Our terminal driver.

Unix sends keyboard events to %dill from either the console or telnet, and %dill produces terminal output. The only app that should directly talk to %dill is the terminal app. Command-line apps are run by, receive input from, and produce output to, the %shell app, which is controlled by %terminal, which talks to %dill, which talks to unix. Clay also uses %dill directly to print out the filesystem change events, but this is questionable behavior.

%dill has two main components. First, it controls the terminal on a very basic, event-by-event level. This includes keeping track of things like the dimensions of the terminal, the prompt type (plain text or password), which duct to produce effects on, and so forth. Second, it handles terminal events, keystroke by keystroke. Most characters are simply pushed onto the buffer and blitted to the screen, but some characters, including control-modified keys, arrow keys, etc. require special handling. Most of the readline functionality is in %dill.