TI-Nspire CM calculators sold in China and TI-Nspire CX have almost the same software capabilities.
The only disprency between those is to be able to install a bilingual dictionnary for TI-Nspire CX and not for TI-Nspire CM.
A TI-Nspire CM to TI-Nspire CX transformation or the reverse would give no interest, that's why we didn't look forward about that.
But our chinese friends of
cnCalc.org were struggling since one week to do this transformation.
What are their motivations ?
Nlaunch, the OS launcher for TI-Nspire, is available for monochrome TI-Nspire and TI-Nspire CX, but not yet for TI-Nspire CM because it is based on a Boot2 1.4 exploit
(for monochrome TI-Nspire) and Boot2 3.1 exploit
(for TI-Nspire CX) and the TI-Nspire CM uses a different Boot2.
But once a TI-Nspire CM has been modded into a TI-Nspire CX, it is theoretical to install Nlaunch CX and so :
- launch a Linux OS
- launch a TI-Nspire CX CAS OS
Lets recall how the different software modules
(Boot2, OS) checks the calculator model where they run.
One the one hand, the NAND chip contains the model id at offset 0x804:
- 0x0C for TI-Nspire CAS but also TI-Nspire CAS+
- 0x0D for TI-Nspire Lab Cradle
- 0x0E for TI-Nspire
- 0x0F for TI-Nspire CX CAS
- 0x10 for TI-Nspire CX
- 0x11 for TI-Nspire CM CAS
- 0x12 for TI-Nspire CM
You may think it would be enough to modify this value, but a second value is stored in the ASIC chip:
- 0b00000 for TI-Nspire and TI-Nspire CX
- 0b00001 for TI-Nspire CAS and TI-Nspire CX CAS
- 0b00010 for TI-Nspire CM
- 0b00011 for TI-Nspire CM CAS
- 0b11111 for prototypes TI-Nspire DVT and TI-Nspire CAS DVT
And unlike the NAND chip, we are unable to rewrite the ASIC chip.
When the Boot2 and TI-Nspire OS launch or install an OS, they check if the latter is consistant to these two values:
- model id on NAND memory
- model type of ASIC chip
Take note that the special code 0b11111 found on TI-Nspire DVT prototypes is a debug code that doesn't state the calculator type, and thus disables this second check. That's why we could transform very easily TI-Nspire prototypes to TI-Nspire CAS by rewriting NAND chip.Changing the model id written in the NAND memory incoherently with the a ASIC chip, is no less than a
permanent brick of the calculator.
Indeed, whatever OS used after this modification, one of the two checkings written above would obviously fail and the OS sent will be rejected and/or deleted.
You end up with a OS-less calculator on which you wouldn't be able
anymore to install any OS.
Well, nbzwt, member of the chinese communauty
cnCalc.org has his hand on fire and effectively made a destruction of his TI-Nspire CM calculator:
- by changing his model identification to TI-Nspire CX thanks to a modified nsNandMgr (the only version I support has a security check forbidding this 'destruction')
- by flashing the TI-Nspire CX 3.1 Boot2
His calculator was now unable to approve the installation or the launching of any CX or CM OS.
But then what was the reason for? No, nbzwt isn't crazy - per contra he showed an extraordinary malice.
Now that his calculator is using 3.1 CX Boot2, he is theoretically able to install the Nlaunch OS launcher, which then allows to install and launch any TI-Nspire CX, CM, and even CAS OSes!
A small breakdown had to be known: TI-Nspire CM calculators have only 32 MB of SDRAM memory instead of 64 MB like on the TI-Nspire CX calculators, and official Nlaunch don't work.
But nbzwt released an
Nlaunch fork that works with the TI-Nspire CX 3.1 Boot2 on TI-Nspire CM hardware. :bj:
Let's all congratulate awesome nbzwt loudly for this huge achievement!
Please take note however that I do not invite you to do this modification based on a bricking of the calculator. If for any reason Nlaunch cannot be installed/run (for instance like when future 3.2.4/3.6 OSes will try to fore the Boot2 3.2.4.7 update), the bricking will become permanent.
That's why in the actual forecast, I won't change the security policies of nsMandMgr to allow this transformation.
Source:http://tiplanet.org/forum/gallery/image_page.php?image_id=1307Edit: And precisely, it seems that nbwzt had unfortunately completed the bricking of his TI-Nspire CM bricking by fulfilling complementary tests for the tutorial 
Boot Loader Stage 1 (3.00.99)
Build: 2010/9/9, 17:29:13
Copyright (c) 2006-2010 Texas Instruments Incorporated
Using production keys
Last boot progress: 65
Available system memory: 33196
Checking for NAND: NAND Flash ID: MICRON
SDRAM size: 64 MB
External Power Detected: VBUS.
SDRAM memory test: FAIL TI_B1_ADDRESS_1
BOOT1 Error: Stubbornly refusing to boot due to memory failure.The Boot1 seeks here for the 64 MB RAM of the TI-Nspire CX, which aren't found because we are on a TI-Nspire CM with only 32 MB RAM.
This issue will not happen if you follow carefully, exactly and in order the linked tutorial.
If you want to share this with nbzwt some encouragement words or to send him a share so he can keep developping us other extraordinary tutorials or tools, do not hesitate: nbzwt @ live.cn
