Or at least, "trying to prevent tampering" and "trying to make regulation authorities believe that we're preventing tampering"... but as a matter of fact, persistently failing at preventing tampering :)

Actually, one of the older versions, OS 3.0.1, released at the beginning of April 2011, _did_ have a number of wrinkles in the math functionality that were not present in 1.x-2.x OS versions :)

Don't you think that this idea has already surfaced over the years, and multiple times at that ? ;)
But the fact remains that no viable "open source calculator" model ever surfaced.

You're partially missing the point ;)
On the one hand, of course, TI is actively trying to block arbitrary native code execution on the platform - and failing at it.
But on the other hand, Lua programming is about using something that TI themselves (silently) put into the OS. And TI broke what we had been using so far, documents made of compressed+encrypted part copied from TI's own documents and a part merely compressed. We're back to a situation where only TI can _easily_ generate Lua documents that OS 3.0.2 understands... until the encryption of all document parts is documented and replicated by third parties...

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" ;-)