diff --git a/Machines/Atari2600/Atari2600.cpp b/Machines/Atari2600/Atari2600.cpp
index 8b92ad490..9a9463b6f 100644
--- a/Machines/Atari2600/Atari2600.cpp
+++ b/Machines/Atari2600/Atari2600.cpp
@@ -24,20 +24,25 @@ Machine::Machine() :
 	_piaDataValue{0xff, 0xff},
 	_tiaInputValue{0xff, 0xff}
 {
-	_crt = new Outputs::CRT::CRT(228, 1, Outputs::CRT::DisplayType::NTSC60, 2);
-	_crt->set_composite_sampling_function(
-		"float composite_sample(vec2 coordinate, float phase)\n"
-		"{\n"
-			"vec2 c = texture(texID, coordinate).rg;"
-			"float y = 0.1 + c.x * 0.91071428571429;\n"
-			"float aOffset = 6.283185308 * (c.y - 3.0 / 16.0) * 1.14285714285714;\n"
-			"return y + step(0.03125, c.y) * 0.1 * cos((coordinate.x * 2.0 * 3.141592654) - aOffset);\n"
-		"}");
-	_crt->set_output_device(Outputs::CRT::Television);
 	memset(_collisions, 0xff, sizeof(_collisions));
 	set_reset_line(true);
 }
 
+void Machine::setup_output(float aspect_ratio)
+{
+	_crt = new Outputs::CRT::CRT(228, 1, Outputs::CRT::DisplayType::NTSC60, 2);
+	_crt->set_composite_sampling_function(
+		"float composite_sample(usampler2D texID, vec2 coordinate, vec2 iCoordinate, float phase, float amplitude)\n"
+		"{\n"
+			"return 0.9;"
+//			"vec2 c = vec2(1.0);"//vec2(texture(texID, coordinate).rg) / vec2(255.0);"
+//			"float y = 0.1 + c.x * 0.91071428571429;\n"
+//			"float aOffset = 6.283185308 * (c.y - 3.0 / 16.0) * 1.14285714285714;\n"
+//			"return y + step(0.03125, c.y) * 0.1 * cos((coordinate.x * 2.0 * 3.141592654) - aOffset);\n"
+		"}");
+	_crt->set_output_device(Outputs::CRT::Television);
+}
+
 Machine::~Machine()
 {
 	delete[] _rom;
diff --git a/Machines/Atari2600/Atari2600.hpp b/Machines/Atari2600/Atari2600.hpp
index c3b5d6209..e0b2653b1 100644
--- a/Machines/Atari2600/Atari2600.hpp
+++ b/Machines/Atari2600/Atari2600.hpp
@@ -30,6 +30,7 @@ class Machine: public CPU6502::Processor<Machine> {
 		void set_digital_input(Atari2600DigitalInput input, bool state);
 
 		Outputs::CRT::CRT *get_crt() { return _crt; }
+		void setup_output(float aspect_ratio);
 
 	private:
 		uint8_t *_rom, *_romPages[4], _ram[128];
diff --git a/OSBindings/Mac/Clock Signal/Wrappers/CSAtari2600.mm b/OSBindings/Mac/Clock Signal/Wrappers/CSAtari2600.mm
index 2fc2ca00a..74cc46b7f 100644
--- a/OSBindings/Mac/Clock Signal/Wrappers/CSAtari2600.mm	
+++ b/OSBindings/Mac/Clock Signal/Wrappers/CSAtari2600.mm	
@@ -43,8 +43,10 @@
 	[super crt:crt didEndFrame:frame didDetectVSync:didDetectVSync];
 }*/
 
-- (void)doRunForNumberOfCycles:(int)numberOfCycles {
-	_atari2600.run_for_cycles(numberOfCycles);
+- (void)runForNumberOfCycles:(int)numberOfCycles {
+	@synchronized(self) {
+		_atari2600.run_for_cycles(numberOfCycles);
+	}
 }
 
