The first generation of 3½" MO drives could only use 128MB disks. The second generation 230MB drives can read and write 128MB and 230MB disks. Current 640MB 3½" drives can read and write 128MB, 230MB, 540MB and 640MB disks. (Early 640MB drives could only read from 128MB disks, however it may be possible to allow writing to 128MB disks by upgrading the drive's firmware.)

This backward compatibility means that if in the future you buy a higher capacity MO drive, you can continue to read and write all your existing MO disks using the new drive. 1.3GB 3½" MO drives will soon be available, and when they are you will be able to use all existing disks with the new drives. You can read about Fujitsu's prototype "Gigamo" 1.3GB 3½" drive on the Fujitsu Europe web site.