Date: Wed, 1 Mar 2000 17:29:50 -0500
Reply-To: David Beierl <dbeierl@IBM.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Beierl <dbeierl@IBM.NET>
Subject: Re: Bentley Manuals on CD-ROM :)
In-Reply-To: <v04220800b4e33cb25d80@[142.103.139.103]>
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At 05:05 PM 3/1/2000 , Tobin Copley wrote:
I believe Lief may be referring to the '10"' (actually 250mm, so a little
less) floppy drives manufactured under the Ubermodernwerk brand
"Supermodernfactory?" Was it housed in the Trabby plant?
and sold only in East Germany for about a year, around 1981, if I
recall. They were single-sided, half-density, and held 22K of data.
Kewl!
They were discontinued due to design problems and poor manufacturing
quality control.
Just like the 2/3-height 5 1/4" BASF drives I helped build. Interesting
example there of engineering myopia -- the original Shugart 8" had an
H-frame to clamp the disk when you shoved the drive door down. When they
started making 5 1/4 drives, everybody did the same. BASF essentially
folded the mechanism in half to get a 2/3 height drive, but the leverage
was incredible and the puck too shallow to center properly. There matters
stood until some bright spark at Tandon thought of using a rotating cam to
operate the clamp. They came out with a half-height 8", and within a year
everybody was building half-height 5 1/4 drives too. That worked, unlike
the BASF units.
The drive units were plagued with problems; for example, the vacuum tubes
used in them were of poor quality, and the drive motor created a
considerable magnetic field itself, often erasing data as the drive spun.
Gee, at 22K per disk they could have used a pencil and eraser...prolly
would have taken the heat better too. What size tubes, do you know? Did
they use a stepper? How many tubes? How big was it physically? Where can
I get one?
>As a matter of fact, I have a pile of these old 250mm disks, which I
>acquired through a surplus outfit here. The tight, lint-free weave of the
>disks' battleship grey canvas fabric protective cover
Canvas? Canvas?? Oi vey. I would just *love* to see one.
>Just thought I'd help clarify the discussion regarding the 10"
>drives. Nice to see that Lief isn't the only listee with an interest in
>early computer hardware!
Amazing. Obviously the Deutsche Methode inaction (or is it "in action?").
:)
david
David Beierl - Providence, RI
http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"
