General :: How Is Shell History Specific To Each Tty

How is shell history specific to each tty? I can't see anything in the history files that would indicate which tty a command was performed on, however if I restart and log in on several ttys, the command order and history is preserved on each. How is this accomplished? This goes for zsh and bash equally.Now for some zsh specific questions.I had a saved webpae, which resulted in a file called doku.php.htm, and a directory called doku.php_files - I could only get zsh to expand the directory. It didnt seem to give me the option to cycle nor did it only complete as much as it could with ambiguity, i.e. to doku.php , so what is this behaviour and where can I read about it?

Secondly I would like to know why zsh interactive shells do not expand the PS1 prompt completely. Whenever I open an xterm or such, the prompt is not the normal PS1 prompt. I read through the manuals and config files, and could see nowhere that staed a different prompt should be used depending on the shell type. Why does this happen, and how can I modify this behavior?Regarding modules, if I install the compat-wifi modules which I assume replace the existing ones, how would I uninstall them? Would I just reinstall the normal kernel modules over them?