The TTY demystified (2008)

One of the most important commands I learned was "reset", especially when I was working with anything that would want to do something special. From the man page: "When invoked as reset, tset sets cooked and echo modes, turns off and raw modes, turns on newline translation and resets any unset characters to their default values before doing the terminal described above. This is useful after a program dies a terminal in an abnormal state." Except, it is also useful…

> Line editing...a backspace key is often useful. This could of course be implemented by the applications themselves, but in accordance with the UNIX design philosophy, applications should be kept as simple as possible. So as a convenience, the operating system provides an editing buffer Actually this is backwards. Line discipline is a historical artifact. Typically mainframes had IO front ends (AKA channel controllers) than managed IO so that the CPU (which BTW was what was charged for) could be…

What would a clean-slate implementation of a serial terminal look like today? I work in embedded, and a serial terminal is practically a must in any system, if only for debug. A way to provide input and receive output. You'll definitely want a FIFOs for RX/TX. You also likely want control chars and a way to shortcut the FIFO, if only to interrupt output. The FIFO means you can abstract away the exact physical communication medium. TUI interfaces mean you…

Things like this, with quirks due to decades and decades of history, always make me wonder what things would be like if we started over, with a clean slate. In so many places, when you start digging, you find something that references the way mainframes worked in the sixties or teletypes way before that etc. I mean, it's probably not practical, and it would probably be killed by committee or reimplemented in JavaScript anyway, but you can't help but wonder...