diff --git a/include/n64dd.h b/include/n64dd.h
index d2bf02c1c6..8c756ce692 100644
--- a/include/n64dd.h
+++ b/include/n64dd.h
@@ -3,16 +3,48 @@
 
 #include "z64scene.h"
 
+struct RegEditor;
+struct SaveContext;
+
+// TODO Use the specific pointer types instead of void*
+typedef struct n64ddStruct_800FF4B0_pointers {
+    void* unk_00;
+    void* unk_04;
+    struct RegEditor* unk_08;
+    void* unk_0C[31];
+    struct SaveContext* unk_88;
+    void* unk_8C[9];
+} n64ddStruct_800FF4B0_pointers; // size = 0xB0
+
+struct n64ddStruct_80121AF0;
 struct PlayState;
 
 typedef struct n64ddStruct_80121AF0 {
-    char unk_00[0x3C];
+    void (*unk_00)(n64ddStruct_800FF4B0_pointers*, struct n64ddStruct_80121AF0*);
+    void (*unk_04)(void);
+    char unk_08[0x34];
     void (*unk_3C)(void);
     void (*unk_40)(void);
     char unk_44[0x28];
     void (*unk_6C)(struct PlayState*, SceneDrawConfigFunc*);
 } n64ddStruct_80121AF0; // size = ?
 
+void func_800ADA80(void);
+void func_800ADAF8(void);
+n64ddStruct_80121AF0* func_800ADB30(n64ddStruct_80121AF0* arg0);
+void func_800ADB8C(void);
+n64ddStruct_800FF4B0_pointers* func_800ADBD0(void);
+void func_800ADC00(void);
+void func_800ADC08(s32 arg0, s32 arg1, s32 arg2);
+
+extern n64ddStruct_800FF4B0_pointers D_800FF4B0;
 extern n64ddStruct_80121AF0* B_80121AF0;
 
+extern u8 B_80121AE0;
+extern s8 B_80121AE1;
+extern u8 B_80121AE2;
+
+extern char D_801DA410; // type ?
+extern char D_801E8090; // type ?
+
 #endif
diff --git a/spec b/spec
index b91d55a22a..fd724b9c61 100644
--- a/spec
+++ b/spec
@@ -656,6 +656,15 @@ beginseg
     include "$(BUILD_DIR)/data/rsp.rodata.o"
 endseg
 
+#if PLATFORM_N64
+beginseg
+    // TODO
+    name "n64dd"
+    address 0x801C7740
+    include "$(BUILD_DIR)/baserom/n64dd.o"
+endseg
+#endif
+
 beginseg
     name "buffers"
     flags NOLOAD
diff --git a/src/code/code_n64dd_800AD410.c b/src/code/code_n64dd_800AD410.c
index 8b13789179..330b99bb59 100644
--- a/src/code/code_n64dd_800AD410.c
+++ b/src/code/code_n64dd_800AD410.c
@@ -1 +1,32 @@
+#include "ultra64.h"
+#include "z64dma.h"
+#include "segment_symbols.h"
+#include "n64dd.h"
 
+DECLARE_SEGMENT(n64dd)
+DECLARE_ROM_SEGMENT(n64dd)
+DECLARE_BSS_SEGMENT(n64dd)
+
+s8 func_801C7740_unknown(void);
+
+u8 B_80121AE0;
+s8 B_80121AE1;
+u8 B_80121AE2;
+
+void func_800ADA80(void) {
+    if (!B_80121AE0) {
+        DmaMgr_RequestSync(_n64ddSegmentStart, (uintptr_t)_n64ddSegmentRomStart,
+                           _n64ddSegmentRomEnd - _n64ddSegmentRomStart);
+        // TODO use _n64ddSegmentBssStart, _n64ddSegmentBssEnd
+        bzero(&D_801DA410, &D_801E8090 - &D_801DA410);
+        B_80121AE0 = true;
+        B_80121AE1 = func_801C7740_unknown();
+        if (B_80121AE1) {}
+    }
+}
+
+void func_800ADAF8(void) {
+    if (B_80121AE0 && (B_80121AE2 == 0)) {
+        B_80121AE0 = false;
+    }
+}
diff --git a/src/code/code_n64dd_800AD4C0.c b/src/code/code_n64dd_800AD4C0.c
index f75d79f5ef..858348d2bf 100644
--- a/src/code/code_n64dd_800AD4C0.c
+++ b/src/code/code_n64dd_800AD4C0.c
@@ -1,3 +1,90 @@
+#include "global.h"
 #include "n64dd.h"
 
