1. You're kindly welcome.

2. The last I had heard about that machine, specifically, was around 2011 and I'm fairly certain it was there when they eliminated the NOC in Detroit which was around 2013, if memory serves. The thing is, I would be surprised if it was actually gone.

3. Nice - I was well known was the guy who could fix anything over at Level 3 around the IT side of the house. Around 2014, I was asked to take a look at an ancient desktop PC that had been sitting in the server room at another building. It had failed weeks prior, had a modem plugged in and was discovered to have been used for a billing purpose that was apparently costing well into the 6 figures. The VP asked me if I would spare a moment to see if I could figure it out, despite it having nothing to do with my normal duties. It was dusty as heck and wouldn't boot -- nobody on the server team could get it functioning. I noticed a home-made label stuck to the top and recognized it as drive geometry. The little battery had failed, probably 15 years prior, and someone put a label on it figuring that people would understand exactly what it was. I was the only one who remembered what that was. When I made it boot, people stared at me like I was a magician. :)

Interesting... I think you just helped me figure something (admittedly rather simple) out. Quite trivial (not nearly as interesting as your experience), but mildly related.

Many years ago I happened to find an ancient-looking machine buried in a spare room at a church. I think the room was occasionally used as an ad-hoc creche area.

After finally locating an IEC cable for it and finally getting it to boot, I found that it was of the opinion it didn't have any HDDs attached.

So, I went into the BIOS, and - yes! Just old enough to require manual CHS configuration, but juuust new enough to have a manual autodetect routine!

Turned out it was a cute 25MHz-or-so (IIRC) 486 with something like a 200MB HDD. Had some demos on it that I've long forgotten the names of. Was fun to find that machine.

Despite being so trivial that no conveniently-placed homemade rescue labels were needed, the people there also wondered how I'd figured out what was wrong with it as well.

(Honestly, I really want to work somewhere everybody's still using ancient equipment. Partly because it's what I've been exposed to for most of my life and I really like it, and partly because I'm still yet to have the chance to acclimatize to newer stuff and almost all of the small bit of knowledge I've accumulated covers older tech.)

Regarding what you helped me figure out, I've been wondering for years why that BIOS decided it didn't have a HDD. Initially I thought the HDD was on the way out and decided not to show up one day, and the BIOS happily deregistered it [after someone saw an indecipherable POST error and hit F1 or whatever]. Now I wonder if maybe the rechargeable battery went flat after the machine was left off for ages, then someone turned it on, hit F1 to accept the "bad CRC" error (I never saw one) and didn't know to do an autodetect for the HDD. It's possible. I know some BIOSes remember "time wasn't re-set after fail"; I never saw a time POST error, and don't remember if I checked the clock to see if it was wrong.

> and I discovered in the (DR-DOS based) BIOS at one point that the serial port's electrical behavior can be customized between being edge triggered or level triggered.

Things like that make John Titor's IBM 5100 story slightly more believable. Old computers often have strange features which are omitted from their successors due to being rarely used (for instance, the original IBM PC could use current loop on its serial port connector). One could imagine someone with access to a time machine taking a short trip to the past just to grab one of these old computers as a replacement for a failed one.