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This past weekend, my wife and I, along with my brother and sister in law, paid a three-day visit to the city of Berlin. Although we spent most of our time there sightseeing, the direct occasion for our trip was that I had been offered an IBM I/O Selectric model 731.

About half a year ago, I had received a tip from my friend Dr. Bernd Ulmann, that a retiree of the Technical University of Berlin, Dipl.-Ing. Wolfgang Mahnfitz, wanted to find a good home for his IBM 731. After some e-mail conversation, in which I explained my intended use (as a console typewriter for my emulated IBM 360/65), he agreed to give the machine to me. We spent a short, but pleasant, time with Wolfgang and his wife, Ingrid, and I went home with not just the 731, but, as an added bonus, I got to take a character drum from an ICT (ICL) 1933 printer with me.


The 731, shown in the trunk of our car above, was used as a replacement for the console terminal on a Zuse Z-25 computer at TU-Berlin.

The picture above shows the added height (black part at the bottom of the machine) required for the switches and solenoids.

The ICT/ICL drum comes from a model 1933 line printer, capable of printing 1350 lines per minute, that was used with an ICT 1909 computer at TU-Berlin.


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  • This commment is unpublished.
    Andy_T · 10 months ago
    Can you maybe put a picture of the actual interface of this machine into the blog article?
    That would be very interesting to everybody interested in this kind of machine.