TI-Nspire Hack Enables User Programming

An anonymous reader writes "Texas Instruments' most recent, ARM-based series of graphing calculators, the TI-Nspire line, has long resisted users' efforts to run their own software. (Unlike other TI calculator models, which can be programmed either in BASIC, C, or assembly language, the Nspire only supports an extremely limited form of BASIC.) A bug in the Nspire's OS was recently discovered, however, which can be exploited to execute arbitrary machine code. Now the first version of a tool called Ndless has been released, enabling users, for the first time, to write and run their own C and assembly programs on the device. This opens up exciting new possibilities for these devices, which are extremely powerful compared to TI's other calculator offerings, but (thanks to the built-in software's limitations) have hitherto been largely ignored by the calculator programming community."

Comments

WHY?

[v1]

WHY do they do that? I could see if they had either some expensive dev tool you had to use to make your own powerful apps, or if they were selling a much more expensive calculator that had all the programming options unlocked, but in this case I don't see any profit in it for TI to not let people program them?

Re:WHY?

[fuzzyfuzzyfungus]

Either it is reflexive control freakery or, more likely, it has to do with the demands of standardized testing.

TI's calculator division makes its money(and justifies its margins, I'm not sure that the price of a TI-83 has fallen to anything except inflation since I had to buy one back in secondary school) by being the de-facto standard calculator for education. Sure, a few of the hardcore nerds in engineering still have their HP somethings, and anybody doing real crunching will graduate to a full computer running one of the mathematical packages; but TI is it everywhere else.

The Wikipedia page mentions several features aimed specifically at educational testing: "The TI-Nspire also features a "testing mode" LED indicator, designed to stop potential cheating, informing test supervisors that the calculator is still denying access to saved files and possibly restricting geometry features on the handheld during the test. It also features a timer. At the end of a test, the supervisor is required to check the calculator's timer to see if it has not been removed out of "testing mode"." Essentially, because it is commonly used on tests, the educational customers who drive most of the sales(directly or indirectly, some districts purchase, some mandate, some just encourage) would really like the calculator to be a "trusted" black box capable of doing only what it says on the tin, not doing arbitrary computer tasks(like storing notes, or doing symbolic integration and differentiation when the kids are supposed to be learning that).

If it is possible for people to write their own stuff, in something more than a crippled little scripting language, it becomes possible to subvert these testing controls.

Re:WHY?

[v1]

This shows an interesting sliding window of sorts as to where the cutoff between allowed and not-allowed tools come into mathematics.

Day used to be when we had to look up values in a Log table and be able to find roots by hand etc. Using a calculator for that back then would clearly have been cheating. Nowadays that's exactly why we have the calculators on a test, so we're not bogged down doing grindy math and can get to the task of computing derivatives and solving for x, and that has become the banned feature.

I suppose ten years from now we'll have moved on and be working on more advanced mathematics, having left all of algebra to our calculators on the test...

Re:WHY?

[bhtooefr]

Except that's where a carefully written fake UI program that pretends to wipe the calculator memory when the teacher goes through the menus comes in handy. Special key combo, calc drops into the real UI, and all of your stuff is intact.

(Or, if the calc's an HP 49g+ or 50g, you can just move everything off to an SD or MMC card, pocket the card before going into the class, and after resetting and going to your desk, insert it.)

Re:WHY?

[0100010001010011]

I did this for all my Mechanical Engineering courses. I figured for some tests I would spend upwards of 20 hours programming... It just ended up being my way to study. By time I tested all scenarios, worked out problems by hand to make sure that my equations worked and debugged it some more, I had the equations memorized.

It did save my ass a few times when I made a stupid sign mistake ON the test, but my debugged program gave me the right answer. Went back and double checked my work, and found the sign error.

I also had it print out every step of the solving process so in a pinch (time running out) I could just copy from my calculator screen and get credit for full work.

500 lines of code gets quite tedious after a while on a TI-89 screen.

Re:ti in the past never really supported assembly/

[langelgjm]

What's more, TI actually released assembly programs that would install new features on the calculator. I have a TI-86 from years ago and just recently installed a TI-provided statistics package that gives me the various distributions, test, etc.

Re:TI-Calc love

[Jon Abbott]

Plus there is STILL no good method for entering equations on computers

I recommend LyX, a front-end to latex. When I was in college I was able to take equation-heavy notes real-time in class. My notes usually looked much better than the professor's official class notes as well. LyX does have a learning curve, but you can always remap the keys to whatever you are used to.

Re:What's the point?

[Sir_Lewk]

The thing with the nspires is they are completely worthless. Complete crap, sure they do arithmetic fine, but besides that they do nothing. What this crack does is allow people to program it, without it there wasn't even the possibility of any sort of "homebrew" community for this calculator.

I still don't think you are getting the concept here though. Unlike programming on other platforms, programming on calculators isn't so much a means to an end, it is the end. People don't program them because they want to do fun things with them (though that often is a side effect), they program them because the very act of doing so is fun. The platform provides a very limited set of resources and very tight constraints on things that you want to do, it's this challenge that makes it so popular.

You point at the crappy hardware and say, "Why?". We point at the crappy hardware and say, "That's why."

Square root button

[krischik]

Mine has: http://fx-602p.krischik.com/index.php/Simulator/SymbianOS