Re: Floppy formatting questions

"itportal" <itportal@xxxxxxxxx> wrote in message
news:1178566367.345479.192330@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hello geeks,

I'm new to assembly and file systems. I'm trying to understand how
floppy disks work, but I cannot explain myself several things and I
though you could help me:

1. A normal 3.5'' formatted floppy disk is 1.44 MB, right? An
unformatted one is 2.0 MB? What does this format mean ... is it the
file system or not? Where are the missing 0.56 MB? I read somewhere
that it had to do something with the fact that the floppy disk secrots/
tracks (not sure which one of the two) are too near and generate
errors ... and therefore some are ignred...

A normal 3.5" 2mb unformatted floppy has the ability to store 2mb of data.
When you format it you write information to the floppy stating where the
tracks and cylinders are. Which is where it becomes 1.44mb. The 1.44mb
formatting gives track/cylinder information that is able to store 1.44mb of
data. If you gave different track/cylinder information, you could store 2mb
of data.

2. Can I write my own formatting program? I mean not only developing
my own file system, but also format the floppy disk so that it uses
not only 1.44 MB, but 1.68 MB for example, or why not the whole 2.0
MB...

Yes, you can. But you'd have to have a floppy driver (software) that was
able to understand your track/cylinder information. Also, very old floppy
disks were kind of hard coded for the 1.44mb and couldn't read 2.0mb
formatted floppies, which is why they were normally formatted to 1.44mb.

You might want to find the source code to some version of linux for their
format program and see what it is doing.

Go to wikipedia.org and type in floppy disk.


.

Relevant Pages

  • Re: [SLE] only root can write to floppy
    ... > floppy disk as a user. ... the diskette is not formatted or does not contain a file system of an ... Fdformat will only do a low-level format, ... There's also something called "gfloppy" that will appear relatively ...
    (SuSE)
  • Re: floppy disk controller broken
    ... when testing FreeBSD-7.1-BETA i discovered that the floppy disk ... controller doesn't work correctly. ... Processing fdformat: ioctl: Device not configured ... It looks like the ioctl to format a track used to never report failures from ...
    (freebsd-stable)
  • Re: Making disk images of NorthStar CP/M disks with Catweasel
    ... arbitrary hard sector floppy disk into the DMK format. ... format and another which decoded the DMK image into useful NorthStar ...
    (comp.os.cpm)
  • Re: Error Message: "No ID on Disk"
    ... After you perform a quick format on an unformatted floppy disk in Windows NT ... > Visit Topic URL to contact author (reg. ...
    (microsoft.public.windowsxp.help_and_support)
  • Re: How to enlarge 3.5"?
    ... The fd0 device is the first floppy disk in your computer. ... the name represents a different format. ... If you wish to format a floppy disk to 1.6 megabytes, then run this command: ...
    (Debian-User)