question:-how many OS can a PC have?
i know some of u may know the answer-
answer-5 i.e.one primary and four secondary.
now the question is how can any one load 5 primary OS on a single system?
a friend of my has done it on his PC ,but i don't know how he did it?
if anyone can answer?

i wanna add one thing my friend is on a tour so i get the answer when he comes back but i am just too curious to know.