diff --git a/include/functions.h b/include/functions.h
index 71fbadb473..20dabac388 100644
--- a/include/functions.h
+++ b/include/functions.h
@@ -445,7 +445,7 @@ s32 __osSiRawWriteIo(u32 devAddr, u32 data);
 u32 __osSpGetStatus(void);
 void __osSpSetStatus(u32 value);
 void osCreateViManager(OSPri pri);
-void viMgrMain(OSDevMgr* iParm1);
+// void viMgrMain(OSDevMgr* iParm1);
 __OSViContext* __osViGetCurrentContext(void);
 void osWritebackDCacheAll(void);
 OSThread* __osGetCurrFaultedThread(void);
diff --git a/include/os.h b/include/os.h
index e9a5da37dc..568cc17942 100644
--- a/include/os.h
+++ b/include/os.h
@@ -8,6 +8,25 @@
 #define OS_READ     0
 #define OS_WRITE    1
 
+/*
+ * I/O message types
+ */
+#define OS_MESG_TYPE_BASE        10
+#define OS_MESG_TYPE_LOOPBACK    (OS_MESG_TYPE_BASE+0)
+#define OS_MESG_TYPE_DMAREAD     (OS_MESG_TYPE_BASE+1)
+#define OS_MESG_TYPE_DMAWRITE    (OS_MESG_TYPE_BASE+2)
+#define OS_MESG_TYPE_VRETRACE    (OS_MESG_TYPE_BASE+3)
+#define OS_MESG_TYPE_COUNTER     (OS_MESG_TYPE_BASE+4)
+#define OS_MESG_TYPE_EDMAREAD    (OS_MESG_TYPE_BASE+5)
+#define OS_MESG_TYPE_EDMAWRITE   (OS_MESG_TYPE_BASE+6)
+
+/*
+ * I/O message priority
+ */
+#define OS_MESG_PRI_NORMAL    0
+#define OS_MESG_PRI_HIGH      1
+
+
 typedef u32 OSIntMask;
 
 typedef u32 OSPageMask;
diff --git a/include/osint.h b/include/osint.h
index 71781ab6da..fa74a82eb6 100644
--- a/include/osint.h
+++ b/include/osint.h
@@ -20,4 +20,7 @@ typedef struct {
     /* 0x4 */ OSPri priority;
 } __OSThreadTail;
 
+extern __osHwInt __osHwIntTable[];
+extern __OSEventState __osEventStateTab[];
+
 #endif
diff --git a/include/variables.h b/include/variables.h
index 66f4ecc887..281996873f 100644
--- a/include/variables.h
+++ b/include/variables.h
@@ -88,8 +88,8 @@ extern __OSViContext* __osViNext;
 extern OSViMode osViModeFpalLan1;
 // extern u8 ldigs[];
 // extern u8 udigs[];
-extern OSDevMgr __osViDevMgr;
-extern UNK_TYPE4 __additional_scanline;
+// extern OSDevMgr __osViDevMgr;
+extern u32 __additional_scanline;
 // extern UNK_TYPE1 D_80098180;
 extern char bootThreadName[];
 extern char idleThreadName[];
@@ -352,9 +352,9 @@ extern OSPiHandle CartRomHandle;
 extern OSThread viThread;
 extern u8 viThreadStack[0x1000];
 extern OSMesgQueue viEventQueue;
-extern OSMesg viEventBuf[5];
-extern OSIoMesg viRetraceMsg;
-extern OSIoMesg viCounterMsg;
+// extern OSMesg viEventBuf[5];
+// extern OSIoMesg viRetraceMsg;
+// extern OSIoMesg viCounterMsg;
 extern u16 viRetrace;
 extern DmaEntry dmadata[1568];
 // extern UNK_TYPE1 D_80186028;
diff --git a/spec b/spec
index 27555435aa..d619034f3d 100644
--- a/spec
+++ b/spec
@@ -225,8 +225,6 @@ beginseg
     include "build/src/libultra/io/spsetstat.o"
     pad_text
     include "build/src/libultra/io/vimgr.o"
-    include "build/data/boot/vimgr.data.o"
-    include "build/data/boot/vimgr.bss.o"
     include "build/src/libultra/io/vigetcurrcontext.o"
     include "build/asm/boot/writebackdcacheall.text.o"
     include "build/src/libultra/os/getcurrfaultthread.o"
diff --git a/src/libultra/io/vimgr.c b/src/libultra/io/vimgr.c
index ecbb9b37cc..07babf3517 100644
--- a/src/libultra/io/vimgr.c
+++ b/src/libultra/io/vimgr.c
@@ -1,5 +1,107 @@
 #include "global.h"
+#include "osint.h"
 
-#pragma GLOBAL_ASM("asm/non_matchings/boot/vimgr/osCreateViManager.s")
+OSThread viThread;
+u8 viThreadStack[0x1000];
+OSMesgQueue viEventQueue;
+OSMesg viEventBuf[6];
+OSIoMesg viRetraceMsg;
+OSIoMesg viCounterMsg;
+OSMgrArgs __osViDevMgr = { 0 };
+u32 __additional_scanline = 0;
 
