Pimping my Casio with Oddly Specific Objects' alternate motherboard and firmware
What would be the most power-efficient way to get data or code into something like this without having to take the back off or add a port? Maybe a light sensor, like the old Timex watches? https://en.wikipedia.org/wiki/Timex_DatalinkI guess you could do it with a peltier element and the temperature sensor, if you had a lot of time. :)