Hello, So if I am not wrong then the following is a list between what pins on the 18 pin pic16f84 correspond to the 508/509: =========================================== ====================== F84 | 508/509 | VDD (5V Pulse) 14 | 1 | VPP (13V Pulse) 4 | 4 | <- MCLR* RB7 13 | 7 | RB6 12 | 6 | GND 5 | 8 | =========================================== http://www.dontronics.com/dt001cha.html thanks Don. =========================================== Somebody please correct my if I am wrong! Most of the pins make sense. BTW, has anybody done such a replacement (F84 -> 508/509) in burning pics and had it worked? Later. +--------------------------+ | Sep Seyedi | | -> sep@hypervr.com | | -> http://sep.2y.net | +--------------------------+