I did actually read the bit you're quoting. But I'm not really (truly, totally or fully, if you prefer) convinced by it: it's a thought exercise. Until such an event happens, it's a probability that it does not happen, see ? ;-)

Every problem, no matter how complicated, has a solution that is trivially stated... and wrong (impractical, etc.).

Remember, they're the leader on that market. Many school mandate the usage of TI calcs...

As written in the grandparent of your post, everything in the Nspire is signed. The first-stage boot1 is not rewritable; the second-stage boot is signed and checked by the boot1; the OS is signed and checked by the boot2.
Signature is done through 1024-bit RSA public keys, we can easily extract all of these keys... but it's not practical to factor them: three-four orders of magnitude more difficult than the state of the art (currently approximately 768 bits), which is itself three-four orders of magnitude more difficult than the 512-bit RSA keys of TI-Z80 and TI-68k calcs that we factored last year.

Therefore, we can't just "destroy the firmware check absolutely" off-line, we have to do it on-calc... and doing so requires exploiting the OS... and finding reliable exploits requires reverse-engineering, fuzzing, etc.

Please RTFA: TI is doing much more than just preventing us from mirroring their software (which they don't bother doing themselves) ;-)

> How does people running their own programs hurt TI?
Agreed, it helps them selling more calculators (because TI-Z80 and TI-68k moddable calculators are more desirable to users than a number of other little programmable models).

> TI does not sell apps do they?
They did, many years ago. But they stopped doing so.

> If anything it's the Ndless community that's being counterproductive here.
I wouldn't call making calculators more useful to users (it's not just about games - see, on TI-68k calculators, lower-level access to the OS does enable us to do more powerful functionality and do it faster) "counterproductive" ;-)

Exactly, mod parent up.
While we can (and do) build our own OS for TI-Z80 and TI-68k calculators, especially since we factored the RSA public keys used for signature (but before that on both series, in a more hack-ish way), TI has taken significant extra effort for preventing us from doing the same on Nspire calculators. Multiple layers of signature with 1024-bit RSA keys, to begin with.

And we're already working on reverse-engineering OS 2.1 ;)

> amajor part of TI's calculator business is created by the un-hackability of their calculators.
On the contrary: it's a fact that their past calculator lines, TI-Z80 and TI-68k, are _very_ hackable. Yet they sold millions of them (and it's precisely their hackability - games - that makes them more desirable for users than a number of other calculator models) !

People deciding the blunder of banning TI calculators from education would be _severely_ incompetent:
* an unfixable exploit which enables hack-ish installation of arbitrarily modified OS on TI-68k calculators has been known for 11 years... but it did not get TI calculators banned from standardized tests for that very reason.

* the factorization of all interesting 512-bit RSA public keys used for signature of OS and FlashApps, and therefore the seamless installation of arbitrarily modified OS (resigned with the deduced private keys) on TI-Z80 and TI-68k calculators, was made in 2009... but again, it did not get TI calculators banned from standardized tests for that very reason.
Nowadays, we're even fixing TI's bugs for them (there's an unofficial patch for the terribly unstable OS 2.53 MP for 84+ - the bugfix was reported months ago to TI, but they still don't provide it to users).

I'm not really convinced that too much functionality would hurt sales - but it's a fact that the lackluster functionality of Nspire calculators, prior to Ndless, _did_ hurt sales ;-)
It's pretty easy to understand why: Nspires are expensive, and users don't get much for their money. The first version of the OS didn't even contain any form of BASIC programming (!!), and that four years later, the BASIC of Nspires remains sub-par compared to the TI-Z80 and TI-68k BASIC.

As for TI calculators being banned from education... people deciding such a blunder would be _severely_ incompetent:
* an unfixable exploit which enables hack-ish installation of arbitrarily modified OS on TI-68k calculators has been known for 11 years... but it did not get TI calculators banned from standardized tests for that very reason.

* the factorization of all interesting 512-bit RSA public keys used for signature of OS and FlashApps, and therefore the seamless installation of arbitrarily modified OS (resigned with the deduced private keys) on TI-Z80 and TI-68k calculators, was made in 2009... but again, it did not get TI calculators banned from standardized tests for that very reason.
Nowadays, we're even fixing TI's bugs for them (there's an unofficial patch for the terribly unstable OS 2.53 MP for 84+).