E.g., why is it called a terminal emulator and not a terminal user interface? Why is there a "y" in pty if it stands for pseudo terminal? Why is it call it a "pseudo terminal" if it's acting like a communication pipe?
- The original terminal was a teletypewriter, printing onto paper, connected to a computer, usually through a serial interface. A teleltype is abbreviated "TTY", and the original Unix terminal interfaces were given the device file names /dev/tty, /dev/tty1, /dev/tty2, ... Those were the hard-defined terminals. Yes, these were communication pipes, handling stdin (keyboard), and stdout and stderr (the printer).
- As psuedo terminals came to be used, for users connected via "glass TTYs" (CRT terminals such as the venerable VT-100 and VT-200), or by entiirely virtualised terminals through remote connections (telnet, rsh) or windowing systems (W and X11), pty came to be used for pesudoterminal. Again, these were communication pipes. I used a variant similar to this VT-320, notable for its amber phosphr display: https://yewtu.be/watch?v=RuZUPpmXfT0
Yes, historical quirks.
You can still hook Unix up to a teletype, by the way:
The y in pty is because of tty.