I've created my own Startup file to be used that calls
cseg at 0
I've only included my startup file and not the sample. But it still overlaps at 0.
if the modified startup does not have the entry label and exit call you will get "startup missing" in commandline mode. I guess in the IDE mode that would make the standard get included. I imagine this is the part required:
?C_C51STARTUP SEGMENT CODE CSEG AT 0 ?C_STARTUP: ljmp ?C_START end
Ok. Thank you. I was missing a small part of that.