TONY NIXON 54964 <PICLIST@MITVMA.MIT.EDU> wrote:

> Hey Andy, has Microchip ever offered you a job.

    Not one that I wa interested in taking, no.  However, my company
    DOES do a fair amount of consulting work for Microchip.

> It wouldn't surprise me if you and some others on this list know
> more about these devices than the engineers who designed them.

    I don't think so.

> Thanks for the help.
>
> On pondering the problem a little more, I guess the same situation
> applies if an interupt occurs when a GOTO or a CALL instruction
> precedes it.

    Yes, exactly.

> I can understand it a little more if I assume that the the
> interupt occurs in the following way....
>
> 1) IRQ is generated.
> 2) Current instruction is completed.
> 3) PC is Updated to point to next instruction.
>    This would equal either
>    i)   the address of the next inline instruction or an address
>         generated from the current instruction, ie.
>    ii)  a computed address (ADDWF PCL)
>    iii) a goto address iv) a call address
> 4) This address is pushed onto the stack
> 5) Jump to IRQ routine via 0004h
> 6) Retfie (Return) and execute from address pulled off stack.

    Correct.

    -Andy

=== Andrew Warren - fastfwd@ix.netcom.com
=== Fast Forward Engineering, Vista, California
=== http://www.geocities.com/SiliconValley/2499