Hi All, For all who missed the 1980's technical details of diskdrives or lost the details in the mean time, I just put the "Training Manual Introduction to Magnetic Disk Drives" online which Philips provided in 1987 as part of a Field Training. The rest of the documentation are technical manuals of disk drives like the Shugart SA455/456, SA400L, SA800/801 and CDC 9406. Assuming those are available, so I won't scan them This manual covers floppy drives and hard disks, the latter with ST506 and SMD interfaces. http://electrickery.xs4all.nl/comp/divcomp/doc/TM_AItMDD.pdf http://electrickery.hosting.philpem.me.uk/comp/divcomp/doc/TM_AItMDD.pdf Enjoy & greetings, Fred Jan