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.

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.

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.

Two new variants of the Arduino Uno development board, the lightweight Uno R4 Minima and the full-fledged Uno R4 WiFi, are each powered by a 32-bit microcontroller. These next-generation Uno boards ...

The Uno Rev3, is a great beginner board as it's included in many starter kits. It's also complemented with a host of online resources that even without the official Projects Book from Arduino, you ...

The long-awaited Arduino Due just hit the market, replacing the 8-bit, 16 MHz brain of the popular Uno microcontroller prototyping platform with a 32-bit, 84 MHz processor, while augmenting inputs ...