VMS Help Sys Parameters, TTY_SPEED  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    TTY_SPEED sets the systemwide default speed for terminals. Low
    byte is transmit speed, and high byte is receive speed. If high
    byte is set to 0, receive speed is identical to transmit speed.
    Maximum value is 17. Baud rates are defined by the $TTDEF macro.