 - (void)drawViewForPixelSize:(CGSize)pixelSize onlyIfDirty:(BOOL)onlyIfDirty {
@@ -52,15 +54,27 @@
 }
 
 - (void)setROM:(NSData *)rom {
+	@synchronized(self) {
 		_atari2600.set_rom(rom.length, (const uint8_t *)rom.bytes);
+	}
 }
 
 - (void)setState:(BOOL)state forDigitalInput:(Atari2600DigitalInput)digitalInput {
+	@synchronized(self) {
 		_atari2600.set_digital_input(digitalInput, state ? true : false);
+	}
 }
 
 - (void)setResetLineEnabled:(BOOL)enabled {
+	@synchronized(self) {
 		_atari2600.set_reset_line(enabled ? true : false);
+	}
+}
+
+- (void)setupOutputWithAspectRatio:(float)aspectRatio {
+	@synchronized(self) {
+		_atari2600.setup_output(aspectRatio);
+	}
 }
 
 @end
diff --git a/OSBindings/Mac/Clock Signal/Wrappers/CSElectron.mm b/OSBindings/Mac/Clock Signal/Wrappers/CSElectron.mm
index 52607f738..fe03ee17a 100644
--- a/OSBindings/Mac/Clock Signal/Wrappers/CSElectron.mm	
+++ b/OSBindings/Mac/Clock Signal/Wrappers/CSElectron.mm	
@@ -60,7 +60,6 @@
 - (BOOL)setSpeakerDelegate:(Outputs::Speaker::Delegate *)delegate sampleRate:(int)sampleRate {
 	@synchronized(self) {
 		_electron.get_speaker()->set_output_rate(sampleRate, 256);
-//		_electron.get_speaker()->set_output_quality(47);
 		_electron.get_speaker()->set_delegate(delegate);
 		return YES;
 	}
diff --git a/Outputs/CRT/CRT.hpp b/Outputs/CRT/CRT.hpp
index 25c2482c9..ed4ca7fbd 100644
--- a/Outputs/CRT/CRT.hpp
+++ b/Outputs/CRT/CRT.hpp
@@ -202,9 +202,9 @@ class CRT {
 		/*!	Sets a function that will map from whatever data the machine provided to a composite signal.
 
 			@param shader A GLSL fragment including a function with the signature
-			`float composite_sample(vec2 coordinate, float phase)` that evaluates to the composite signal
-			level as a function of a source buffer sampling location and the provided colour carrier phase.
-			The shader may assume a uniform array of sampler2Ds named `buffers` provides access to all input data.
+			`float composite_sample(usampler2D texID, vec2 coordinate, vec2 iCoordinate, float phase, float amplitude)` 
+			that evaluates to the composite signal level as a function of a source buffer, sampling location, colour
+			carrier phase and amplitude.
 		*/
 		inline void set_composite_sampling_function(const char *shader)
 		{
diff --git a/Outputs/CRT/Internals/CRTOpenGL.cpp b/Outputs/CRT/Internals/CRTOpenGL.cpp
index f69ec2d08..a9afeb42e 100644
--- a/Outputs/CRT/Internals/CRTOpenGL.cpp
+++ b/Outputs/CRT/Internals/CRTOpenGL.cpp
@@ -861,7 +861,8 @@ std::unique_ptr<OpenGL::Shader> OpenGLOutputBuilder::prepare_output_shader(char
 
 void OpenGLOutputBuilder::prepare_rgb_output_shader()
 {
-	rgb_shader_program = prepare_output_shader(get_rgb_output_vertex_shader(), get_rgb_output_fragment_shader(), source_data_texture_unit);
+	if(_rgb_shader)
+		rgb_shader_program = prepare_output_shader(get_rgb_output_vertex_shader(), get_rgb_output_fragment_shader(), source_data_texture_unit);
 }
 
 void OpenGLOutputBuilder::prepare_composite_output_shader()