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The number of tracks in a floppy disk!?

Posted: Tue Feb 02, 2010 12:33 pm
by pySnake
I have read this from tutorial 5 of OS Development series: http://www.brokenthorn.com/Resources/OSDev5.html
There is 18 sectors per track. There is 63 tracks total on floppy disks.


According to this: I think it's should be 80 tracks?

Regard,
pySnake.

Re: The number of tracks in a floppy disk!?

Posted: Tue Feb 02, 2010 4:00 pm
by Andyhhp
You are correct in that 63 is wrong - it should be 83.

Yes - 1.44MB floppy disks have 80 tracks (technically cylinders if you have more than 1 platter) * 18 sectors per track * 512 bytes per sector * 2 heads per platter = 1.44MiB

However, when writing your own Floppy disk controler, it is possible to tweak parameters and get 83 cylinders, giving you a 1.49MiB floppy disk (Windows 95 distrobution is an example of this)

~Andrew

Re: The number of tracks in a floppy disk!?

Posted: Tue Feb 02, 2010 11:23 pm
by Mike
Hello,

Yes I believe it is an error in the tutorial. There are several other errors with that tutorial and it is planned for an update. Sense some of the later FDC tutorials include the same content for completeness, they seem to also contain the same errors as well.

It will be corrected as soon as possible.

Re: The number of tracks in a floppy disk!?

Posted: Wed Feb 03, 2010 4:15 pm
by pySnake
Andyhhp wrote:However, when writing your own Floppy disk controler, it is possible to tweak parameters and get 83 cylinders, giving you a 1.49MiB floppy disk (Windows 95 distrobution is an example of this)

Tks a lot about this information, it's very helpful :).

pySnake.