diff --git a/Machines/Atari2600/Atari2600.cpp b/Machines/Atari2600/Atari2600.cpp
index 118d451c2..3271da44b 100644
--- a/Machines/Atari2600/Atari2600.cpp
+++ b/Machines/Atari2600/Atari2600.cpp
@@ -283,57 +283,63 @@ void Machine::output_pixels(unsigned int count)
 {
 	while(count--)
 	{
-		// apply any queued changes and flush the record
-		if(_upcomingEvents[_upcomingEventsPointer].updates & Event::Action::HMoveSetup)
+		if(_upcomingEvents[_upcomingEventsPointer].updates)
 		{
-			_stateByTime = _stateByExtendTime[1];
-
-			// clear any ongoing moves
-			if(_hMoveFlags)
+			// apply any queued changes and flush the record
+			if(_upcomingEvents[_upcomingEventsPointer].updates & Event::Action::HMoveSetup)
 			{
-				for(int c = 0; c < number_of_upcoming_events; c++)
+				// schedule an extended left border
+				_stateByTime = _stateByExtendTime[1];
+
+				// clear any ongoing moves
+				if(_hMoveFlags)
 				{
-					_upcomingEvents[c].updates &= ~(Event::Action::HMoveCompare | Event::Action::HMoveDecrement);
+					for(int c = 0; c < number_of_upcoming_events; c++)
+					{
+						_upcomingEvents[c].updates &= ~(Event::Action::HMoveCompare | Event::Action::HMoveDecrement);
+					}
+				}
+
+				// schedule new moves
+				_hMoveFlags = 0x1f;
+				_hMoveCounter = 15;
+
+				// follow-through into a compare immediately
+				_upcomingEvents[_upcomingEventsPointer].updates |= Event::Action::HMoveCompare;
+			}
+
+			if(_upcomingEvents[_upcomingEventsPointer].updates & Event::Action::HMoveCompare)
+			{
+				for(int c = 0; c < 5; c++)
+				{
+					if(((_objectMotion[c] >> 4)^_hMoveCounter) == 7)
+					{
+						_hMoveFlags &= ~(1 << c);
+					}
+				}
+				if(_hMoveFlags)
+				{
+					if(_hMoveCounter) _hMoveCounter--;
+					_upcomingEvents[(_upcomingEventsPointer+4)%number_of_upcoming_events].updates |= Event::Action::HMoveCompare;
+					_upcomingEvents[(_upcomingEventsPointer+2)%number_of_upcoming_events].updates |= Event::Action::HMoveDecrement;
 				}
 			}
 
-			// schedule new moves
-			_hMoveFlags = 0x1f;
-			_hMoveCounter = 15;
-
-			// follow-through into a compare immediately
-			_upcomingEvents[_upcomingEventsPointer].updates |= Event::Action::HMoveCompare;
-		}
-
-		if(_upcomingEvents[_upcomingEventsPointer].updates & Event::Action::HMoveCompare)
-		{
-			for(int c = 0; c < 5; c++)
+			if(_upcomingEvents[_upcomingEventsPointer].updates & Event::Action::HMoveDecrement)
 			{
-				if(((_objectMotion[c] >> 4)^_hMoveCounter) == 7)
-				{
-					_hMoveFlags &= ~(1 << c);
-				}
+				update_timers(_hMoveFlags);
 			}
-			if(_hMoveFlags)
+
+			if(_upcomingEvents[_upcomingEventsPointer].updates & Event::Action::ResetCounter)
 			{
-				if(_hMoveCounter) _hMoveCounter--;
-				_upcomingEvents[(_upcomingEventsPointer+4)%number_of_upcoming_events].updates |= Event::Action::HMoveCompare;
-				_upcomingEvents[(_upcomingEventsPointer+2)%number_of_upcoming_events].updates |= Event::Action::HMoveDecrement;
+				_objectCounter[_objectCounterPointer][_upcomingEvents[_upcomingEventsPointer].counter].count = 0;
 			}
+
+			// zero out current update event
+			_upcomingEvents[_upcomingEventsPointer].updates = 0;
 		}
 
