I grew up very close to the HNF and spend a great time there during my childhood to the point that the employees all knew me by name. The museum took a great part in shaping me into the nerdy person that I am today and put me into the career-path that I am currently on. The museum is amazing and the exhibitions are always fascinating, I greatly recommend them to anyone who is ever in the area.
Here are some images of my Nixdorf 820. I also included some pictures of text where this particular Nixdorf was used.