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

       /CSR=csr_address

    Specifies the CSR address for the device being configured. This
    address must be specified in hexadecimal. You must precede the
    CSR address with %X. The CSR address is a quadword value that is
    loaded into IDB$Q_CSR without any interpretation by SYSMAN. This
    address can be physical or virtual, depending on the specific
    device being connected:

    o  /CSR=%X3A0140120 for a physical address

    o  /CSR=%XFFFFFFFF807F8000 for a virtual address (the sign
       extension is required for Alpha virtual addresses)

    This qualifier is required if /ADAPTER=tr_number is specified.