-		if(_upcomingEvents[_upcomingEventsPointer].updates & Event::Action::HMoveDecrement)
-		{
-			update_timers(_hMoveFlags);
-		}
-
-		if(_upcomingEvents[_upcomingEventsPointer].updates & Event::Action::ResetCounter)
-		{
-			_objectCounter[_objectCounterPointer][_upcomingEvents[_upcomingEventsPointer].counter].count = 0;
-		}
-
-		// zero out current update event, progress to next
-		_upcomingEvents[_upcomingEventsPointer].updates = 0;
+		//  progress to next event
 		_upcomingEventsPointer = (_upcomingEventsPointer + 1)%number_of_upcoming_events;
 
 		// determine which output state is currently active
@@ -392,6 +398,7 @@ void Machine::output_pixels(unsigned int count)
 		_horizontalTimer = (_horizontalTimer + 1) % horizontalTimerPeriod;
 		if(!_horizontalTimer)
 		{
+			// switch back to a normal length left border
 			_stateByTime = _stateByExtendTime[0];
 			set_ready_line(false);
 		}
diff --git a/Machines/Atari2600/Atari2600.hpp b/Machines/Atari2600/Atari2600.hpp
index c6c8e99a4..656cc844d 100644
--- a/Machines/Atari2600/Atari2600.hpp
+++ b/Machines/Atari2600/Atari2600.hpp
@@ -16,7 +16,7 @@
 
 namespace Atari2600 {
 
-const unsigned int number_of_upcoming_events = 16;
+const unsigned int number_of_upcoming_events = 6;
 const unsigned int number_of_recorded_counters = 7;
 
 class Speaker: public ::Outputs::Filter<Speaker> {
diff --git a/OSBindings/Mac/Clock Signal/Views/CSOpenGLView.m b/OSBindings/Mac/Clock Signal/Views/CSOpenGLView.m
index 08188405d..2645c368b 100644
--- a/OSBindings/Mac/Clock Signal/Views/CSOpenGLView.m	
+++ b/OSBindings/Mac/Clock Signal/Views/CSOpenGLView.m	
@@ -34,7 +34,9 @@
 	CGLPixelFormatObj cglPixelFormat = [[self pixelFormat] CGLPixelFormatObj];
 	CVDisplayLinkSetCurrentCGDisplayFromOpenGLContext(_displayLink, cglContext, cglPixelFormat);
 
-	_serialDispatchQueue = dispatch_queue_create("", DISPATCH_QUEUE_SERIAL);
+	// create a serial dispatch queue
+	_serialDispatchQueue = dispatch_queue_create("OpenGLView", DISPATCH_QUEUE_SERIAL);
+//	dispatch_set_target_queue(_serialDispatchQueue, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0));
 
 	// set the clear colour
 	[self.openGLContext makeCurrentContext];
@@ -63,20 +65,21 @@ static CVReturn DisplayLinkCallback(CVDisplayLinkRef displayLink, const CVTimeSt
 		BOOL didSkip = _hasSkipped;
 		dispatch_async(_serialDispatchQueue, ^{
 			[self.delegate openGLView:self didUpdateToTime:time didSkipPreviousUpdate:didSkip frequency:frequency];
-			[self drawViewOnlyIfDirty:YES];
 			OSAtomicTestAndClear(processingMask, &_updateIsOngoing);
 		});
 		_hasSkipped = NO;
+		NSLog(@"+");
 	}
 	else
 	{
 		_hasSkipped = YES;
+		NSLog(@"-");
 	}
 
 	// Draw the display only if a previous draw is not still ongoing. -drawViewOnlyIfDirty: is guaranteed
 	// to be safe to call concurrently with -openGLView:updateToTime: so there's no need to worry about
 	// the above interrupting the below or vice versa.
-	if(_hasSkipped && !OSAtomicTestAndSet(drawingMask, &_updateIsOngoing))
+	if(!OSAtomicTestAndSet(drawingMask, &_updateIsOngoing))
 	{
 		dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
 			[self drawViewOnlyIfDirty:YES];