PCB is an interactive printed circuit board editor for the X11 window 
system.  PCB includes a rats nest feature, design rule checking, and 
can provide industry standard RS-274-X (Gerber), NC drill, and centroid 
data (X-Y data) output for use in the board fabrication and assembly 
process.  PCB offers high end features such as an autorouter and trace 
optimizer which can tremendously reduce layout time. 
