[comp.sys.ibm.pc.hardware] Any dual-head 360K/1.2M 5.25-inch floppy drives?

wales@valeria.cs.ucla.edu (Rich Wales) (05/18/91)

As anyone who has studied the issue will be aware, the recording head
designs in 360KB and 1.2MB 5.25-inch floppy drives are different.  This
means that the two types of drive are not totally compatible, even when
dealing with low-density (360KB) diskettes.  (Specifically, a disk that
has been formatted or written on by a 360KB drive cannot thereafter be
reliably written on by a 1.2MB drive.)

In theory, I'd suppose it would be possible to design a dual-density
5.25-inch floppy drive that could work properly with both kinds of disk.
Such a drive would presumably have either two sets of recording heads,
or else a single set of special heads that could somehow be made to act
properly in either 360KB or 1.2MB mode.

Does anyone know if such a drive exists?  If so, who makes it, what is
the model name/number, and about how much should I expect to pay for it?

--
Rich Wales <wales@CS.UCLA.EDU> // UCLA Computer Science Department
3531 Boelter Hall // Los Angeles, CA 90024-1596 // +1 (213) 825-5683

rich@aoa.UUCP (Rich Snow) (05/24/91)

In article <1991May17.214849.3103@cs.ucla.edu> wales@valeria.cs.ucla.edu (Rich Wales) writes:
>As anyone who has studied the issue will be aware, the recording head
>designs in 360KB and 1.2MB 5.25-inch floppy drives are different.  This
>means that the two types of drive are not totally compatible, even when
>dealing with low-density (360KB) diskettes.  (Specifically, a disk that
>has been formatted or written on by a 360KB drive cannot thereafter be
>reliably written on by a 1.2MB drive.)

I haven't seen this problem with any of the recent 1.2Meg drives. 
It is true that it occurred with the first generation of 1.2Meg drives.
I assume the positioning needed to be more accurate in order to assure
compatibility. It is quite a trick to double up the tracks in order to
make it compatible with 360K drives.

In fact, the new 'floptical' drives reliably read and write 360K format.
They get a greater track density by using an optical rather than purely
mechanical postioning system.

-Rich
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