This clinic is an introduction to the Computer Automated Traffic System (CATS). CATS is open source software built upon JMRI for creating and operating a modern looking CTC panel. The clinic will open with creating a CTC panel for John Armstrong's "minimum-size loop-to-loop" layout, and operated as a magnet board. It will progress to demonstrating how to add occupancy detection, turnout feedback, turnout control, and signal control, in a simulation mode. The clinic will demonstrate other features built into CATS, including train tracking, session recording, train status display, crew management, and rapid CTC panel development for module groups. For a preview, see the August 2010 NMRA Magazine or http://home.comcast.net/~kb0oys.