In a message dated 12/20/01 5:00:23 PM Eastern Standard Time, aiw@CYPRESS.COM writes: << It's worth noting that some UL standards require the microcontroller software to do things that simply can't be done with most PICs (e.g., perform a checksum calculation on the program ROM). >> If you use a 16F873 or 16F876 or 877, you can do a checksum. Cheers, Paul -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.