Thanks for the link Bruce
It gave me direction... But now i need more advice..

How can i add two of this Dwords?
http://www.picbasic.co.uk/forum/showthread.php?t=1942

how do i know if the add of two words overflows?
i.e. $1FFFE + $2E

my guess is to add the lower words $FFFE+$2E. But how do i know if there is an overflow? so that i can add one to the higher WORD? even worse..

i.e. $EFFF8 + $6FFE4

My guess again: add two lower words... if over flow add two higher words +1, else add two higher words....

I Hope you or Darrel Can help me..

Thanks