As someone who is rather distrustful of the real motives of the security in general, TOTP is IMHO a good solution that increases security for the user but is also entirely under the user's control.
As this article shows, a 6502-level CPU is definitely powerful enough to do this and other crypto primitives; smartcards, which can perform RSA operations, are roughly of the same power.
As this article shows, a 6502-level CPU is definitely powerful enough to do this and other crypto primitives; smartcards, which can perform RSA operations, are roughly of the same power.