imp@dancer.Solbourne.COM (Warner Losh) (07/24/90)
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 <std/disclaimer>
jlaiho@cc.helsinki.fi (07/25/90)
In article <1990Jul24.000651.7447@Solbourne.COM>, imp@dancer.Solbourne.COM (Warner Losh) writes: > 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? > I don't remember these thing by heart, but I recall there is a program called FDFORMAT, FDFORM15 or something similar. Anyway the program is an enhanced floppy formatter that allows one to make greater capacity diskettes than normal DOS would allow. The distribution package includes TP5.5 source code. Unfortunately for me the source was commented in German, so I could not read the functions of the program from comments; I had to read the code..:-) This program also formats normal capacity DOS disks using it's own procedures. I think it will have all the information you need included. > Warner Losh imp@Solbourne.COM > Boycott Lotus. #include <std/disclaimer> Juha Laiho jlaiho@cc.Helsinki.FI