diff --git a/KompleteSynthesia/USBController.h b/KompleteSynthesia/USBController.h
index ed817ab..6a496cb 100644
--- a/KompleteSynthesia/USBController.h
+++ b/KompleteSynthesia/USBController.h
@@ -37,12 +37,13 @@ extern const uint32_t kPID_S88MK3;
 @property (nonatomic, assign) CGSize screenSize;
 @property (nonatomic, assign) unsigned int screenCount;
 @property (nonatomic, assign) BOOL connected;
+@property (nonatomic, assign) uint32_t deviceInterfaceEndpoint;
 
 
 + (NSString*)descriptionWithIOReturn:(IOReturn)code;
 
 - (id)initWithError:(NSError**)error;
-- (BOOL)bulkWriteData:(NSData*)data endpoint:(int)endpointNumber error:(NSError**)error;
+- (BOOL)bulkWriteData:(NSData*)data error:(NSError**)error;
 - (void)teardown;
 
 
diff --git a/KompleteSynthesia/USBController.m b/KompleteSynthesia/USBController.m
index 5efdac5..44f551a 100644
--- a/KompleteSynthesia/USBController.m
+++ b/KompleteSynthesia/USBController.m
@@ -34,6 +34,9 @@
 const uint32_t kPID_S61MK3 = 0x1720;    // FIXME: NO IDEA - THESE ARE PLACEHOLDERS SO FAR
 const uint32_t kPID_S88MK3 = 0x1730;    // FIXME: NO IDEA - THESE ARE PLACEHOLDERS SO FAR
 
+const uint32_t kUSBDeviceInterface = 0x03;          // FIXME: Possibly MK2 specific.
+const uint32_t kUSBDeviceInterfaceEndpoint = 0x03;  // FIXME: Possibly MK2 specific.
+
 @implementation USBController {
     IOUSBDeviceInterface942** device;
     IOUSBInterfaceInterface942** interface;
@@ -53,6 +56,7 @@ - (id)initWithError:(NSError**)error
     self = [super init];
     if (self) {
         _connected = NO;
+        _deviceInterfaceEndpoint = kUSBDeviceInterfaceEndpoint;
         //transferActive = 0;
         if ([self detectDevice:error] == NULL) {
             return nil;
@@ -267,11 +271,11 @@ - (BOOL)endpoint:(uint8_t)ep pipeRef:(uint8_t*)pipep
     return NO;
 }
 
-- (BOOL)bulkWriteData:(NSData*)data endpoint:(int)endpointNumber error:(NSError**)error
+- (BOOL)bulkWriteData:(NSData*)data error:(NSError**)error
 {
     assert(data.length > 0);
     uint8_t pipeRef;
-    if ([self endpoint:endpointNumber pipeRef:&pipeRef] == NO) {
+    if ([self endpoint:_deviceInterfaceEndpoint pipeRef:&pipeRef] == NO) {
         NSLog(@"endpoint doesnt exist");
         if (error) {
             NSDictionary *userInfo = @{
@@ -355,7 +359,7 @@ - (IOUSBDeviceInterface942**)detectDevice:(NSError**)error
 
     io_registry_entry_t entry = 0;
 
-    entry = IORegistryGetRootEntry(kIOMasterPortDefault);
+    entry = IORegistryGetRootEntry(kIOMainPortDefault);
     if (entry == 0) {
         return nil;
     }
@@ -480,7 +484,7 @@ - (BOOL)openDevice:(NSError**)error
         return NO;
     }
     
-    ret = [self openDeviceInterface:3];
+    ret = [self openDeviceInterface:kUSBDeviceInterface];
     if (ret != kIOReturnSuccess) {
         if (error) {
             NSDictionary *userInfo = @{
diff --git a/KompleteSynthesia/VideoController.m b/KompleteSynthesia/VideoController.m
index 09ecc9b..c45efb3 100644
--- a/KompleteSynthesia/VideoController.m
+++ b/KompleteSynthesia/VideoController.m
@@ -287,7 +287,7 @@ - (BOOL)drawNIImage:(NIImage*)image screen:(uint8_t)screen x:(unsigned int)x y:(
     const unsigned char commandBlob3[] = { 0x02, 0x00, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00 };
     [stream appendBytes:commandBlob3 length:sizeof(commandBlob3)];
 
-    BOOL ret = [usb bulkWriteData:stream endpoint:3 error:error];
+    BOOL ret = [usb bulkWriteData:stream error:error];
 
     stream.length = 0;