INT 4B - Virtual DMA Specification - SCATTER/GATHER UNLOCK REGION
        AX = 8106h
        DX = flags
            bits 0-5 reserved (zero)
            bit 6: EDDS contains page table entries
            bit 7: EDDS may contain not-present pages (entry = 0000h)
            bits 8-15 reserved (zero)
        ES:DI -> Extended DMA descriptor structure (see AX=8102h) returned
                by AX=8105h
Return: CF clear if successful
        CF set on error
            AL = error code (see AX=8102h)
Note:   according to the Microsoft version of the VDS specification, the
          actual scatter/gather list is ignored, while according to the IBM
          version of the specification, "the result of a LOCK operation"
          must be provided to this function
SeeAlso: AX=8104h,AX=8105h

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