Slowest-seeking floppy or hard drive ever made?

For 5.25" floppy drives: The Shugart SA400 had a 40ms track to track time. http://www.swtpc.com/mholley/SA400/SA400_Datasheet.pdf Anything much faster than that would have "popped the needle out of the groove" of the SPIRAL (NOT HELICAL) flat disk positioner (designed like a record (NOT "record" as in a file, but record as in ancient sound recording) It would be tempting to not bother supporting that, since the 35 tracks of the SA400 are a subset of the 40 tracks of any "360K" "standard" drive. BUT, the SA400 mechanism (SA390 without the logic board) was what Apple used for the Apple ][ drive. Eventually replaced by other drives. The need to recover data from disks that also have bad alignment might force the need to use the origianl drive. The Micropolis, with HELICAL LEAD SCREW was a little faster, and MUCH more reliable. Later drives, such as the MPI B51 (and eventually Tandon TM100) with split band positioner were much faster (5ms track to track) and more reliable in their stepping. Tandon TM100 became the defacto standard for 5.25" Qume-Trak 142 (5.25" half-height) broke the tradition of quick stepping. When used on the IBM "Portable" (luggable) and PC-Jr, When used at the default step times of PC-DOS 2.00, it would get excessive seek failures. It was actually one of the reasons why PC-DOS 2.00 had to be replaced with 2.10 (with slower step times). The first hit on Google claims 12ms, but at least the original early ones definitely could NOT manage better than about 25ms. -- Grumpy Ol' Fred cisin at xenosoft.com