diff --git a/prototypes/base/include/multiboot.hpp b/prototypes/base/include/multiboot.hpp
new file mode 100644
index 0000000..186eed9
--- /dev/null
+++ b/prototypes/base/include/multiboot.hpp
@@ -0,0 +1,114 @@
+#pragma once
+
+#include <inttypes.h>
+
+
+#define MB_MEMSIZE (1<<0)
+#define MB_BOOTDEVICE (1<<1)
+#define MB_COMMANDLINE (1<<2)
+#define MB_MODULES (1<<3)
+#define MB_SYMS_AOUT (1<<4)
+#define MB_SYMS_ELF (1<<5)
+#define MB_MEMORYMAP (1<<6)
+#define MB_DRIVES (1<<7)
+#define MB_CONFIG_TABLE (1<<8)
+#define MB_BOOTLOADER_NAME (1<<9)
+#define MB_APS_TABLE (1<<10)
+#define MB_VBE (1<<11)
+
+#define MB_ASSERT_SIZE(type, len) static_assert(sizeof(type) == len, "multiboot::" #type " must be " #len " bytes large.")
+
+namespace multiboot
+{
+  struct MemoryMap
+  {
+      uint32_t entry_size;
+      uint64_t base;
+      uint64_t length;
+      uint32_t type;
+  } __attribute__((packed));
+
+  MB_ASSERT_SIZE(MemoryMap, 24);
+
+  struct Module
+  {
+      uintptr_t start;
+      uintptr_t end;
+      const char * name;
+      uint32_t reserved;
+  } __attribute__((packed));
+
+  MB_ASSERT_SIZE(Module, 16);
+
+  struct Drive
+  {
+      uint32_t size;
+      uint8_t number;
+      uint8_t mode;
+      uint16_t cylinders;
+      uint8_t heads;
+      uint8_t sectors;
+      uint16_t ports[0];
+      // 0x10	size-0x10	drive_ports	I/O-Ports, die von diesem Gerät benutzt werden
+  } __attribute__((packed));
+
+  static_assert(sizeof(Drive) >= 10, "multiboot::Drive must be at least 12 bytes large.");
+
+  struct APMTable
+  {
+      uint16_t version;
+      uint16_t cseg;
+      uint32_t offset;
+      uint16_t cseg_16;
+      uint16_t dseg;
+      uint16_t flags;
+      uint16_t cseg_len;
+      uint16_t cseg_16_len;
+      uint16_t dseg_len;
+  } __attribute__((packed));
+
+  MB_ASSERT_SIZE(APMTable, 20);
+  
+  struct Structure
+  {
+      uint32_t flags;
+      uint32_t memLower;
+      uint32_t memUpper;
+      uint32_t bootDevice;
+      const char * commandline;
+      uint32_t moduleCount;
+      Module * modules;
+      union {
+          struct {
+              uint32_t tabsize;
+              uint32_t strsize;
+              uint32_t addr;
+              uint32_t reserved;
+          } __attribute__((packed)) symsAssemblerOut;
+          struct {
+              uint32_t num;
+              uint32_t size;
+              uintptr_t addr;
+              uintptr_t shndx;
+          } __attribute__((packed)) symsELF;
+      };
+      uint32_t memoryMapLength;
+      const MemoryMap * memoryMap;
+      uint32_t drivesLength;
+      const Drive * drives;
+      uintptr_t configTable;
+      const char * bootLoaderName;
+      const APMTable * apmTable;
+      struct {
+        uint32_t ontrolInfo;
+        uint32_t modeInfo;
+        uint16_t mode;
+        uint16_t interfaceSegment;
+        uint16_t interfaceOffset;
+        uint16_t interfaceLength;
+      } __attribute__((packed)) vbe;
+  } __attribute__((packed));
+  
+  MB_ASSERT_SIZE(Structure, 88);
+
+}
\ No newline at end of file
diff --git a/prototypes/base/include/pointer.hpp b/prototypes/base/include/pointer.hpp
index 8b4838d..b8bd749 100644
--- a/prototypes/base/include/pointer.hpp
+++ b/prototypes/base/include/pointer.hpp
@@ -71,7 +71,7 @@ public:
 };
 
 template <class T>
-pointer<T> pointer<T>::invalid(uint32_t(0));
+pointer<T> pointer<T>::invalid(uint32_t(0xFFFFFFFF));
 
 struct physical_t_ident;
 struct virtual_t_ident;
@@ -86,4 +86,7 @@ using physical_t = pointer<physical_t_ident>;
 /**
  * A pointer pointing to virtual memory.
  */
-using virtual_t = pointer<virtual_t_ident>;
\ No newline at end of file
+using virtual_t = pointer<virtual_t_ident>;
+
+
+static_assert(sizeof(physical_t) == 4, "pointer is not 4 byte wide.");
\ No newline at end of file
diff --git a/prototypes/base/init.cpp b/prototypes/base/init.cpp
index 03f4a90..7b6771f 100644
--- a/prototypes/base/init.cpp
+++ b/prototypes/base/init.cpp
@@ -4,6 +4,7 @@
 #include "pmm.hpp"
 #include "numeric.hpp"
 #include "pointer.hpp"
+#include "multiboot.hpp"
 #include "compat.h"
 
 extern "C" void init(void)