Siemens FDD200 configuration

[supervinx]

Hi! Got two FDD200, 8" drives. I revised their config with the manual handy. They seem OK for my needs (reading soft sectored IBM disks) except for a thing. They are configured for radial selection but with dedicated SELECT lines for heads/side. The first disk responds to SELECT lines 0 and 2, respectively for HEAD 0 and 1. The second disk responds to SELECT lines 1 and 3, for HEAD 0 and 1. This can easily be reverted moving a soldered wire jumper. I'd like to know why they were configured that way. I'll use the FDADAP adapter, BTW. Thanks!