First 3.5 inch FDD [WAS: RE: Prototype IBM DemiDiskette drive]

[Fred Cisin]

On Fri, 24 Aug 2018, Tom Gardner via cctalk wrote:
> As Chuck notes the shutter closing was different, the RPM was different 
> and the interface was quite different.  Also different was the media 
> coercivity, media thickness, data rate and physical drive form factor. 
> Enough differences such that the Sony 0A-D30 drive and medium could not 
> interchange with what became the industry standard for 3½ FDDs and FDs.
> What became the standard in all these areas and others was defined by 
> the "Microfloppy Industry Committee" which was formed and led by folks 
> from Shugart Corp.  At its peak it had at least 23 members.  In January 
> 1983 Sony agreed to supply media comporting to the MIC standard.  Both 
> Tandon and Shugart showed drives at Comdex 1982; who shipped first in 
> 1983 is unknown.

THANK YOU for all of the details!

As to the shutter:
There were early diskettes with NO shutter.  I have one with a "Shugart" 
label.   It's POSSIBLE that it was only a prototype?

There were some with completely manual shutters.

There were "Pinch" diskettes.  You manually opened the shutter against 
minor spring tension, and it latched.  To close it, you pinched the corner 
of the housing, and the spring closed the shutter.  There was a word 
"Pinch" imprinted in the corner, and an arrow pointing to it.  I had most 
of a box of new HP ones of those at VCF.  A guy scammed the consignment 
staff into letting him walk away with the whole box at the "price per 
ONE disk" price.

Then came the completely automatic diskettes that everybody is faamiliar 
with.  They stopped imprinting the word "Pinch", but they left the arrow!
(under the premise that "it shows which way to put the disk into the 
drive")

I used no shutter diskettes, manual shutter diskettes, "pinch" diskettes, 
and automatic shutter diskettes in Shugart SA300 automatic shutter drives.
You had to be a little careful of the shutter in the early drives.


If there were differences in the media coercivity or media thickness, 
they were minor enough to not prevent my using the wrong ones.

Do people using the Sony drives have difficulty using the other diskettes?

      This, of course, is NOT the same issue as the differences between 
"720K/800K" diskettes V "1.4M"/"HD".
      The "720K/800K" were about 600 Oersted, and "1.4M"/"HD" is somewhere 
around 720 to 750 Oersted.  Unlike "360K" V "1.2M" (300 Oersted V 600 
Oersted), the difference between the 3.5" diskettes is close enough thet 
many people are not aware of it, and misuse a good 3.5" diskette as a 
mediocre one in the wrong drive.
      "1.4M"/"HD" diskettes have an extra hole identifying the media; some 
drives have sensors looking for that; some (including many PS/2) don't.
      "ED"/"2.8M" has a different material for the cookie (Barium-ferrite), 
and a slightly different media ID hole.


Drive form factor was not much of an issue - to retrofit a 3.5" drive into 
a PC, you had to make your own mounting brackets anyway (Erector Set). 
Soon, there became available trays to put a 3.5" drive into a half-height 
5.25" bay.

RPM, Data transfer rate is a minor issue.
The 600RPM of the Sony drive requires a 500,000 bits per second data 
transfer rate (like an 8" or "1.2M")


Another variant to be aware of:
NEC has 3.5" drives that are 360RPM (like an 8" floppy), instead of 
300RPM.  That lets them have the same structures on the diskette for 8", 
5.25" "1.2M", and their 3.5" format.  (77? track, 8 sector, 1024 bytes 
per sector) Those drives are sometimes referred to as "Type 3" or "3 
Mode",

Some OEMs used 3.5" with CP/M.
Some OEMs modified MS-DOS to support 3.5"
MS-DOS 2.11 made that much easier than it had been with previous versions.
PC-DOS 3.20 was the first official support of 3.5" from IBM.
PC-DOS 3.30 was the first official support of "1.4M" from IBM.
MS-DOS 3.31 was, like 2.11, often customized, including HDD larger than 
32M. etc.


As to "FIRST". . . .
The word should be avoided in all historical research.
Few are willing to acknowledge the possibility of a "tie".
But, often one company is the first to announce, another is first to have 
a working prototype, another is first to demo, another is first to start 
taking orders, another is first to ship their first one, another is first 
to be able to supply without long pre-order, another . . .
Apple/TRS80/PET had overlaps of which phase of being first each one was.

And, LITTLE guys are ignored when a BIGGIE comes out with the same thing.
E.g., Osborne was most definitely NOT the first to come out with a "sewing 
machine"/"suitcase" computer.  In fact, right across the aisle from the 
many thousands of dollars of chrome and black plexiglass of his big 
announcement, Elcompco (in a corner of the Berkeley Microcomputer/XenoSoft 
booth) was fulfilling orders for a machine with floppy drives and 5" 
monitor built into a Halliburton attache case.


So, for my PERSONAL meaning of "first", Shugart SA300 was the first 3.5" 
drive with "standard" interface that I could buy at a computer swap and 
carry home.

--
Grumpy Ol' Fred     		cisin at xenosoft.com