Remarkably, sending this entire mixed-data byte directly to system port 61h, which historically manages various low-level motherboard controls, does not disrupt the system. In standard DOS environments and modern emulators, pushing these extra bits to the port is effectively harmless.
If anyone is curious what the other bits do and how the PC speaker really works:
If anyone is curious what the other bits do and how the PC speaker really works:
https://fd.lod.bz/rbil/ports/keyboard/p0060006f.html#table-P...
https://forum.vcfed.org/index.php?threads/pc-speak-technical...
...and I wouldn't be surprised if some chipset put more hazardous functionality in those reserved bits.