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

    TTY_RSPEED defines the receive speed for terminals. If TTY_
    RSPEED is 0, TTY_SPEED controls both the transmit and the receive
    speed. Maximum value is 17. This parameter is only applicable for
    controllers that support split-speed operations, such as the DZ32
    and the DMF32.