Aimed at the 8-bit AVR ATmega168 with its mere 16kB of flash and 1kB of SRAM, the diminutive chip can still perform more than well enough to host the rudimentary OS — up to four application ...

He’s not using PWM because frame buffering is not feasible for the 1k SRAM limit of the ATmega168 he used. Instead, shift registers drive the lights which can be mixed to achieve eight different ...