket able to accept other OS's. The problem comes from how dangerous this is. In the end, it really is just like any flash mod, but the thing is, if something goes wrong while the boot code is all FF's, instant, permanent brick. Unless you can wire up the flash chip and reprogram it, your calculator is done. It will execute one instruction and end.

If we did make a boot code modder, of course it would be extremely safe. It would check batteries all over the place and probably would be stepped through instruction by instruction several times. But, boot code 1.03 will probably be coming to america soon which means it will become more widespread. And if we release this as the only way to install other OS's, over time, there will probably be about 5 people using it every day. If just 1 person is an idiot and tricks their calculator into running it with low batteries, they will brick their calculator and we will be in a huge mess online.

Besides, we don't even need to do this. BrandonW and I have come up with different ways to beat the boot code, and my program to do it is already done. With two exploits, we should be covered for a long time unless TI looks through their boot code for errors, which they won't.

Edit:
    Now that I think about it, NOPing out some checks in the boot code wouldn't really be that dangerous. (I've already NOPed stuff in my boot code.) So I guess a mod like this could be a possibility, but only if we need to do it.

This is great news! I'm glad that there is a safer way instead. Regardless of what OS it was running, I was planning to get a TI-84 pocket when it is released. It makes me even happier that I will be able to run whatever OS I choose though. ;D Awesome work thepenguin and Brandon W.! You guys kick so much ass!
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Offline aeTIos

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Re: 84+/SE Boot Pages Modified
« Reply #8 on: June 27, 2011, 10:01:10 am »
hooray! BrandonW's CalcGod factor: >9000! :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup:
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Offline ruler501

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Re: 84+/SE Boot Pages Modified
« Reply #9 on: June 27, 2011, 10:52:18 am »
The only word I can think of to describe this is wow. I love how we now have complete control over the 84. Hopefully we will also be able to do this to other calcs eventually
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Re: 84+/SE Boot Pages Modified
« Reply #10 on: June 27, 2011, 12:52:26 pm »
Thank you TI for all those weird holes you seem to leave everywhere :thumbsup:
« Last Edit: June 27, 2011, 12:52:34 pm by Deep Thought »
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Offline ruler501

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Re: 84+/SE Boot Pages Modified
« Reply #11 on: June 27, 2011, 12:57:55 pm »
Quote from: Deep Thought on June 27, 2011, 12:52:26 pm
Thank you TI for all those weird holes you seem to leave everywhere ;D
Thank god for TI's bad programming
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Re: 84+/SE Boot Pages Modified
« Reply #12 on: June 27, 2011, 01:03:38 pm »
Well that's nice. Can't wait to see this on the other 83+ calcs. And that would allow for custom boot code?
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Offline ruler501

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Re: 84+/SE Boot Pages Modified
« Reply #13 on: June 27, 2011, 01:08:18 pm »
I think from what they said that this allows anything you could possibly do. The hardware is completely open now
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Re: 84+/SE Boot Pages Modified
« Reply #14 on: June 27, 2011, 01:09:58 pm »
So we can boot Windows Vista now! :D
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« Last Edit: June 27, 2011, 01:10:13 pm by Deep Thought »
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