[Leica] Another in the Computer History Museum series

[kcarney1 at cox.net (Ken Carney)]

Thanks for posting.  The photos are very interesting.  I remember seeing
photos of long banks of vacuum tube testers for tubes used in the B-52.  It
was explained to me that tubes were preferred because of resistance to EMP
effects in case of a nuclear war.  I thought I had seen all of the cold war
sci-fi films, but ran across "Red Planet Mars" with Peter Graves (1952) the
other day.  Watched it twice - it is hilarious.

Ken

-----Original Message-----
From: lug-bounces+kcarney1=cox.net at leica-users.org
[mailto:lug-bounces+kcarney1=cox.net at leica-users.org] On Behalf Of Herbert
Kanner
Sent: Friday, January 18, 2013 10:51 PM
To: Leica Users Group
Subject: [Leica] Another in the Computer History Museum series

In the early 1950's, there what was called the "Cold War". With the
realization the that Soviet Union had nuclear weapons and bombers capable of
getting here via the North Pole without refueling, some kind of defense
system became mandatory. The SAGE (Semi Automatic Ground Environment)
System, a multi-billion dollar system was developed. It had twenty one main
sites. The computers, which received radar information and then directed
fighter places, had forty-nine thousand vacuum tubes. Because this system
was to be operational 24/7, each site had two such computers, and the
magnetic drum memory units in the two were updated often enough so that they
could switch computers and the guys on what looked like radar displays
wouldn't know that they had switched. Here is the console of one computer.

http://gallery.leica-users.org/v/herbk1/L1002792.jpg.html

Here is a typical display unit that simulates a radar. If you look large at
the left side of the desk, you will see an ashtray and a socket for a
cigarette lighter (sign of the times--they didn't want the soldier to leave
the console for a cigarette break).

http://gallery.leica-users.org/v/herbk1/L1002795.jpg.html

There are several ironic facts about this muliti-billion dollar project.
First, the last of these units was decommissioned in 1983. For several years
prior, the threat was not bombers; it was intercontinental ballistic
missiles, for which this system was useless. Well before 1983, the West was
not manufacturing vacuum tube; every thing was transistorized. Guess where
we got the replacement tubes. From the Soviet bloc!

The next image shows a tiny fraction of a computer at MIT called Whirlwind.
It was the progenitor of SAGE. It also has an interesting story, which is
all about a remarkable guy named Jay Forrester. He was not only an inventor,
but an incredible project manager an negotiator. It all started around 1946
when the Navy wanted a flight simulator to use as a pilot trainer for planes
that had not yet been built, but that were on the drawing boards. They
believed they knew the flight characteristics. Because the only existing
digital computer was much too slow, it was clear that it had to be driven by
an analog computer. But those are hideously difficult to program, and soon
Forrester realized that the task was impossible. It had to be a digital
computer, but the several existing ones were still much too slow. So
Forrester set himself the task of speeding up digital computers by reducing
the word size and performing many operations in parallel that used to be
performed serially. I sa  w this computer--my best guess was in 1953. It was
imposing. Three of the four walls of the room were filled with panels
plugged with vacuum tubes. There was a very large cathode ray display tube
on which "real-time" displays could be seen. A favorite demo was the display
of the path of a bouncing ball. The image below was cooked up by the Museum
to show the front of a few panels and their vacuum tubes, and the rear,
showing components and wiring.

http://gallery.leica-users.org/v/herbk1/L1002818.jpg.html 

Whirlwind initially had a memory consisting of a bank of cathode ray tubes
(William's Tubes), a fast but unreliable memory. Someone called to
Forester's attention a new thingy called a "magnetic core," being used to
temporarily store bits in something called a "shift register" in a computer
at Harvard. Forrester disappeared into his lab for about eight months, and
came up with core memory. This became the standard computer memory for the
next twenty years until semi-conductor memory was invented.

When the Navy lost interest in flight trainers, Forrester persuaded them
that Whirlwind was the prototype for a Command and Control computer, aka
"Combat Information Center". There was a new contract. When that petered
out, he persuaded the Air Force that the computer could be an air defense
device. The tipping point was the "Cape Cod Experiment". There were enough
radars around that area to permit a demonstration where bombers would
"attack" Cape Cod and Whirlwind operators, using radar information, would
direct fighters to the bombers. This demonstration was so successful that it
launched the development of SAGE. IBM was the prime contractor; this put IBM
solidly in the computer business. 

Herbert Kanner
kanner at acm.org
650-326-8204

Question authority and the authorities will question you.





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