What are the really unusual or weird computers?

Well, almost all of them have probably been migrating the same code from hardware to hardware for two decades already now. I have some appreciation for how the abstractions were done to make this possible. But: Literally, you could drop an AS/400 into my basement, along with all the software and all the manuals, and I would find myself unable to use it. I am that completely incapable of working in that architecture or (even worse) corporate mindset. Obviously lots of people do useful work in it all the time, but my quote-highly-trained-mind-unquote is simply unable to adjust to that mindset. I have written useful assembly code for 1802's, where any register can be the program counter. I have microcoded for AMD bit-slice. I have built my own logic devices out of vacuum tubes and relays. I have rewritten hairy device driver modules for hardware with bizarre undocumented side-effects on real-time OS's running $10Billion peripherals. I eventually figured out that to shut down a Windows box, you click on Start (that was a very tough hurdle for me - you'd be surprised!) Yet I cannot, and probably will never be able to, use an AS/400 application succesfully. The stumbling blocks for me are really that enormous. Tim.