The Arduino Uno-compatible board has an MCS-51 (often called 8051 instead) instead of the usual ATmega328P/ATmega168. Specifically, [ElectroBoy] uses the AT89S52.

T-Display-S3 AMOLED is a display screen module with a 1.91″ diagonal screen, based on our previous S3 module, we have upgraded the screen, resolution and antenna from LCD to AMOLED and the ...