::Basically, yes. The track and sector are stored in the sector header of ::each sector, among other data. I suspect when you say "MFM" you mean "all the soft-sectored data storage schemes descended from the original IBM 3740 (FM) standard", in which case you're right. There are a few oddball hard-sectored drives that don't have any header at all on the data in each sector - hardware counters in the drive controller keep track of this stuff. Of course, once your head stepper starts stalling or your index sensor gets dusty, all sorts of nasty things happen with this scheme. And, even more rare, are some embedded-servo floppy disk systems where the location on disk is encoded in special formatting that cannot, in any reasonable way, be called a "sector header". -- Tim Shoppa Email: shoppa(a)trailing-edge.com Trailing Edge Technology WWW: http://www.trailing-edge.com/ 7328 Bradley Blvd Voice: 301-767-5917 Bethesda, MD, USA 20817 Fax: 301-767-5927