MPLAB X is an Integrated Development Environment (IDE) for writing and debugging applications for Microchip's microcontrollers and digital signal controllers. If building on a 64-bit Slackware, you will need 32-bit compatibility libraries. See the Microchip wiki for required files: http://microchip.wikidot.com/install:mplabx-lin64 Alternately, simply follow Eric Hameleers' multilib guide: http://alien.slackbook.org/dokuwiki/doku.php?id=slackware:multilib His provided packages satisfy all MPLAB X library requirements.