> I have been using the PICs for about two years now and every now and > then I see the macro ORG. What is that for? I have never had a need to use > it, but if its usefull maybee I have been missing out on something. ORG is actually an assembler directive, not a macro. It is used in absolute code (one assembly module, linker not used) to set the address where the next thing you write into program memory will go. This is how you make sure your interrupt routine starts at the interrupt vector (address 4 for 16C PICs). I don't think I've personally ever used it since I like breaking code up into separate functional modules. This greatly enhances maintainability and code reusability. It is also the only way to get a separate scope for symbols local to a particular code chunk. However, multiple modules forces you to use the linker, which prohibits use of the ORG directive. The equivalent directive for relocatable code is the CODE directive. Of course you could also look in the manual for the answer to this question. ORG, CODE and a whole pile of other directives are all described there. It's worth a read thru for anyone doing PIC programming. How have you managed to program PICs for two years without ever having cracked the manual? How have you been locating the start of your interrupt routines? ***************************************************************** Olin Lathrop, embedded systems consultant in Devens Massachusetts (978) 772-3129, olin@cognivis.com, http://www.cognivis.com -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics