Swing emulates the feel of a real drummer in a pattern to sum it up.......50% swing means there is no offset of your notes in reference to where the note would fall in the time signature....when you start increasing it adds a slight offset to where the note would fall in a normal time signature ( a more human feel)..I have seen the one in Fruity loops it sort of does it but it's nothing like an mpc or Sp1200, it tries to do the same thing as the classic machines like the SP1200 and MPC60/3000, if you listen to some 70's records there is a sort of swing to how the funk patterns ares laid down....early hip hop 50-54% actually took that feel in a lot of the patterns, it sort of defined the feel of hip hop, the head bobbin element, you don't actually have to add swing but it might fall short........most musical forms that rely on a constant pattern have some degree of swing, Jazz is another one but it might have more of a swing than funk 60% and up and therefore hip hop..........another note most of the early drum machines were actually made to simulate a drummer as closely as possible for production sake......these machines provided the backbone for hip hop classics that till this day are still sought after to make classic hip hop beat patterns.
Oh yeah this is not a copy and pasted article but I know you could go out and find a better article on the subject I only know some of this because I have owned at least 9 different drum machines and just reading some of the old manuals i have especially from the SP12 & the SP1200 they break it down too.