Marcel van Lieshout wrote: > Yes, the sample was for 18F452. > > I understand that the hardware must read the port to being able to > execute the xor. Would this be a problem? Yes, that's why you use the LATD register instead of PORTD on the 18 family. You can XOR to LATD just fine and you should get the intended result. ***************************************************************** Embed Inc, embedded system specialists in Littleton Massachusetts (978) 742-9014, http://www.embedinc.com -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body