File name TR440_usenet.txtFrom: Prof Karl Kleine
Newsgroups: alt.folklore.computers
Subject: Re: Blinkenlights
Date: 11 Aug 2001 23:09:55 GMT
Organization: Fachhochschule Jena, Germany
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Message-ID: <[email protected]>
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Sergej Roytman wrote:
> A naive question. What did the blinkenlights on the old iron that had
> them, show? I had always assumed that they were tied to the machine's
> data- and address busses (with appropriate buffering), but then the
> things would be useless much of the time. On the other hand, the BLs
> [... deleted ...]
Story #2: crash analysis by Polaroid photo for Telefunken TR440
As a student of electrical engineering in the begin of the 70ies at
Ruhr-Universitaet Bochum, Germany, I had a student job in one of the
workshops of the university. As I also had some aquaintance with
the people and the machines at the computing center I got the job
of constructing and building a very special tripod for a Polaroid
camera: Upon a machine crash (or upon seeing a very peculiar pattern)
the operator would grab the camera with the attached tripod, hook
the rubber feet into the corners of the blinkenlights console
(everything was made to measure and fixed) and take a shnapshot.
Yes, that was a real snapshot of the machine state, with instruction
register, instruction address, the user registers, flags, etc.
After that, reboot.
The trick was to have a camera position slightly off center, as
to eliminated / minimize reflections of various lights in the room,
and at the same time get a good rendering of the on/off state of
the blinkenlights. The second issue was that the whole camera /
tripod assembly was fixed and that it lay in some corner of the
room in a cabinet, no adjustments to be made, just pressing the
shutter release for the operator and taking out the Polaroid.
The TR440 will be unknown to most readers here. It was a German
mainframe for scientific calculation, of which about 40 to 60
machines were built und mostly used in universities and research
facilities under heavy grants from the German government to have
a national computing force. Some of it's software was actually
rather advanced for the late 60ies / early 70ies, and I only found
some of the facilities again a decade later with VAX/VMS. The
machine itself is forgotten today; I found just one picture of
it on the web, but no technical information online. I only have
a minimal collection of printed material like the instruction
set summary. That branch of Telefunken was later bought by Nixdorf
and that in turn by Siemens. So there's nothing left :-(.
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