TI Bans all Assembly Programming, Casio Limits Add-ins. Please don't follow suit HP.

[debrouxl]

Well, basically, no device (not just graphing calculators) is ever bug-free
Even software developed using formal methods - which is far more difficult and costly, to the point that it can only be done for code bases much smaller than giac is - is subject to bugs in the specification, the formal validation code, and/or of course the underlying hardware. seL4's proofs assume that the processor registers, the MMU and various other hardware parts are working according to the published specification. Then there are the side channels, vulnerabilities related to speculative execution, etc.