MaxCoderz

Is it possible to replace Ti-OS with something else? Not that'd it'd be particularly useful, but it'd certainly be interesting. My guess is that it's stored in ROM somewhere, which could be difficult to access. On the other hand, Ti does update the OS, so it's may be possible. Any thoughts?

Yes, you can send unsigned operating systems to the TI calculator (not that I'd especially recommend it at the moment - there aren't any serious replacement operating systems out there).