🚀 go-pugleaf

In article <4407@pegasus.ATT.COM> psrc@pegasus.ATT.COM (Paul S. R. Chisholm) writes:
>In article <JACOBS.90Jan13171438@cmos.cs.utah.edu>, jacobs@cs.utah.edu
>(Steven R. Jacobs) writes:
>> Now I'm sure you will point out that the 1.44M microfloppy drives will
>> format/read/write data at 720K.  The reason that this works is that the
>> data is _exactly_ twice as dense, so that the 1.44M drive can write the
>> data on two neighboring tracks to make it look like 720K data.
>
>Nope; a 1.44M drive has twice the number of sectors per track, but the
>same number of tracks (of the same width and density) as the 720K.

Yes, I really blew it on this point.

>>                                                                 This is
>> not possible with the 1.2M drive, since 1.2M is not an integer multiple
>> of 360K (there are probably other complications as well).
>
> A 1.2M disk has exactly twice as many sectors per track, and twice as
> many (narrower) tracks, as a 360K disk.

This would mean that the high density disks are 1.44M instead of 1.2M
would it not?  I believe the high density disks are 15 sectors/track
while the 360K disks are 9 sectors/track.  This, with twice as many
tracks on the 1.2M floppies, accounts for the 1.2M size.

>  Paul S. R. Chisholm, AT&T Bell Laboratories
--
Steve Jacobs  ({bellcore,hplabs,uunet}!utah-cs!jacobs, jacobs@cs.utah.edu)