I meant an analogue sum.. I.e. going from 0+0 to 5+5 == 0>10V pulse > this won't work. (A && !B) gives no indication whether one or both inputs > changed. > > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body