diff --git a/Machines/Electron/Electron.cpp b/Machines/Electron/Electron.cpp
index 0e51c89bf..16ccfa9a1 100644
--- a/Machines/Electron/Electron.cpp
+++ b/Machines/Electron/Electron.cpp
@@ -67,6 +67,7 @@ void Machine::setup_output()
 //			"return vec4(1.0);"
 		"}");
 	_crt->set_output_device(Outputs::CRT::Monitor);
+	_crt->set_visible_area(_crt->get_rect_for_area(first_graphics_line - 3, 256, first_graphics_cycle * crt_cycles_multiplier, 80 * crt_cycles_multiplier, 4.0f / 3.0f));
 
 	// The maximum output frequency is 62500Hz and all other permitted output frequencies are integral divisions of that;
 	// however setting the speaker on or off can happen on any 2Mhz cycle, and probably (?) takes effect immediately. So
diff --git a/OSBindings/Mac/Clock Signal/Documents/Atari2600Document.swift b/OSBindings/Mac/Clock Signal/Documents/Atari2600Document.swift
index c9b385399..8e42b1186 100644
--- a/OSBindings/Mac/Clock Signal/Documents/Atari2600Document.swift	
+++ b/OSBindings/Mac/Clock Signal/Documents/Atari2600Document.swift	
@@ -19,7 +19,6 @@ class Atari2600Document: MachineDocument {
 	override func windowControllerDidLoadNib(aController: NSWindowController) {
 		super.windowControllerDidLoadNib(aController)
 		atari2600.view = openGLView
-//		openGLView.frameBounds = CGRectMake(0.1, 0.1, 0.8, 0.8)
 	}
 
 	override class func autosavesInPlace() -> Bool {
diff --git a/Outputs/CRT/CRT.cpp b/Outputs/CRT/CRT.cpp
index 86c909722..d5c99866c 100644
--- a/Outputs/CRT/CRT.cpp
+++ b/Outputs/CRT/CRT.cpp
@@ -357,3 +357,41 @@ void CRT::output_data(unsigned int number_of_cycles, unsigned int source_divider
 	};
 	output_scan(&scan);
 }
+
+Outputs::CRT::Rect CRT::get_rect_for_area(int first_line_after_sync, int number_of_lines, int first_cycle_after_sync, int number_of_cycles, float aspect_ratio)
+{
+	first_cycle_after_sync *= _time_multiplier;
+	number_of_cycles *= _time_multiplier;
+
+	// determine prima facie x extent
+	unsigned int horizontal_period = _horizontal_flywheel->get_standard_period();
+	unsigned int horizontal_scan_period = _horizontal_flywheel->get_scan_period();
+	unsigned int horizontal_retrace_period = horizontal_period - horizontal_scan_period;
+
+	float start_x = (float)((unsigned)first_cycle_after_sync - horizontal_retrace_period) / (float)horizontal_scan_period;
+	float width = (float)number_of_cycles / (float)horizontal_scan_period;
+
+	// determine prima facie y extent
+	unsigned int vertical_period = _vertical_flywheel->get_standard_period();
+	unsigned int vertical_scan_period = _vertical_flywheel->get_scan_period();
+	unsigned int vertical_retrace_period = vertical_period - vertical_scan_period;
+	float start_y = (float)(((unsigned)first_line_after_sync * horizontal_period) - vertical_retrace_period) / (float)vertical_scan_period;
+	float height = (float)((unsigned)number_of_lines * horizontal_period) / vertical_scan_period;
+
+	// adjust to ensure aspect ratio is correct
+	float adjusted_aspect_ratio = (3.0f*aspect_ratio / 4.0f);
+	float ideal_width = height * adjusted_aspect_ratio;
+	if(ideal_width > width)
+	{
+		start_x -= (ideal_width - width) * 0.5f;
+		width = ideal_width;
+	}
+	else
+	{
+		float ideal_height = width / adjusted_aspect_ratio;
+		start_y -= (ideal_height - height) * 0.5f;
+		height = ideal_height;
+	}
+
+	return Rect(start_x, start_y, width, height);
+}
diff --git a/Outputs/CRT/CRT.hpp b/Outputs/CRT/CRT.hpp
index 5303fbe6c..2f2dadc26 100644
--- a/Outputs/CRT/CRT.hpp
+++ b/Outputs/CRT/CRT.hpp
@@ -247,6 +247,8 @@ class CRT {
 		{
 			_openGL_output_builder->set_visible_area(visible_area);
 		}
+
+		Rect get_rect_for_area(int first_line_after_sync, int number_of_lines, int first_cycle_after_sync, int number_of_cycles, float aspect_ratio);
 };
 
 }
diff --git a/Outputs/CRT/CRTTypes.hpp b/Outputs/CRT/CRTTypes.hpp
index 262f01616..842c2f9f3 100644
--- a/Outputs/CRT/CRTTypes.hpp
+++ b/Outputs/CRT/CRTTypes.hpp
@@ -23,7 +23,7 @@ struct Rect {
 
 	Rect() {}
 	Rect(float x, float y, float width, float height) :
-		origin({.x = x, .y = y}), size({.width = width, .height =height}) {}
+		origin({.x = x, .y = y}), size({.width = width, .height = height}) {}
 };
 
 enum DisplayType {