Alvin Did you set the the port to outputs? else: Check my homepage for setleds.asm if you use MPASM. It works for me with a 16c84 running from a 4MHz Xtal. Cheers! -- Eric van Es | Cape Town, South Africa mailto:vanes@ilink.nis.za | http://www.nis.za/~vanes LOOKING FOR TEMPORARY / HOLIDAY ACCOMODATION? http://www.nis.za/~vanes/accom.htm