Hi, I am trying to compile and run my program so that it utilises more than one core on my machine. I have looked at http://haskell.org/haskellwiki/Shootout/Parallel/BinaryTrees and am using parMap at a point in my code. I compile with ghc --make -O2 -threaded and run with the options +RTS -N5 The runtime complains that it doesn't understand the N option. I am running 6.10.4 on Windows XP. Cheers Mark