Originally Posted by StingRay
Disk swapping/extra disk has nothing to do with the trainer in this case. Game uses longtracks ($1900 bytes/track as opposed to $1600 bytes/track for a normal DOS track) thus the crack uses 1 disk more than the original. It also uses almost all of the available 512k RAM on a standard A500 which is the reason why there is no proper "Insert Disk" screen for the extra disk (no space for the patch).
Okay, that's interesting. It feels a bit strange that you have to insert the fifth disk as a filler for the other disks, but now I get why it was done this way. Thanks for the info StingRay