The OS that would be put on those old phones, would be a bare minimal, stripped down OS. No need for managing screen, audio, radio/GSM/EDGE/3-4-5G. Not sure ab

The OS that would be put on those old phones, would be a bare minimal, stripped down OS. No need for managing screen, audio, radio/GSM/EDGE/3-4-5G. Not sure about the IO interface, could reuse the USB, but maybe there is some internal (and standard enough) bus to reuse too...