I would appreciate any help getting past this problem. I am attempting to write code that I can use to update the program in flash memory. I am using the xc16x_iap-flash example and so far have successfully managed to locate the flash programming section to RAM and am able to erase and write to flash memory from it. The next part has me confused though. When I erase the sector 0xC00000 (beginning of flash memory) the program in RAM stops running. It appears as though constants from my program in RAM are being stored in flash. I assume that I am missing something in the L166 Locate Options, but after trying many combinations I am quite lost on how to set this up correctly. Keil xc16x_iap-flash example: http://www.keil.com/download/docs/xc16x_iap-flash.zip.asp