Hi Folks, I am building a PIC based terminal with a 40 X 2 Character display and 5 X 4 keypad. This interfaces to a PC through an RS232 port. I have the keypad and display working fine. I press a key, the proper character shows up on the display. I was also able to get the same character out the RS232 port. As the final stage in development, I attempted to enable interrupt driven RS232 receives so when a character arrived on the RS232 port, I could process it to the display. However, when I tried compiling this I received the following error: "Internal Error - Contact CCS => Code 20:585:6" According to the documentation, the error is in linking. I sent the code to CCS but thought I would ask if anyone has any ideas on this. Thanks. Bill -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.