Here's one maybe you hadn't pondered...

The parallel port for printers ("centronics" /protocol/, not connector) has been standard-enough for so long that basically all home printers that had it could be connected to basically all home computers that had it... 

So-common that computers (and dumb-terminals) with /serial/ printer-ports in need of a printer might just get a shiny-new /parallel/ printer and a serial-to-parallel converter for cheaper than a serial-printer...

So common that e.g. "print screen" is a friggin button in DOS, and CP/M has the ability to copy to its parallel port just as easily as to another file, via the same utility...

Then....

Doesn't it seem kinda strange that using the parallel port to transfer files (or, e.g. data-logging) to another *computer* is so rare? Sure, laplink, etc. Sure, most of those printer ports are *not* bidir... but the bidir mod was well-known by the PC/XT, and implemented in every PC/clone thereafter, and, of course, that was *right* when PCs were taking-over... replacing folks' Commodores and TRS80s and Kaypros, which folk fought hard to find ways to transfer their files from... ...for, frankly, many PC-generations thereafter... (e.g. kaypro lover *finally* admitted PC's were the only upgrade option by the 386 era)

So, then... by the friggin bidir-parport-era (late PC/XT), they could've just "printed" their docs to a friggin PC the same way they printed to printers....

All it takes is... a little bit of pin-remapping at the end of a straight-through printer cable, and a tiny bit of software (TSR?) to watch for and respond to the incoming "strobe" on a different pin (maybe paper-loaded?)...

I mean, it's really a wonder this hadn't become as-ubiquitous as the bidir mod itself. Even two PCs, laplink's having been so common...Or, heck, I've got at least two, maybe more, friggin serial-to-parallel converters... I always thought they were for hooking parallel printers to serial ports, (e.g. connect your VT100's printer port to a newer parallel printer)... but surely the *opposite* would be /exactly/ as-complex, (nearly *identical*) circuitry-wise, and those things were pretty-durn-common... so, now, your kaypro/TRS80/whatever can print directly to a terminal-emulator on the PC, just like every other BBS-accessing/file-downloading terminal-emulator folk'd already been familiar with... (and, again, nevermind things like data-logging! e.g. all these mainframes that output to teletypes... of course they could've output to VT100s, but they'd only retain 25 rows of text... but now a friggin PC could stream straight to a floppy... scrolling... etc...)...

I mean, it just seems weird this stuff wasn't so commonplace that I'm sitting here, now, with a kaypro that can print logic-analyzed waveforms to "any" printer (setial *or* parallel, your choice!) and after some 30+ years of working with systems as-ubiquitously-/compatible/ as-aforementioned, it actually took me some /thought/ (as opposed to recollection of many prior experiences; because I, surprisingly, haven't had many) to figure out how to transfer the waveform data to a file on another computer... when, frankly, the OMNI4's friggin software has essentially the same "print screen" button, compatible with "any" printer (parallel OR serial, or friggin terminal application) that every computer has had for the past 45 years!