+// TODO functions of unknown prototype
+extern char func_801C8510_unknown[];
+extern char func_800AE170_unknown[];
+extern char func_800ADCD8_unknown[];
+extern char osGetIntMask[];
+extern char osSetTime[];
+
+n64ddStruct_800FF4B0_pointers D_800FF4B0 = {
+    func_801C8510_unknown,
+    NULL,
+    NULL,
+    Fault_RemoveClient,
+    Fault_AddClient,
+    func_800AE170_unknown,
+    func_800ADCD8_unknown,
+    Fault_AddHungupAndCrashImpl,
+    Fault_AddHungupAndCrash,
+    func_800ADC08,
+    _Printf,
+    osCreateThread,
+    osDestroyThread,
+    osYieldThread,
+    osStartThread,
+    osStopThread,
+    osGetThreadId,
+    osSetThreadPri,
+    osGetThreadPri,
+    osCreateMesgQueue,
+    osSendMesg,
+    osJamMesg,
+    osRecvMesg,
+    osSetEventMesg,
+    osGetIntMask,
+    osSetIntMask,
+    osInvalDCache,
+    osInvalICache,
+    osWritebackDCache,
+    osWritebackDCacheAll,
+    osGetTime,
+    osSetTime,
+    osSetTimer,
+    osStopTimer,
+    &gSaveContext,
+    DmaMgr_RequestAsync,
+    DmaMgr_RequestSync,
+    DmaMgr_DmaFromDriveRom,
+    Cutscene_HandleEntranceTriggers,
+    gSegments,
+    Flags_GetEventChkInf,
+    Flags_SetEventChkInf,
+    NULL, // TODO possibly file padding
+    NULL,
+};
+
 n64ddStruct_80121AF0* B_80121AF0;
+
+n64ddStruct_80121AF0* func_800ADB30(n64ddStruct_80121AF0* arg0) {
+    n64ddStruct_800FF4B0_pointers* temp_a0 = func_800ADBD0();
+
+    if (arg0 != NULL && arg0->unk_00 != NULL) {
+        arg0->unk_00(temp_a0, arg0);
+    }
+    B_80121AF0 = arg0;
+    return B_80121AF0;
+}
+
+void func_800ADB8C(void) {
+    if (B_80121AF0 != NULL) {
+        if (B_80121AF0->unk_04 != NULL) {
+            B_80121AF0->unk_04();
+        }
+    }
+    B_80121AF0 = NULL;
+}
+
+n64ddStruct_800FF4B0_pointers* func_800ADBD0(void) {
+    D_800FF4B0.unk_04 = 0;
+    D_800FF4B0.unk_08 = gRegEditor;
+    D_800FF4B0.unk_88 = &gSaveContext;
+    return &D_800FF4B0;
+}
+
+void func_800ADC00(void) {
+}
+
+void func_800ADC08(s32 arg0, s32 arg1, s32 arg2) {
+}
diff --git a/tools/disasm/ntsc-1.2/functions.txt b/tools/disasm/ntsc-1.2/functions.txt
index 2a9b367e7e..75ffeb36b0 100644
--- a/tools/disasm/ntsc-1.2/functions.txt
+++ b/tools/disasm/ntsc-1.2/functions.txt
@@ -2304,13 +2304,13 @@ IrqMgr_HandlePreNMI500 = 0x800AD808; // type:func
 IrqMgr_HandleRetrace = 0x800AD82C; // type:func
 IrqMgr_ThreadEntry = 0x800AD8E4; // type:func
 IrqMgr_Init = 0x800AD9B8; // type:func
-func_800ADA80_unknown = 0x800ADA80; // type:func
-func_800ADAF8_unknown = 0x800ADAF8; // type:func
