This is the August 12, 2009 Adafruit Motor shield firmware with basic Microstepping support. Works with all Arduinos and the Mega Updated in September 2012 for use on PIC32 architecture (chipKIT/MPIDE) For more information on the shield, please visit http://www.ladyada.net/make/mshield/ To install, click DOWNLOAD SOURCE in the top right corner, and see our tutorial at http://www.ladyada.net/library/arduino/libraries.html on Arduino Library installation