void penchg (mode) TPLT.C Level 13
int mode When mode = 1, your plotter will stop when a color change is requested, allowing you to change pens. Hitting any key will restart the plotting. 
The default is mode = 0, with automatic pen changing using a multipen plotter and the information in CONFIG.PEN.
penchg() does not exist in GUI versions of GraphiC. You control the behavior of the output device through the printer settings interface.