Greetings, I am using the MPLAB simulator to debug and validate an application designed to run on a PIC16C73 controller. I am already using the pin stimulus file (.sti) and it seems to work ok. Can anyone describe the correct format for a register (.reg) stimulus file ??? Can anyone describe how a register stimulus file is actually used ??? The online help indicates that data is read from register file is read and placed in the appropriate register based on a program memory location. Is this done before or after the instruction at that address is executed ??? Bob Segrest