Quick Tutorial on De Morgan's Laws It's not a "theory", it's "the Law"!! ;-> It's MATH. It works or it doesn't!! No testing required after it works right. ;-) DeMorgan's Laws. They are written as /(AB)=(/A)+(/B) and, /(A+B)=(/A)(/B) and that's why they are plural, "..Laws". But the graphic principles with using the over-bar for "NOT"-ing equationally, and with GATES are: __ _ _ ___ _ _ 1) "Break the line/Change the Sign", AB = A+B and A+B = (A)(B) 2) The gate "sense" changes from OR to AND or from AND to OR when you PUT "balls" (inverters) where they weren't, and take them from where they were, on ALL inputs and output! ___ ___ ___ ___ A--| \ A-O\ \ A--\ \ A-O| \ | AND )O-C <==> ) OR )--C :AND: ) OR )O--C <==> | AND )--C B--|___ / B-O/___ / B--/___ / B-O|___ / P.S., It ALSO works with any inputs or output mixed as well, too!! Not JUST Both/All inputs vs output as shown here!! Example: ___ ___ ___ ___ A-O| \ A--\ \ A--\ \ A-O| \ | AND )O-C <==> ) OR )--C :AND: ) OR )O--C <==> | AND )--C B--|___ / B-O/___ / B-O/___ / B--|___ / Told you it was Quick!! -Steve -- -Steve Walz rstevew@armory.com ftp://ftp.armory.com:/pub/user/rstevew -Electronics Site!! 1000 Files/50 Dirs!! http://www.armory.com/~rstevew Europe:(Italy) ftp://ftp.cised.unina.it:/pub/electronics/ftp.armory.com