Where can i find original donkey kong game for pc for free??? help?

i cant figure out mame so i tried looking for the game i wanted for mame emulator but just to download. is there any site i can find the donkey kong game from the 80's for windows 7 ??? plllllz help............ oooo and same for original pacman or ms. pacman doest matter which. thx to all who can help :D