Conversation so far:
when does the Michelangelo computer virus take effect every year?
In the case of Michelangelo, once the virus infects a computer, it remains dormant until a specific date—March 6 of each year, to be exact.
why did the Michelangelo computer virus take effect on March 6 every year?
the birthday of Renaissance artist Michelangelo

Question: what systems does the virus affect?
Self-contained rewrite: What computer operating systems does the Michelangelo computer virus affect?