What's the rarest or most unusual software item do you own?

[Lars Brinkhoff]

> What about software?

I guess the PDP-11 operating system TRANTOR would be my most unusual
piece.

   "Trantor was created by Steve Orszag of the MIT Applied Math
   department to access the CDC and Cray computers at NCAR for his fluid
   dynamics research.  NCAR expected people to access the systems with
   an expensive piece of equipment that read punched cards, sent off the
   data over a synchronous modem using a proprietary protocol, and then
   sent output back to the printer.  Not only was it expensive, who
   wanted to use punch cards? So Orszag bought a PDP-11 and hired
   undergrads to write software to use Emacs-like editing to create
   programs on the local harddrive, submit them using the proprietary
   protocol (which we sort of had to reverse engineer), and print and
   graph the results.  ECC, CBF, and I were the early developers (there
   were a host of undergrad and grad student users as well, doing fluid
   dynamics).  Somehow this was cheaper than the archaic method.
   Trantor was then a communications OS with built-in applications.  We
   did the development on MIT-MC using the PDP-11 assembler and
   emulator."

I recently found a copy and sent it to the original authors.