Olin, since you've written the code to calculate the dimming table, could you please enhance it to toggle some PC Com port output line - DTR or RTS according to this table. "Port" instruction in Pascal, if I recall correctly. Anybody can connect the LED with resistor and diode to one of these lines. Mike. -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu