Nah, on actual x86 PC atx/etc motherboards the ports are frequently fully RS-232 compliant, and on all my desktop boards for the past few years are even still d

Nah, on actual x86 PC atx/etc motherboards the ports are frequently fully RS-232 compliant, and on all my desktop boards for the past few years are even still documented. Example: I have native, documented DB9/25 on my latest machine, an asus prime x570-pro https://www.asus.com/us/Motherboards-Components/Motherboards/PRIME/PRIME-X570-PRO/ https://www.asus.com/us/Motherboards-Components/Motherboards... which if you download the manual and search for "COM" you will see that it uses the semi standardized 10 pin motherboard header into which a card edge DB9/DB25 can be plugged into. They are overwhelmingly used by hw/firmware/bringup engineers, so, while your right they are frequently undocumented or unpopulated, like JTAG ports its more unusual not to find them. And, yah on a lot of machines they are just whatever logic level the chip supports for IO 1.8V/etc so its common to just wire the headers to FTDI/etc usb converters rather than level shifters.