Hi Craig, >If there is, where can I find it? You can find it at: http://www.vmdesign.com I also have a page at on my website: http://www.myke.com/UMPS I'm only pointing it out because there have been some issues with websites with the demo version. If you see any links to "http://www.sistudio.com", you're not going to find UMPS there (and chances are nothing at all). All the links on my page are up to date and correct. I've been using UMPS for close to eighteen months now and I really love it. I agree that it's expensive and I hate the dongle, but if you are working with different processors; there is no better tool. I've just gotten through designing a Dallas Semiconductor DS87C520 Board sensing 80 buttons and driving 80 LEDs and I was able to simulate the circuit ('574s and '245s are used for the I/O on a memory mapped bus) and have the code working with only one misprogrammed device. Philippe, how's it going getting UMPS to take Netlist input? myke Steven Hunter's "The Second Saladin" is my Book of the Week. http://www.myke.com/Book_Room/book1a.htm Also look at: http://www.myke.com/My_Books/homcu.htm for information on "Handbook of Microcontrollers" which has been named the Main Selection for November 1998 for the Electronics Book Club!