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

To build this project, all you need is three main components: an Arduino Uno, a 16x2 LCD, and a push button. You can connect everything to a breadboard to keep it simple.

The Arduino Nano and Uno are equipped with very similar processors (the chip that essentially serves as the brain of the board). The Nano features an ATmega328, while the Uno sports an ATmega328P.

Arduino says these additions allow for more advanced projects. Besides Wi-Fi and Bluetooth, the UNO R4 Wi-Fi has a built-in LED matrix with 96 dots arranged 12x8.

The Arduino UNO R4 Minima and the Arduino UNO R4 WiFi. But apart from the obvious wireless connectivity hinted by the name what other differences do the microcontrollers have.

The Arduino UNO R4 boasts a 3x performance increase over the UNO R3 and , in addition, SRAM has been upgraded from 2kB to 32kB, and flash memory from 32kB to 256kB to support more complex projects.