> So when you run your program, some sort of ORG
> instruction sets the PC to a known value, which is the memory address you
> want your program to begin at.

No, no, no!  Beginners have enough confusion here.  We must be very precise
to avoid adding to it.

ORG is an assembler directive.  It tells the assembler where in memory to
put subsequent instructions.  It does NOT load the PC or cause anything else
to happen at run time.  On a power up or other reset, the processor
initializes the PC to 0 on most PICs.  After that it is completely up to the
code what happens to the PC, except for interrupts.  On an interrupt, the
processor sets the PC to 4, after saving the original PC value on the stack.
This applies to the 16xxx series, others have some other wrinkles.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, olin@embedinc.com, http://www.embedinc.com

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