You can use the next macro (I'm not sure about 'display' directive keys, but you can clarify it in manual):
Код:
  macro safe_org
  if ($-\1)&#8000
  display "Warning! overwrite for ",\A,\1
  else
  org \1
  endif
  endm
And use it like this:
Код:
;some code
  ..
  safe_org 5000
  ;safe code
  ..
When the code areas are not overlapped, you will get usual org directive, which just changes current compile address. In case of overlapping, you will get warning message.