The TTY Demystified tells you everything you need to know (and quite possibly more) about the *nix tty history. (If you do need to know more than this, you are probably already writing your own *nix kernel, or at least libc)
Hopefully that should give some insight into the terminfo, and other obscure details of the *nix kernel and its obsession with piping characters from one place to another.
*nix Shell 