MO drives came in at least three major variations, distinguished by media: originally up to 520MB or so with 512 tracks then 680MB and beyond with 1024 byte tracks, and here's where the first OS issues occurred when they didn't inherently handle 1024 byte tracks-- solution: you need an updated driver AND usually a special formatting utility to format the disk. More recently there were multi GByte disks that were 5" or 5 1/4" or so too (obviously with a different drive mechanism). The 3 1/2" originals look like a thicker 3 1/2" floppy (still with rigid plastic case). All the MO drives I've used have had a SCSI interface and have worked very well. Another application was with the military due to rugged design and data integrity: the MO disk had to be written with both a laser AND magnetic head. The laser was used to spot heat the MO material and the magnetic head wrote the bit in place. It is the reason why they are much less susceptible to erasure or bit drop due to magnetic field interference. Some MO providers still have the drives available for download on the net and through their support chains. Hope this is of help. Geoff