"According to this document, there is still a Series/1 that "Coordinates the operational functions of the United States' nuclear forces, such as intercontinental ballistic missiles, nuclear bombers, and tanker support aircraft." This system still uses 8-inch floppy disks, however the agency plans to update some of the technology by the end of the 2017 fiscal year."
This article is more interesting for the glimpse into the world of the nascent personal computer movement (hijacked for three decades by MS) than for its conclusions about Unix's "trans"-portability.
The deft accommodation of endianness mismatch was eye opening. The world has settled firmly on little-endianess, but there are other similar incompatibilities always lurking, and always needing similar pragmatism.
Perhaps most surprising to me was that they did not lease access to a PDP-11 for long enough to do the port, instead of buying one. I have to guess that they actually really wanted one, anyway.
edit: going through Tor I can access it fine. Weird.