11 Jun
2026
11 Jun
'26
12:46 p.m.
On Thu, Jun 11, 2026 at 3:31 PM Tom Gardner via cctalk
<cctalk(a)classiccmp.org> wrote:
“Then 3.5"
The Epson PF10 had 40 cylinders with 67.5 tracks per inch, but
everybody else immediately went to 135 tpi, …”
• The first 3½-inch is generally accepted as the Sony OA-D30V shipping in
1981 at 135 tpi. There were earlier drives smaller than the 5¼-inch. The
Epson PF-10 was much later circa, 1984
I think I have one or two Sony OA-D3XV drives, I'd have to go up in
the attic to look for a never-released terminal server product I
worked on in 1984-1986 to find out exactly which model. I remember it
had a chunky full-height Sony 3.5" drive but I don't remember if it
was so old we had to pinch the shutter on the diskettes or if it had
an autoshutter mechanism. The first 3.5" drives I used were on a 128K
Mac, around July/August 1984 and I definitely wasn't pinching the
shutter on those.
-ethan