diff --git a/include/dolphin/GBAPriv.h b/include/dolphin/GBAPriv.h
index 24295e57..355d163c 100644
--- a/include/dolphin/GBAPriv.h
+++ b/include/dolphin/GBAPriv.h
@@ -9,6 +9,9 @@
 #ifdef __cplusplus
 extern "C" {
 #endif
+
+typedef void (*GBATransferCallback)(s32 chan);
+
 typedef struct GBASecParams {
   u8 data[0x40];
 } GBASecParams;
@@ -28,7 +31,7 @@ typedef struct GBA {
   s32 result;
   OSThreadQueue thread_queue;
   OSTime delay;
-  GBACallback _38;
+  GBATransferCallback _38;
   s32 _3c;
   s32 palette_color;
   s32 palette_speed;
@@ -43,14 +46,14 @@ typedef struct GBA {
   char data4[0x100u - 0xfcu];
 } GBA;
 
-
 extern GBA __GBA[4];
 extern BOOL __GBAReset;
 
-//void __GBAHandler(s32 chan, s32 ret);
+// void __GBAHandler(s32 chan, s32 ret);
 void __GBASyncCallback(s32 chan, s32 ret);
 s32 __GBASync(s32 chan);
 OSTime __GBASetDelay(s32 chan, OSTime delay);
+s32 __GBATransfer(s32 chan, s32 w1, s32 w2, GBATransferCallback callback);
 
 #ifdef __cplusplus
 }
diff --git a/include/dolphin/os/OSContext.h b/include/dolphin/os/OSContext.h
index acca3026..0c94c06c 100644
--- a/include/dolphin/os/OSContext.h
+++ b/include/dolphin/os/OSContext.h
@@ -33,6 +33,7 @@ typedef struct OSContext {
 
 void OSSaveContext(OSContext* context);
 void OSClearContext(OSContext* context);
+OSContext* OSGetCurrentContext();
 void OSSetCurrentContext(OSContext* context);
 
 #ifdef __cplusplus
diff --git a/src/Dolphin/GBA/GBA.c b/src/Dolphin/GBA/GBA.c
index 8b75c2e1..908f5d56 100644
--- a/src/Dolphin/GBA/GBA.c
+++ b/src/Dolphin/GBA/GBA.c
@@ -11,7 +11,7 @@ static OSResetFunctionInfo ResetFunctionInfo = {
   127
 };
 
-void ShortCommandProc(s32 chan, s32 ret) {
+void ShortCommandProc(s32 chan) {
   GBA* gba;
   gba = &__GBA[chan];
 
diff --git a/src/Dolphin/GBA/GBARead.c b/src/Dolphin/GBA/GBARead.c
index 4f0b2a5d..3fc58b8e 100644
--- a/src/Dolphin/GBA/GBARead.c
+++ b/src/Dolphin/GBA/GBARead.c
@@ -1,6 +1,6 @@
 #include "dolphin/GBAPriv.h"
 
-void ReadProc(s32 chan, s32 ret) {
+void ReadProc(s32 chan) {
   GBA* gba;
   gba = &__GBA[chan];
 
diff --git a/src/Dolphin/GBA/GBAWrite.c b/src/Dolphin/GBA/GBAWrite.c
index 7c910cf0..3e5ad95d 100644
--- a/src/Dolphin/GBA/GBAWrite.c
+++ b/src/Dolphin/GBA/GBAWrite.c
@@ -1,6 +1,6 @@
 #include "dolphin/GBAPriv.h"
 
-void WriteProc(s32 chan, s32 ret) {
+void WriteProc(s32 chan) {
   GBA* gba;
   gba = &__GBA[chan];
 
diff --git a/src/Dolphin/GBA/GBAXfer.c b/src/Dolphin/GBA/GBAXfer.c
index 18736cc4..59a25c12 100644
--- a/src/Dolphin/GBA/GBAXfer.c
+++ b/src/Dolphin/GBA/GBAXfer.c
@@ -1,17 +1,47 @@
 #include "dolphin/GBAPriv.h"
 #include "dolphin/sipriv.h"
 
-void __GBAHandler() {
-  
+void __GBAHandler(s32 chan, u32 sr, OSContext* context) {
+  int tmp;
+  GBA* gba;
+  OSContext tmpCtx;
+  GBACallback callback;
+  GBATransferCallback xferCallback;
+  gba = &__GBA[chan];
+  if (__GBAReset != 0) {
+    return;
+  }
+
+  if ((sr & 0xf)) {
+    gba->result = 1;
+  } else {
+    gba->result = 0;
+  }
+
+  if (gba->_38 != NULL) {
+    xferCallback = gba->_38;
+    gba->_38 = NULL;
+    xferCallback(chan);
+  }
+
+  if (gba->callback == NULL) {
+    return;
+  }
+
+  OSClearContext(&tmpCtx);
+  OSSetCurrentContext(&tmpCtx);
+  callback = gba->callback;
+  gba->callback = NULL;
+  callback(chan, gba->result);
+  OSClearContext(&tmpCtx);
+  OSSetCurrentContext(context);
 }
 
-void __GBASyncCallback(s32 chan, s32 ret) {
-  OSWakeupThread(&__GBA[chan].thread_queue);
-}
+void __GBASyncCallback(s32 chan, s32 ret) { OSWakeupThread(&__GBA[chan].thread_queue); }
 
 s32 __GBASync(s32 chan) {
   GBA* gba;
-  s32 enabled;  
+  s32 enabled;
   s32 ret;
   gba = &__GBA[chan];
 
@@ -27,10 +57,46 @@ s32 __GBASync(s32 chan) {
 }
 
 void TypeAndStatusCallback(s32 chan, u32 type) {
+  s32 tmp;
+  GBA* gba;
+  OSContext* context;
+  GBACallback callback;
+  GBATransferCallback xferCallback;
+  OSContext tmpContext;
+  gba = &__GBA[chan];
+  if (__GBAReset != 0) {
+    return;
+  }
 
+  if ((type & 0xFF) != 0 || (type & 0xffff0000) != 0x40000) {
+    gba->result = 1;
+  } else {
+    if (SITransfer(chan, &gba->command, gba->_0c, gba->dst, gba->_10, __GBAHandler, gba->delay)) {
+      return;
+    }
+    gba->result = 2;
+  }
+
+  if (gba->_38 != NULL) {
+    xferCallback = gba->_38;
+    gba->_38 = NULL;
+    xferCallback(chan);
+  }
+
+  if (gba->callback != NULL) {
+    context = OSGetCurrentContext();
+    OSClearContext(&tmpContext);
+    OSSetCurrentContext(&tmpContext);
+    callback = gba->callback;
+    gba->callback = NULL;
+    callback(chan, gba->result);
+    OSClearContext(&tmpContext);
+    OSSetCurrentContext(context);
+    __OSReschedule();
+  }
 }
 
-s32 __GBATransfer(s32 chan, s32 w1, s32 w2, GBACallback callback) {
+s32 __GBATransfer(s32 chan, s32 w1, s32 w2, GBATransferCallback callback) {
   s32 enabled;
   GBA* gba;
   gba = &__GBA[chan];