Set Segment Base Address


                 This function changes the 32-bit linear base address of
                 the specified selector.

            To Call

                 AX = 0007h
                 BX = Selector
                 CX:DX = 32-bit linear base address for segment

            Returns

                 If function was successful:
                 Carry flag is clear.

                 If function was not successful:
                 Carry flag is set.

            Programmer's Notes

                 o    This function  will fail if the selector specified
                      in BX is invalid.
                 o    Your program  should only  modify descriptors that
                      were   allocated    through   the   Allocate   LDT
                      Descriptors function.
                 o    The high  8 bits of the base address (contained in
                      CH) will  be ignored  by 16-bit implementations of
                      DPMI.   This is  true even  when running  on 80386
                      machines.