At 06:54 PM 12/3/96 -0500, you wrote:
>     Hello,
>
>     What is the relationship between using the MPASM config directive and
>     actually writing your software to program the PIC configuration bits?
>     If config takes care of the bits, do the appropriate programming
>     instructions just magically get embedded into your machine code?
>     I have an example of config from Microchip:
>       __config  (_XMC_MODE & _EC_OSC & _WDT_OFF)
>     Note: These symbols are defined in p17c43.inc
>
>     Magic or not?
>
>     -Brian-


Brian,

No they don't. Using the MPASM's __config will only embed the configuration
in the .HEX file. This config is then available for an EXTERNAL programmer,
they do nothing for you if you wish to reprogram the config at RUN TIME -
IF that is possible and I'm not saying it is or isn't. (If I had to guess I
would say that it isn't. Can the TABLWT instruction access the config bits?
Somehow I doubt it.)

For those of you who are totally confused, the 17Cxx parts can be program
at run time with the use of the TABLWT instructions. This feature is
similar to the 68705's that can also be reprogram at run time. In actual
fact, both the 17Cxx and 68705 are always programmed at run time via a
bootstrap held in uneraseable ROM . That is why you  must supply a clock to
each during programming.


Jim