It's odd that he brings up things such as 100tpi drives (VS 96tpi)
and 3" (but not 3.25" on which Dysan bet the company), the very early 40
track 3.5",
On Sun, 10 Sep 2023, Joshua Rice via cctalk wrote:
What confused me, is that i believe the 3.5" Sony Microfloppy originally had
70 tracks. I'm personally completely oblivious to any 40-track 3.5"
microfloppy formats.
Yes, my sentence is twisted into knots :-)
I have a pair of Sony OA-D30V drives, which i believe were the first
commercially available 3.5" microfloppy drives, and they have a single head.
The format the machine that they're linked up to only uses 70 tracks (though
the drives might be capable of a few more?) for a SSDD format of 315KB.
Those were fascinating. 600 RPM and full height
40 track 3.5" microfloppy drives therefore seem more of a branching
derivative rather than the "predecessor" that the article seems to allude to.
Unless, of course, we're talking of an unrelated format that just used the
same size disks...
I agree that They were indeed, probably a derivative, rather than a
predecessor. Although I think that it was an early derivative. "Ordinary"
3.5" is 135 tpi with 80 tracks. Epson, and very few others, briefly tried
67.5 tpi, 40 track. Epson Geneva PX-8, etc. I had a 67.5 tpi drive from
another manufacturer, which means that somebody expected it to catch on,
or they thought that there would be a market for Epson accessories?
The early Sony Microfloppy is definitely not quite the standard "modern" 3.5"
floppy disk we're aware of today, but is still largely compatible with modern
disks, with slight modification. Namely the drives have no mechanism of
opening the shutters, so i've found the easiest method is taping the shutters
on the disks open with a bit of sellotape.
The apparently earliest 3.5" diskettes did not have a shutter. I have (or
had) a few labelled "Shugart". It is possible that those might have been
from a large batch of prototoypes for development, rather than
commercially available.
Then came manual "pinch" shutters. The user slid the shutter open, and it
latched. After removing the disk, the user pinches the corner of the disk
and a spring closes the shutter. The spot to pinch on the corner of the
disk had a tiny arrow pointing to it, and the word "Pinch".
Then came modern automatic shutters. The word "Pinch" is gone, but on
many of them, the arrow remained! At Comdex, somebody at one of the disk
manufacturers told me, "That arrow is a reminder of which direction to
insert the disk." I don't think that he believed me when I told him the
origin of the arrow.
--
Grumpy Ol' Fred [email protected]