-#pragma GLOBAL_ASM("asm/non_matchings/boot/vimgr/viMgrMain.s")
+void viMgrMain(void*);
+
+void osCreateViManager(OSPri pri) {
+    u32 prevInt;
+    OSPri newPri;
+    OSPri currentPri;
+
+    if (!__osViDevMgr.initialized) {
+        __osTimerServicesInit();
+        __additional_scanline = 0;
+        osCreateMesgQueue(&viEventQueue, viEventBuf, ARRAY_COUNT(viEventBuf) - 1);
+        viRetraceMsg.hdr.type = OS_MESG_TYPE_VRETRACE;
+        viRetraceMsg.hdr.pri = OS_MESG_PRI_NORMAL;
+        viRetraceMsg.hdr.retQueue = NULL;
+        viCounterMsg.hdr.type = OS_MESG_TYPE_COUNTER;
+        viCounterMsg.hdr.pri = OS_MESG_PRI_NORMAL;
+        viCounterMsg.hdr.retQueue = NULL;
+        osSetEventMesg(OS_EVENT_VI, &viEventQueue, &viRetraceMsg);
+        osSetEventMesg(OS_EVENT_COUNTER, &viEventQueue, &viCounterMsg);
+        newPri = -1;
+        currentPri = osGetThreadPri(NULL);
+        if (currentPri < pri) {
+            newPri = currentPri;
+            osSetThreadPri(NULL, pri);
+        }
+
+        prevInt = __osDisableInt();
+        __osViDevMgr.initialized = true;
+        __osViDevMgr.mgrThread = &viThread;
+        __osViDevMgr.cmdQueue = &viEventQueue;
+        __osViDevMgr.eventQueue = &viEventQueue;
+        __osViDevMgr.accessQueue = NULL;
+        __osViDevMgr.piDmaCallback = NULL;
+        __osViDevMgr.epiDmaCallback = NULL;
+
+        osCreateThread(&viThread, 0, &viMgrMain, &__osViDevMgr, viThreadStack + sizeof(viThreadStack), pri);
+        __osViInit();
+        osStartThread(&viThread);
+        __osRestoreInt(prevInt);
+        if (newPri != -1) {
+            osSetThreadPri(NULL, newPri);
+        }
+    }
+}
+
+void viMgrMain(void* vargs) {
+    OSMgrArgs* args;
+    static u16 viRetrace;
+    u32 addTime;
+    OSIoMesg* mesg;
+    u32 temp = 0; // always 0
+
+    mesg = NULL;
+    viRetrace = __osViGetCurrentContext()->retraceCount;
+    if (viRetrace == 0) {
+        viRetrace = 1;
+    }
+
+    args = (OSMgrArgs*)vargs;
+
+    while (true) {
+        osRecvMesg(args->eventQueue, (OSMesg)&mesg, OS_MESG_BLOCK);
+        switch (mesg->hdr.type) {
+            case OS_MESG_TYPE_VRETRACE:
+                __osViSwapContext();
+                viRetrace--;
+                if (!viRetrace) {
+                    __OSViContext* ctx = __osViGetCurrentContext();
+                    if (ctx->mq) {
+                        osSendMesg(ctx->mq, ctx->msg, OS_MESG_NOBLOCK);
+                    }
+                    viRetrace = ctx->retraceCount;
+                }
+
+                __osViIntrCount++;
+
+                // block optimized out since temp is always 0,
+                // but it changes register allocation and ordering for __osCurrentTime
+                if (temp != 0) {
+                    addTime = osGetCount();
+                    __osCurrentTime = addTime;
+                    temp = 0;
+                }
+
+                addTime = __osBaseCounter;
+                __osBaseCounter = osGetCount();
+                addTime = __osBaseCounter - addTime;
+                __osCurrentTime = __osCurrentTime + addTime;
+                break;
+            case OS_MESG_TYPE_COUNTER:
+                __osTimerInterrupt();
+                break;
+        }
+    }
+}
diff --git a/src/libultra/voice/voicecontrolgain.c b/src/libultra/voice/voicecontrolgain.c
index 9dc541cc5c..d7ec8ef69b 100644
--- a/src/libultra/voice/voicecontrolgain.c
+++ b/src/libultra/voice/voicecontrolgain.c
@@ -1,3 +1,5 @@
 #include "global.h"
 
+u8 D_80098180[] = { 0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0 };
+
 #pragma GLOBAL_ASM("asm/non_matchings/boot/voicecontrolgain/osVoiceControlGain.s")
diff --git a/tools/disasm/files.txt b/tools/disasm/files.txt
index 3f921e7395..8dc09cca4a 100644
--- a/tools/disasm/files.txt
+++ b/tools/disasm/files.txt
@@ -284,6 +284,7 @@
             0x800980E0 : "guS2DInitBg",
             0x80098130 : "xldtob",
             0x80098160 : "vimgr",
+            0x80098180 : "voicecontrolgain",
 
             # .rodata section
             0x80098190 : "boot_main",