The Queue I/O Request and Wait service queues an I/O request to a
    channel associated with a device.

    The $QIOW service completes synchronously; however, VSI
    recommends that you use an IOSB with this service to avoid
    premature completion.

    For asynchronous completion, use the Queue I/O Request ($QIO)
    service.

    In all other respects, $QIOW is identical to $QIO. For more
    information about $QIOW, refer to the description of $QIO.

    On Alpha and Integrity server systems, this service accepts 64-
    bit addresses.

    Format

      SYS$QIOW  [efn] ,chan ,func ,[iosb] ,[astadr]

                ,[astprm] ,[p1] ,[p2] ,[p3]

                ,[p4] ,[p5] ,[p6]

    C Prototype

      int sys$qiow  (unsigned int efn, unsigned short int chan,

                    unsigned int func, struct _iosb *iosb, void

                    (*astadr)(__unknown_params), __int64  astprm,

                    void *p1, __int64 p2, __int64  p3, __int64 p4,

                    __int64 p5, __int64  p6);