As the owner of
an IBM 5100 who is not so interested in selling it anytime soon, I do have the computer, and so I thank you for giving me advance permission to comment on your post
I promise even to discuss real-world information about the machine.
Who knows, if you read all of it, maybe I'll consider a swap. Probably not. It depends on what you consider to be of comparable value, I suppose...
I'm actually pretty amused by how the 5100 made its way into pop culture through a fanciful time travel story made up by some people on the late-'90s Internet. You may not know this, but the
John Titor legend went on to inspire parts of a Japanese novelistic video game called
Steins;Gate (punctuation intentional) that has sold over half a million copies. In the game, a computer called the
IBN 5100 (note N) is a time-travel
MacGuffin, and it's basically the same computer with some of the interface components moved around. I actually agree with the game designers that the screen is better placed in the centre of the front bezel, but it is preferable how the real computer locates the tape drive beneath the control switches instead of above them (otherwise the tape would get in the way).
I digress a bit. One of the most unusual things about the Titor stories is that they were one of the earliest online origins of the claim that the 5100 could emulate much larger computer systems. We know this to be true now, but at the time it was not widely known at all, and indeed IBM had deliberately kept this fact under wraps in order to avoid rousing awkward questions from customers (something I've confirmed with one of the 5100-series's designers --- so, there's some real-world information for you). You will note that
this systems paper about the 5100 does not really let on that this emulation is taking place, and neither do the various technical manuals you can find online.
Anyway, the author(s) of the Titor legend have never been identified for certain, but it's been supposed that they may have known or been related to someone who worked on the machine at IBM, and also our best guess is that they are two people from Florida. The 5100 originated from IBM's General Systems Division in Rochester, Minnesota (aside: with the
SCAMP prototype developed in the San Francisco Bay Area, it was difficult to find people from that project willing to move from sunny California to the wintry northern Midwest to help design a saleable product), but by the time the 5110 came out, development had
moved to Boca Raton, Florida, back into the balmy weather and not coincidentally where the 5150 emerged a little later. Florida is a big state, but at least it lends some credence to the "relative or acquaintance" hypothesis.
Anyway, isn't any of this at all interesting? The 5100 had some contemporary machines, depending on how you like to think about it. The MCM/70 that's also on your wish list, the Wang 2200, the HP 9830 --- all of these and some others are similar in capability, application, and price, but most of these are fairly obscure in comparison to a machine that hundreds of thousands of people have encountered, at least in a fictionalised form. I would propose that pop-culture stardom is probably why these machines are not so well-known and the 5100 is. It can't be just the PC precedent factor, either --- relatively few people have heard of the 5110, 5120, or the Datamaster (and the Datamaster gave us the ISA bus!), but hundreds of thousands have heard of the 5100 or at least a fictional derivative. And to me this fame is also a significant (if somewhat random) part of the 5100's story. Of course, it likely also accounts substantially for why you're having such a hard time finding one of your own.
That said, fame can help and not just hinder --- I suspect you owe a great deal of the value of your Apple I collection to pop culture, and perhaps even the existence of your machines. Without the popular infatuation with the two Steves (especially Jobs) and the legend of early Apple, I find it quite possible that the systems in your collection may have been binned before you got your hands on them!
Well, everyone in the retrocomputing hobby loves it for their own reasons, I guess. Personally I love the people history and the cultural connections around the machines, old and new, with
the joy of programming them a runner-up delight. Without these I'd find that they're mostly a way to keep yourself busy replacing capacitors. Now then, aren't you impressed by how much nonsense I had time for this evening?
