Well, I am working on a bootloader for the 18f46J11....

And came across this snipplet:

"To maintain the endurance of the program memory cells, each Flash byte 
should not be programmed more than once between erase operations. Before 
attempting to modify the contents of the target cell a second time, an 
erase of the target page, or a bulk erase of the entire memory, must be 
performed."

Add to that:  "The minimum erase block is 512 words or 1024 bytes."

This isn't a big problem for the bootloader (rewriting 1024K at a time 
is ok - a bit dangerous in page 0, but not a big issue).    What is bad 
is that this particular pic doesn't have any flash other than the 
program memory, so I in effect get to use the program memory as flash 
data memory to store my nonvolatile settings.

Assuming I am reading my datasheet correctly, that means I get to 
reserve 1024 of the 3776 bytes of RAM so I can read the entire block of 
configuration memory in, make modifications to it, and then re-write 
it.   Am I missing something? 

-forrest



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