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. Today, 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 builtin software's limitations) have hitherto been largely ignored by the calculator programming community.