Just a hint: In CHIP-8, the timers are expected to decrement at typically 60Hz but in sync with the screen update at the same rate, not sometime mid-frame. Not crazy important for old VIP one but modern variants rely on it as games use it to reduce flicker.

Thank you for supporting CHIP-8 with a tutorial. It’s always nice to see new ones. One tiny nitpick: The code for Dxyn has (still) a collision issue, as the flag variable is initialized with VF instead of 0. If no collision takes place, 0 and not the previous value of VF should be returned in VF.

He explained and showed a nice setup with a live demo for an open loop testing named approach using robot framework and pin testing via connected probes in a testbed for the microcontroller board.