diff --git a/include/os.h b/include/os.h
index 904d78a29f..838d8234ac 100644
--- a/include/os.h
+++ b/include/os.h
@@ -54,8 +54,8 @@ typedef struct {
 } __OSTranxInfo; // size = 0x60
 
 
-typedef struct OSPiHandle_s {
-    /* 0x00 */ struct OSPiHandle_s* next;
+typedef struct OSPiHandle {
+    /* 0x00 */ struct OSPiHandle* next;
     /* 0x04 */ u8 type;
     /* 0x05 */ u8 latency;
     /* 0x06 */ u8 pageSize;
diff --git a/include/variables.h b/include/variables.h
index af0f323d9c..a4bf58d264 100644
--- a/include/variables.h
+++ b/include/variables.h
@@ -85,7 +85,7 @@ extern OSViMode osViModeMpalLan1;
 // extern __OSViContext D_80098060[2];
 extern __OSViContext* __osViCurr;
 extern __OSViContext* __osViNext;
-// extern UNK_TYPE4 D_800980D0;
+// extern UNK_TYPE4 sCartRomNeedsInit;
 extern OSViMode osViModeFpalLan1;
 // extern u8 ldigs[];
 // extern u8 udigs[];
diff --git a/spec b/spec
index d8a68f89c1..7e17eeefd7 100644
--- a/spec
+++ b/spec
@@ -195,8 +195,6 @@ beginseg
     include "build/src/libultra/io/pfsisplug.o"
     include "build/src/libultra/voice/voicegetstatus.o"
     include "build/src/libultra/io/cartrominit.o"
-    include "build/data/boot/cartrominit.data.o"
-    include "build/data/boot/cartrominit.bss.o"
     include "build/src/libultra/gu/guS2DInitBg.o"
     include "build/data/boot/guS2DInitBg.data.o"
     include "build/src/libultra/io/pfsselectbank.o"
diff --git a/src/libultra/io/cartrominit.c b/src/libultra/io/cartrominit.c
index 6b96905c74..0825b472cb 100644
--- a/src/libultra/io/cartrominit.c
+++ b/src/libultra/io/cartrominit.c
@@ -1,3 +1,63 @@
 #include "global.h"
 
-#pragma GLOBAL_ASM("asm/non_matchings/boot/cartrominit/osCartRomInit.s")
+OSPiHandle CartRomHandle;
+
+OSPiHandle* osCartRomInit(void) {
+    register u32 initialConfig;
+    register s32 status;
+    register u32 prevInt;
+    register u32 lastLatency;
+    register u32 lastPageSize;
+    register u32 lastRelDuration;
+    register u32 lastPulse;
+
+    static s32 sCartRomNeedsInit = true;
+
+    __osPiGetAccess();
+
+    if (!sCartRomNeedsInit) {
+        __osPiRelAccess();
+        return &CartRomHandle;
+    }
+
+    sCartRomNeedsInit = false;
+    CartRomHandle.type = DEVICE_TYPE_CART;
+    CartRomHandle.baseAddress = 0xB0000000;
+    CartRomHandle.domain = 0;
+    CartRomHandle.speed = 0;
+    bzero(&CartRomHandle.transferInfo, sizeof(__OSTranxInfo));
+
+    /* Uses `status & PI_STATUS_ERROR` in OoT */
+    while (status = HW_REG(PI_STATUS_REG, u32), status & (PI_STATUS_BUSY | PI_STATUS_IOBUSY)) {
+        ;
+    }
+
+    lastLatency = HW_REG(PI_BSD_DOM1_LAT_REG, u32);
+    lastPageSize = HW_REG(PI_BSD_DOM1_PGS_REG, u32);
+    lastRelDuration = HW_REG(PI_BSD_DOM1_RLS_REG, u32);
+    lastPulse = HW_REG(PI_BSD_DOM1_PWD_REG, u32);
+
+    HW_REG(PI_BSD_DOM1_LAT_REG, u32) = 0xFF;
+    HW_REG(PI_BSD_DOM1_PGS_REG, u32) = 0;
+    HW_REG(PI_BSD_DOM1_RLS_REG, u32) = 3;
+    HW_REG(PI_BSD_DOM1_PWD_REG, u32) = 0xFF;
+
+    initialConfig = HW_REG(CartRomHandle.baseAddress, u32);
+    CartRomHandle.latency = initialConfig & 0xFF;
+    CartRomHandle.pageSize = (initialConfig >> 0x10) & 0xF;
+    CartRomHandle.relDuration = (initialConfig >> 0x14) & 0xF;
+    CartRomHandle.pulse = (initialConfig >> 8) & 0xFF;
+
+    HW_REG(PI_BSD_DOM1_LAT_REG, u32) = lastLatency;
+    HW_REG(PI_BSD_DOM1_PGS_REG, u32) = lastPageSize;
+    HW_REG(PI_BSD_DOM1_RLS_REG, u32) = lastRelDuration;
+    HW_REG(PI_BSD_DOM1_PWD_REG, u32) = lastPulse;
+
+    prevInt = __osDisableInt();
+    CartRomHandle.next = __osPiTable;
+    __osPiTable = &CartRomHandle;
+    __osRestoreInt(prevInt);
+    __osPiRelAccess();
+
+    return &CartRomHandle;
+}
diff --git a/tools/disasm/variables.txt b/tools/disasm/variables.txt
index b633dd2922..35716f88b2 100644
--- a/tools/disasm/variables.txt
+++ b/tools/disasm/variables.txt
@@ -78,7 +78,7 @@
     0x80098060:("D_80098060","__OSViContext","[2]",0x60),
     0x800980C0:("__osViCurr","__OSViContext*","",0x4),
     0x800980C4:("__osViNext","__OSViContext*","",0x4),
-    0x800980D0:("D_800980D0","UNK_TYPE4","",0x4),
+    0x800980D0:("sCartRomNeedsInit","UNK_TYPE4","",0x4),
     0x800980E0:("osViModeFpalLan1","OSViMode","",0x50),
     0x80098130:("ldigs","u8","[]",0x14),
     0x80098144:("udigs","u8","[]",0x14),