That is a pretty awesome tour de force. Somewhere deep inside your computer is an (emulated) PC/AT trying to get out :-).
An interesting lesson about the use of 'beep' for the assistive technologies. I see those sorts of things in architectures which have grown up over time and I wonder whether or not you could know at the time "Hey we're using this weird thing, please deprecated at your earliest convenience" or if it was more "there I fixed it."
Compatibility at the GPIO level was so ingrained in the PC community early on (there was even a code name for it, "Is it FlightSim compatible?" which referred to Microsoft Flightsim, a game that tested the compatibility limits of clones.) So as a tenet to the community all sorts of hacks could be committed in its name. Something like "Well we can depend on this, if they changed it then it would break compatibility and they can't do that."
Also an interesting take on how much Microsoft has had to unwind in a compatible way over the years.
Finally, the Linux console used to beep the speaker this way (I have no idea if it still does) and sometimes when I lay there sleeping I would hear my server softly feeping, yes feeping on its console bell. Sadly it wouldn't stop until I got up and logged in and figured out what was complaining.