Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!stan!dancer!imp From: imp@dancer.Solbourne.COM (Warner Losh) Newsgroups: comp.sys.ibm.pc.hardware Subject: 3.5" 720K format information wanted Message-ID: <1990Jul24.000651.7447@Solbourne.COM> Date: 24 Jul 90 00:06:51 GMT Sender: news@Solbourne.COM Organization: Solbourne Computer, Inc. Lines: 22 Greetings all, I'd like to get information on how 720K disks are formatted on an IBM PC when they are DD. I already know what the layout of the disks are, but I haven't seen a good explination of the logical sector to physical "track, head,sector" mapping. Also, how are the tracks numbered. How is this different than 5.25" floppies? The reason I ask all these questions is that I have a DEC Rainbow. Don't laugh. I'm trying to get a driver written that will understand 3.5" floppies so I can exchange software easily and have a good backup media (can't use 1.44M disks, because my controller isn't smart enough). Is there anything I need to know about them? Do they have different ID bytes, or sector number schemes? I can't seem to read/write any sector from any track that isn't track 0 on disks that have been formatted on a PC. Warner -- Warner Losh imp@Solbourne.COM Boycott Lotus. #include