This is an Original Arduino Mega board from Arduino Officials based on ATmega16U2.  The Official Arduino Mega 2560 is a Rev3 development board based on the ATmega2560 microcontroller. The board has 54 digital input/output pins (of which 14 can be used as PWM outputs), 16 analog inputs, 4 UARTs (hardware serial ports), a 16MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller, simply connect it to a computer with a USB cable or power it with an AC to DC adaptor or battery to get started.

The Mega is compatible with most shields designed for the Arduino Uno, Duemilanove, or Diecimila. The Arduino Mega can be powered via a USB connection or with an external power supply. The power source is selected automatically. The Arduino Mega2560 has a number of facilities for communicating with a computer, another Arduino, or other microcontrollers.

Revision 2 of the Original Arduino Mega 2560 board has a resistor pulling the 8U2 HWB line to the ground, making it easier to put into DFU mode.

1. ATmega16U2 instead 8U2 as USB to serial converter
2. 1.0 pinout
3. Stronger RESET circuit
4. 5V operating voltage
5. Input voltage (recommended) range from 7V to 12V
6. Input voltage (limit) range from 6V to 20V
7. 40mA DC current per I/O pin
8. 256KB flash memory of which 8KB used by the bootloader
9. 8KB SRAM
10. 4KB EEPROM