Introduction :
RepRap UNO Meg Shield, or RAMPS for short. It is designed to fit the entire electronics needed for a RepRap in one small package for low cost. RAMPS interfaces an UNO Mega with the powerful UNO MEGA platform and has plenty room for expansion. The modular design includes plug in stepper drivers and extruder control electronics on an UNO MEGA shield for easy service, part replacement, upgrade-ability and expansion. Additionally, a number of UNO expansion boards can be added to the system as long as the main RAMPS board is kept to the top of the stack.Version 1.4 uses surface mount capacitors and resistors to further cover edge issue cases.

How to use it
It is relatively simple to wire up the RAMPS. Just add the extruder heating coil wire to D10, the thermistor to the two T0 pins on middle right right, and wire up the steppers and endstops. From left to right, wire all of the stepper motor's wires as red, blue, green, and black or red, green, yellow, blue into the pins next to the Pololus. When you connect the wires to the endstops (if you are using 3 endstops, plug them into the MIN (-) slots), make sure you match the labels.