This board is fully compatible with the Arduino Mega 2560 R3.
Because it has 54 digital I/O pins, I use it in several videos as a way to monitor a large number of digital signals when explaining and troubleshooting my 6502-based computer project. If you really want to follow along step-by-step with that project, you may want one of these.
From the manufacturer:
Mega 2560 R3 is a microcontroller board based on the ATmega-16AU, fully compatible with ARDUINO MEGA 2560 REV3.
It has 54 digital input/output pins (of which 15 can be used as PWM outputs), 16 analog inputs, 4 UARTs (hardware serial ports), a 16 MHz crystal oscillator, a USB connection, a power jack, 2 ICSP headers, and a reset button.
It contains everything needed to support the microcontroller. With its bootloader, program can be downloaded directly with USB and you don’t need to use other external programmer.
Just simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started.
The Mega 2560 board is compatible with most shields designed for the Uno.
The 2560 R3 differs from all preceding boards in that it does not use the FTDI USB-to-serial driver chip. Instead, it features the Atmega16U2 programmed as a USB-to-serial converter.
The MEGA 2560 is designed for more complex projects. With 54 digital I/O pins, 16 analog inputs and a larger space for your sketch, it is the recommended board for 3D printers and robotics projects. This gives your projects plenty of room and opportunities.