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本帖最后由 critor 于 2013-8-27 08:00 编辑
For years, the TI-Nspire community has been working for the openness of the TI-Nspire, in order for its users to operate their calculators to their fullest potential.
And so was born Ndless, a framework for running assembly programs taking full control of the hardware in particular of the processor.
Some examples of Ndless compatible programs:
- the nDoom 3D FPS game, a port of the Doom/Doom2 and compatible computer games
- the Nintendo NES emulator
- the Nintendo Game Boy Color emulator
- the Nintendo Game Boy Advance emulator
- the mViewer image reader
Ndless has existed in several versions, each one specific to a single or a small set of TI-Nspire systems:
| Ndless version | TI-Nspire system version | | 1.0/1.1 | 1.1 | | 1.1 prototype | 1.1 (non-CAS prototypes) | | 1.2 prototype | 1.2 (CAS prototypes) | | 1.3 | 1.3 | | 1.4 | 1.4 | | 1.7 | 1.7 | | 2.0 | 1.7, 2.0.1, 2.1.0 | | 3.1 | 3.1 |
The lack of an Ndless cross version is due to the fact that Ndless is not an officially supported program, and Texas Instruments has actively fought it since system 2.1.
Indeed, Ndless installation exploits some flaws in the TI-Nspire system. But any vulnerability exploited then quickly fixed or blocked by Texas Instruments in the next version of the system, forcing Ndless to always use new vulnerabilities.
Do you think you just don't have to update?
Except that Texas Instruments forces the update through various automated popups.
And eventually, all new TI-Nspire will come preloaded with the latest system - it is therefore not a solution for new users.
You'll tell me you just have to reinstall an earlier version of the system?
This was indeed possible until July 2010. At that date, the last 2.1 system has activated a protection which was there but disabled since the beginning, something we called the "system anti-downgrade protection".
System 2.1 and all subsequent systems are updating a minimal installable version number in a memory area not accessible to users and non clearable by any official menu.
Any previous version of the system is then rejected.
As a solution to those problems, the community did release another little tool, Nlaunch.
The TI-Nspire starts by running three pieces of software:
- Boot Code 1
- Boot Code 2
- operating system
So in order to get to the operating system, there are two safety barriers to be overcome.
Where Ndless did only exploit flaws od the system, Nlaunch goes further as directly addressing the Boot Code 2 and overcoming one of both security barriers.
But as Ndless, Nlaunch is also specific to certain versions of the Boot2:
| Nlaunch version | TI-Nspire Boot2 version | | Nlaunch | 1.4 | | Nlaunch CX | 3.1 (TI-Nspire CX) |
Nlaunch is able to install and run operating systems completely ignoring the minimum version of the system, and even to make a recent system to coexist with an old Ndless compatible system.
Like with operating systems, Texas Instruments quickly responded by including a TI-Nspire CX Boot2 update in its latest 3.2.4 operating system.
The TI-Nspire community wasn't worried about that:
- current TI-Nspire users should simply be careful not to update their Boot2 when updating their system, thanks to the small TNOC tool
- in case of omission of this manipulation, it was still possible to reprogram the older Boot2 version using an inexpensive TTL/USB interface (RS232)
- and owners of new TI-Nspire CX could also apply this last solution
This was without counting on the wickedness of the Texas Instruments development team...
We could confirm that when updating a current TI-Nspire CX to the new 3.2.4 Boot2, it was still possible to reinstall the old Nlaunch compatible 3.1 Boot2.
But we hadn't tested this on new TI-Nspire CX coming preloaded with versions 3.2.4 of the system and the Boot2 ...
And although Boot2 3.1 is flashed successfuly through RS232 on these units, it is simply unable to run properly! {:thumbdown:}
The boot2 fails on a non-recoverable error (System Error) and the RS232 console tells us a little more with the "BOOT2 Error: posix_file_init() error".
It's an error that has to do with the file system. But it's obviously still intact, as when flashing back the original 3.2.4 Boot2 the TI-Nspire CX boots successfuly.
So, Texas Instruments did probably change something on the new TI-Nspire CX, something that is managed properly by the new 3.2.4 Boot2 but not the old 3.1 Boot2.
Up to date, we do not know exactly what it is
So basically, Texas Instruments just invented us a new antidowngrade protection, "Boot2 antidowngrade protection". But managing to make its own older version of the code crash instead of giving you a clear and related error message is not very clean from my point of view - it just looks like a dirty hack - we were used to much cleaner protections so far...
In conclusion, the new TI-Nspire CX sold from now on are completely closed, with no known way to install Ndless or Nlaunch up to date. {:thumbdown:}
If you want to use Ndless or Nlaunch, we'd advise you to give up on purchasing a brand new TI-Nspire CX and to look for it on the second-hand market.
In fact on the back of the TI-Nspire CX, on the right of the serial number, is what is called the datestamp, a 7-character code.
The new TI-Nspire CX crashing Boot2 3.1 which have been reported to us up to date have the datestamp 'P-0313J'.
This means that they were manufactured in the TI factory code P (China) in March 2013, and that they include the hardware revision J (11th version) of the motherboard.
On the second hand market you'll be able to ask the seller the datestamp of the calculator, and to buy only TI-Nspire CX whose datestamp ends with a letter from A to I.
This is a sad day for the community. For the third time, Ndless and all its compatible programs have been beaten to death, and even stronger than the previous times. Will they be able to survive this time? ... :'(
Source:
http://tiplanet.org/forum/viewtopic.php?p=147130&lang=en
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发表于 2013-8-27 00:36:20
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发表于 2013-8-30 18:06:02