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

The Arduino Uno is an open-source microcontroller board based on the Microchip ATmega328P microcontroller and developed by Arduino.cc. It was first developed back in 2003 as an affordable ...

The Arduino Uno R4 is to have a Renesas RA4M1 32-bit Arm Cortex-M4 microcontroller, and there are "no plans to discontinue the popular Uno R3" , according. About Us; ... Renesas RA4M1 super-set block ...

Arduino has launched its next generation of UNO boards, introducing a 32-bit Renesas microcontroller and Espressif ESP32-S3 module, one-click cloud connectivity and plenty of I/O plus a 12×8 red LED ...