Since this topic comes up semi-frequently, here are links to the free play romsets for classic stern games:
http://tsqmadness.com/slochar/ZIP/mpu100-freeplayroms.zip
http://tsqmadness.com/slochar/ZIP/mpu200-freeplayroms.zip
These are JUST freeplay only roms, not dip settable. There is the no-timed Orbitor 1 rom with this freeplay style in it as well.
No other changes are made to the roms regarding any other gameplay.