Library /sys$common/syshlp/sysgen.hlb SHOW, /UNIBUS, Description  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    The SHOW/UNIBUS command reads all device registers. For some
    controllers, the result might be reading a character out of
    a buffer or some other undesired action. Therefore, use the
    SHOW/UNIBUS command only when you debug a UNIBUS configuration.
    On a system with more than one UNIBUS adapter, the command shows
    only the address of the first UNIBUS adapter.

                                   NOTE

       Never use the SHOW/UNIBUS command on a running system.
       Use of this command is valid only during a conversational
       bootstrap.