> Aha! I am beginning to smell a rat. In MPLAB 5.70.40, the program memory > window is useless! That's exactly the same version I am using, and the program memory window is very useful. Of course I didn't mess it up by installing a complier into it . > This sounds like an MPLAB issue to me. It does not > display opcodes, it just displays a hex dump of program memory. No, you just don't have the mode set right. The program memory window has three modes. You have it set to "hex code display". The other two are "machine code display" and "disassembly display". Select either of the two others, then do an F6 (reset), and you will see a bar thru location 0 indicating where the program counter is pointing. Keep the focus on the program memory window and keep hitting F7 (step into), and you will see each instruction executed one at a time. The source code window will be useless during this process because it won't know what source line to associate with each instruction. I usually keep my program memory window in "machine code display" mode. The disassembler isn't as smart as it thinks it is, and usually picks the wrong symbol to display when multiple symbols happen to have the same value. This is more misleading than just seeing HEX target addresses. Usually I'm single stepping in the program memory window while having it track the source code in the source window as best it can. > Oh, why did I ever uninstall the old, stable version of MPLAB?? I find 5.70.40 is pretty good. It has all the same stupid things wrong with it that MPLAB has had for years, but it otherwise seems solid. A serious linker bug from a few months ago has been fixed. > Or at least, it behaves differently with a compiler than with assembler. That is still possible, but probably not. Are you willing to send me your HEX file? I don't need anything else to step thru your program other than knowing what processor it was built for. I'm actually a bit curious what the compiler does behind your back for the first few instructions. You can send it to me privately if you don't want to broadcast it to the list. ***************************************************************** Embed Inc, embedded system specialists in Littleton Massachusetts (978) 742-9014, http://www.embedinc.com -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu