Library /sys$common/syshlp/dbg$help.hlb DEBUG, SET, VECTOR_MODE, Parameters  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 vector-mode-option

    Specifies the vector mode option. Valid keywords are as follows:

    SYNCHRONIZED    Specifies that the debugger force automatic
                    synchronization between the scalar and vector
                    processors whenever a vector instruction is
                    executed. Specifically, the debugger issues a
                    SYNC instruction after every vector instruction
                    and, in addition, an MSYNC instruction after
                    any vector instruction that accesses memory.
                    This forces the completion of all activities
                    associated with the vector instruction that is
                    being synchronized:

                    o  Any exception that was caused by a vector
                       instruction is delivered before the next
                       scalar instruction is executed. Forcing the
                       delivery of a pending exception triggers an
                       exception breakpoint or tracepoint (if one was
                       set) or invokes an exception handler (if one
                       is available at that location in the program).

                    o  Any read or write operation between vector
                       registers and either the general registers
                       or memory is completed before the next scalar
                       instruction is executed.

                    The SET VECTOR_MODE SYNCHRONIZED command does
                    not issue an immediate SYNC or MSYNC instruction
                    at the time it is issued. To force immediate
                    synchronization, use the SYNCHRONIZE VECTOR_MODE
                    command.
    NOSYNCHRONIZED  (Default) Specifies that the debugger not force
                    synchronization between the scalar and vector
                    processors except for internal debugger purposes.
                    As a result, any synchronization is controlled
                    entirely by the program, and the program runs as
                    if it were not under debugger control.