-func_800ADB30_unknown = 0x800ADB30; // type:func
-func_800ADB8C_unknown = 0x800ADB8C; // type:func
-func_800ADBD0_unknown = 0x800ADBD0; // type:func
-func_800ADC00_unknown = 0x800ADC00; // type:func
-func_800ADC08_unknown = 0x800ADC08; // type:func
+func_800ADA80 = 0x800ADA80; // type:func
+func_800ADAF8 = 0x800ADAF8; // type:func
+func_800ADB30 = 0x800ADB30; // type:func
+func_800ADB8C = 0x800ADB8C; // type:func
+func_800ADBD0 = 0x800ADBD0; // type:func
+func_800ADC00 = 0x800ADC00; // type:func
+func_800ADC08 = 0x800ADC08; // type:func
 Fault_SleepImpl = 0x800ADC20; // type:func
 func_800ADC5C_unknown = 0x800ADC5C; // type:func
 func_800ADCD8_unknown = 0x800ADCD8; // type:func
@@ -3097,6 +3097,8 @@ Message_Init = 0x800E2660; // type:func
 Regs_InitDataImpl = 0x800E2704; // type:func
 Regs_InitData = 0x800E35D0; // type:func
 njpgdspMainTextStart = 0x800E7200; // type:func
+func_801C7740_unknown = 0x801C7740; // type:func
+func_801C8510_unknown = 0x801C8510; // type:func
 n64dd_SetDiskVersion = 0x801C8808; // type:func
 ConsoleLogo_Calc = 0x80800000; // type:func
 ConsoleLogo_SetupView = 0x8080009C; // type:func
diff --git a/tools/disasm/ntsc-1.2/variables.txt b/tools/disasm/ntsc-1.2/variables.txt
index 29faa9c929..b949848748 100644
--- a/tools/disasm/ntsc-1.2/variables.txt
+++ b/tools/disasm/ntsc-1.2/variables.txt
@@ -12,3 +12,13 @@ gSaveContext = 0x8011AC80; // size:0x1428 type:SaveContext
 gRegEditor = 0x8011C0B0; // size:0x4 type:RegEditor*
 gSegments = 0x80121508; // size:0x40
 _string_n64dd_c = 0x801D9680; // size:0x1 type:char
+B_80121AF0 = 0x80121AF0; // size:0x4 type:n64ddStruct_80121AF0*
+B_80121AE0 = 0x80121AE0; // size:0x1 type:u8
+B_80121AE1 = 0x80121AE1; // size:0x1 type:s8
+B_80121AE2 = 0x80121AE2; // size:0x1 type:u8
+_n64ddSegmentStart = 0x801C7740;
+_n64ddSegmentRomStart = 0x00B8ADA0;
+_n64ddSegmentRomEnd = 0x00B9DA70;
+D_801DA410 = 0x801DA410;
+D_801E8090 = 0x801E8090;
+D_800FF4B0 = 0x800FF4B0; // size:0xB0 type:n64ddStruct_800FF4B0_pointers
diff --git a/undefined_syms.txt b/undefined_syms.txt
index c6d194e0cb..10eb929100 100644
--- a/undefined_syms.txt
+++ b/undefined_syms.txt
@@ -16,4 +16,14 @@ D_06000000 = 0x06000000;
 func_80001720 = 0x80001720;
 osInitialize = 0x80003230;
 
+// code_n64dd_800AD410.c
+func_800ADCD8_unknown = 0x800ADCD8;
+func_800AE170_unknown = 0x800AE170;
+osGetIntMask = 0x800CFBB0;
+osSetTime = 0x800D3660;
+func_801C7740_unknown = 0x801C7740;
+func_801C8510_unknown = 0x801C8510;
+D_801DA410 = 0x801DA410;
+D_801E8090 = 0x801E8090;
+
 #endif