diff --git a/lpc_nuvoton.hpp b/lpc_nuvoton.hpp
index eabcd09..c66653b 100644
--- a/lpc_nuvoton.hpp
+++ b/lpc_nuvoton.hpp
@@ -15,30 +15,42 @@
 {
   public:
     static std::unique_ptr<HardwareMapperInterface>
-        createNuvotonMapper(std::uint32_t regionAddress);
+        createNuvotonMapper(std::uint32_t regionAddress,
+                            std::uint32_t regionSize);
 
     /**
      * Create an LpcMapper for Nuvoton.
      *
      * @param[in] regionAddress - where to map the window into BMC memory.
+     * @param[in] regionSize - the size to map for copying data.
      * @param[in] a sys call interface pointer.
      * @todo Needs reserved memory region's physical address and size.
      */
-    LpcMapperNuvoton(std::uint32_t regionAddress,
+    LpcMapperNuvoton(std::uint32_t regionAddress, std::uint32_t regionSize,
                      const internal::Sys* sys = &internal::sys_impl) :
         regionAddress(regionAddress),
-        sys(sys){};
+        memoryRegionSize(regionSize), sys(sys){};
+
+    /** Attempt to map the window for copying bytes, after mapWindow is called.
+     * throws MapperException
+     */
+    MemorySet open() override;
 
     void close() override;
 
-    std::pair<std::uint32_t, std::uint32_t>
-        mapWindow(std::uint32_t address, std::uint32_t length) override;
-
-    std::vector<std::uint8_t> copyFrom(std::uint32_t length) override;
+    WindowMapResult mapWindow(std::uint32_t address,
+                              std::uint32_t length) override;
 
   private:
     std::uint32_t regionAddress;
+    std::uint32_t memoryRegionSize;
     const internal::Sys* sys;
+
+    /* The file handle to /dev/mem. */
+    int mappedFd = -1;
+
+    /* The pointer to the memory-mapped region. */
+    std::uint8_t* mapped = nullptr;
 };
 
 } // namespace ipmi_flash