Hello, Piclisters, I need to make a simple square wave oscilllator, preferrably frequency adjustable, either with a pot or a BCD dip switches (don't have to be very exact!). It would be my first attempt to use this 12C508. Hopefully, somebody has done this before and don't mind to share the asm codes with me. I need it fast to replace a 555 chip oscillator. Thanks for all the help. Bill. _________________________________________________________ DO YOU YAHOO!? Get your free @yahoo.com address at http://mail.yahoo.com