What's the rarest or most unusual computer-related item that you own?

[Göran Axelsson]

A lot of interesting answers in this thread, here are a couple of my 
rarest ones.

The machine I appreciate the most is the NORD-1 that I rescued last 
summer. I'm working on getting it up and running. Originally built in 1972.
http://www.ndwiki.org/wiki/NORD-1_Serial_47
I've done some research and although only around 150 were produced it 
seems like at least 10 have survived and recides in museums or in 
collections at universities. Mine is the only one privately own I know of.

Other rare systems I have in my collection includes :
- DataPoint 2200 type A with serial dynamic memory, sadly incomplete and 
in bad condition.
http://www.home.neab.net/gandalf/ClassicComputing/Pictures/DP-2200/Datapoint-2200-type-A-001.jpg
- DataPoint 2200 type B with random access DRAM, complete but blew a 
fuse last time I tried to power it up.
http://www.home.neab.net/gandalf/ClassicComputing/Pictures/DP-2200/Datapoint-2200-type-B-001.jpg
Both systems have severe screen rot.

I also have an Alpha/LSI 16 bit OEM computer with 32kx16 core memory and 
a custom terminal. It is part of an EDS instrument that came with an 
electron microscope. When I powered up the system ten years ago it 
showed the last measurement, but when I pressed the reset button it 
crashed and just showed a line of @ at the top of the screen.
It's an interesting system and the architecture reminds me a lot of 
68000 CPU:s, including the possibility to stretch bus accesses 
indefinitely and running DMA so it would probably be an easy task to 
build a modern board to make an interface to debug it.
http://www.home.neab.net/gandalf/ClassicComputing/Pictures/Alpha-LSI/IMG_20160619_093851.jpg

At the software level I probably have a nuclear power station simulator. 
One of my computers ran a full scale simulator at one of the Swedish 
nuclear power plants around 1990. I haven't checked the disk yet but 
there is a good possibility that the software is still on the 70 Mbyte 
SMD disk.

Göran