SainSmart Melzi Reprap 3D Printer controller board, ATMEGA1284p, A4988 for Arduino The main chip is ATmega1284P (TWICE the memory of the inferior 644P!) Integrated USB chip FT232RL socket Integrated X/Y/Z/E step motor driver with sockets Integrated X/Y/Z stopping with sockets Integrated heatbead temperature controller with sockets