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

    The IO SHOW BUS command lists all the buses, node numbers, bus
    names, TR numbers, and base CSR addresses. This display exists
    primarily for internal engineering support. You must have CMKRNL
    privilege to use IO SHOW BUS.