>Of course, if you really wanted to get tricky, you
>could break the code into small modules and just
>download corrections for the faulty parts.  Then patch
>the pointers to the replaced functions in the rest of the
>code.  I've seen that done on Z80 systems circa 1984.

Ahh, memories of BIOS jump tables in CP/M ...

Raises images of jump tables at page boundaries in a PIC, and having the
modules as page sized chunks ...

As to the earlier suggestion of multiple images in the external eeprom, I
have seen this done on spacecraft instruments, with a flag to identify which
one to load on instrument power up. However if the image is corrupted then
there is a facility to tell the ROM code to select a different boot image.
You cannot exactly go a service call to re-flash the image prom ...

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