[TUHS] Control-T in UNIX

[Paul Winalski via TUHS]

Regarding ^T, VAX/VMS borrowed it from TOPS-20/TENEX.  It is implemented in
the terminal driver and can be enabled/disabled.  When enabled the terminal
driver does not treat ^T as part of the terminal's data stream.  Instead it
calls the asynchronous system trap (AST) routine that the process has set
up to capture ^T.  The DCL command interpreter's ^T AST routine sends a
broadcast message to the terminal containing the current date/time and
process status information.

-Paul W.