Not a problem.


Here's an animated GIF I've posted here in july when we discovered all this.
You can see all SD/Flash related menus and screens.

Of course, everything is failing...




Seems the diagnostic software can even update itself, by looking for its replacement code on the external SD card...

So it can flash everything:
- NAND ROM (boot1)
- NOR ROM (boot2 + diagnostic + OS)

- NOR ROM (boot1)
- NAND ROM (boot2 + diagnostic + OS)

Quote from: critor on December 26, 2010, 06:34:41 pm

- NAND ROM (boot1)
- NOR ROM (boot2 + diagnostic + OS)

I think it's the other way around.

Edited. Thank you calc84maniac.

Boot1 immediately runs when the calc turns on, however, the nor rom cannot be very big, so boot2 handles decrypting the os.

And the boot1 rom can't be erased, or can it?

According to some diagnostic strings quoted above, it seems that it is possible for the diagnostic software to reprogram the boot1.

Quote from: critor on December 26, 2010, 09:30:19 pm

Quote from: graphmastur on December 26, 2010, 09:23:44 pm

And the boot1 rom can't be erased, or can it?

According to some diagnostic strings quoted above, it seems that it is possible for the diagnostic software to reprogram the boot1.

Excellent! Is boot1 checked at all for encryption or signatures?

I said it *seems*.
The diagnostic sofware is doing something with the NOR ROM (boot1).

I don't think that boot1 is being checked, but this would be a very dangerous way.
With a faulty boot1, your Nspire won't boot anymore... And this cannot be fixed.


We're currently not even able to correctly write a diagnostic software. Along with his "diagsdumper", ExtendeD made me beta-test a "diagswriter".
Tried on 2 calculators, success rate is 50%.
It worked perfectly on one calculator...
On the other one, whatever I did, the diagnostic software was not written correctly. The 2nd half of the written code was correct, but the 1st half was just crap.

There may be some kind of protection. Some memory pages might be write-protected, although it's strange it's worked once (and on a TouchPad - not an old calculator).

But writing a new diagnostic software is not dangerous. The Nspire can still boot without a diagnostic software.
Until we understand why, and find a way to make it work in all cases, I wouldn't try to write boot1/boot2 if I were you.

I was thinking of a boot2writer - so you can change boot2 1.4 to 1.1
I can test this on the emulator with the /1=boot1.raw , to see
if boot1 complains about a corrupted boot2.
Am I on the right path if I use the write_nand_page call?