forgot to thank you for the answers
what's funny is that not only are there two revisions, K easier and M harder, but also you can adjust the difficulty in detail through dipswitches
http://www.vgmuseum.com/mrp/hcast/manual-jhcast.htmso i'm more confused, does that mean M and K are just the same board, set to different dipswitches, or are they different software revisions which can be FURTHER finetuned with dipswitches.
if i were rich id buy both boards to find out, but this isn't going to happen
here's what the switches do
adjust coins for player1/2 (1~4 coins for 1~7 plays)
adjust difficulty (easy, normal, difficult, very difficult)
adjust player strength (strong, normal, weak, very weak)
now if i have an M version and a K version both set to the same switches, you can do a comparison to see what's been altered
i suppose there are more alterations than the dipswitches, like enemy respawn, speed, etc.
whew