/sys$common/syshlp/helplib.hlb CC, Run-time functions, [no]echo  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Curses Screen Management macros that set the terminal so that
  characters may or may not be echoed on the terminal screen.  This
  mode of single-character input is only supported with Curses.

  Syntax:

       #include <curses.h>

       echo()
       noecho()