diff --git a/Machines/Electron/Electron.cpp b/Machines/Electron/Electron.cpp
index 29fbbb90e..7d82e8e30 100644
--- a/Machines/Electron/Electron.cpp
+++ b/Machines/Electron/Electron.cpp
@@ -64,6 +64,7 @@ void Machine::setup_output()
 			"uint texValue = texture(sampler, coordinate).r;"
 			"texValue >>= 4 - (int(icoordinate.x * 2) & 1)*4;"
 			"return vec4(texValue & 4u, texValue & 2u, texValue & 1u, 1.0);"
+//			"return vec4(1.0);"
 		"}");
 	_crt->set_output_device(Outputs::CRT::Monitor);
 
diff --git a/Outputs/CRT/CRT.cpp b/Outputs/CRT/CRT.cpp
index b3407d69e..d7bf891c0 100644
--- a/Outputs/CRT/CRT.cpp
+++ b/Outputs/CRT/CRT.cpp
@@ -132,7 +132,7 @@ void CRT::advance_cycles(unsigned int number_of_cycles, unsigned int source_divi
 		uint8_t *next_run = nullptr;
 		if(is_output_segment)
 		{
-			next_run = _openGL_output_builder->get_next_output_run();
+			next_run = (_openGL_output_builder->get_output_device() == Monitor) ? _openGL_output_builder->get_next_output_run() : _openGL_output_builder->get_next_source_run();
 		}
 
 		//	Vertex output is arranged for triangle strips, as:
@@ -195,18 +195,22 @@ void CRT::advance_cycles(unsigned int number_of_cycles, unsigned int source_divi
 				output_position_y(3) = output_position_y(4) = output_position_y(5) = (uint16_t)(_vertical_flywheel->get_current_output_position() / _vertical_flywheel_output_divider);
 				output_timestamp(3) = output_timestamp(4) = output_timestamp(5) = _openGL_output_builder->get_current_field_time();
 				output_tex_x(3) = output_tex_x(4) = output_tex_x(5) = tex_x;
+
+				_openGL_output_builder->complete_output_run(6);
 			}
 			else
 			{
 				source_input_position_x(1) = tex_x;
 				source_output_position_x(1) = (uint16_t)_horizontal_flywheel->get_current_output_position();
+
+				_openGL_output_builder->complete_source_run();
 			}
 		}
 
-		if(is_output_segment)
-		{
-			_openGL_output_builder->complete_output_run();
-		}
+//		if(is_output_segment)
+//		{
+//			_openGL_output_builder->complete_output_run(6);
+//		}
 
 		// if this is horizontal retrace then advance the output line counter and bookend an output run
 		if(_openGL_output_builder->get_output_device() == Television)
@@ -230,8 +234,9 @@ void CRT::advance_cycles(unsigned int number_of_cycles, unsigned int source_divi
 				output_lateral(0) = 0;
 				output_lateral(1) = _is_writing_composite_run ? 1 : 0;
 				output_lateral(2) = 1;
+				output_frame_id(0) = output_frame_id(1) = output_frame_id(2) = (uint8_t)_openGL_output_builder->get_current_field();
 
-				_openGL_output_builder->complete_output_run();
+				_openGL_output_builder->complete_output_run(3);
 				_is_writing_composite_run ^= true;
 			}
 
diff --git a/Outputs/CRT/Internals/CRTConstants.hpp b/Outputs/CRT/Internals/CRTConstants.hpp
index c82540243..d14e7aee5 100644
--- a/Outputs/CRT/Internals/CRTConstants.hpp
+++ b/Outputs/CRT/Internals/CRTConstants.hpp
@@ -43,7 +43,7 @@ const int IntermediateBufferWidth = 2048;
 const int IntermediateBufferHeight = 2048;
 
 // Some internal
-const GLsizeiptr InputVertexBufferDataSize = 262080;	// a multiple of 6 * OutputVertexSize
+const GLsizeiptr OutputVertexBufferDataSize = 262080;	// a multiple of 6 * OutputVertexSize
 
 
 // Runs are divided discretely by vertical syncs in order to put a usable bounds on the uniform used to track
diff --git a/Outputs/CRT/Internals/CRTOpenGL.cpp b/Outputs/CRT/Internals/CRTOpenGL.cpp
index 0afd28d18..acd334fc5 100644
--- a/Outputs/CRT/Internals/CRTOpenGL.cpp
+++ b/Outputs/CRT/Internals/CRTOpenGL.cpp
@@ -112,7 +112,7 @@ void OpenGLOutputBuilder::draw_frame(unsigned int output_width, unsigned int out
 
 		glBindBuffer(GL_ARRAY_BUFFER, output_array_buffer);
 
-		glBufferData(GL_ARRAY_BUFFER, InputVertexBufferDataSize, NULL, GL_STREAM_DRAW);
+		glBufferData(GL_ARRAY_BUFFER, OutputVertexBufferDataSize, NULL, GL_STREAM_DRAW);
 		_output_buffer_data_pointer = 0;
 
 		glBindVertexArray(output_vertex_array);
@@ -216,7 +216,7 @@ void OpenGLOutputBuilder::draw_frame(unsigned int output_width, unsigned int out
 		{
 			// draw
 			GLsizei primitive_count = (GLsizei)(count / OutputVertexSize);
-			GLsizei max_count = (GLsizei)((InputVertexBufferDataSize - start) / OutputVertexSize);
+			GLsizei max_count = (GLsizei)((OutputVertexBufferDataSize - start) / OutputVertexSize);
 			if(primitive_count < max_count)
 			{
 				glDrawArrays(GL_TRIANGLE_STRIP, (GLint)(start / OutputVertexSize), primitive_count);
@@ -231,7 +231,7 @@ void OpenGLOutputBuilder::draw_frame(unsigned int output_width, unsigned int out
 
 	// drawing commands having been issued, reclaim the array buffer pointer
 //	_buffer_builder->move_to_new_line();
-	_output_buffer_data = (uint8_t *)glMapBufferRange(GL_ARRAY_BUFFER, 0, InputVertexBufferDataSize, GL_MAP_WRITE_BIT | GL_MAP_UNSYNCHRONIZED_BIT);
+	_output_buffer_data = (uint8_t *)glMapBufferRange(GL_ARRAY_BUFFER, 0, OutputVertexBufferDataSize, GL_MAP_WRITE_BIT | GL_MAP_UNSYNCHRONIZED_BIT);
 	_input_texture_data = (uint8_t *)glMapBufferRange(GL_PIXEL_UNPACK_BUFFER, 0, _input_texture_array_size, GL_MAP_WRITE_BIT | GL_MAP_UNSYNCHRONIZED_BIT);
 	_output_mutex->unlock();
 }
diff --git a/Outputs/CRT/Internals/CRTOpenGL.hpp b/Outputs/CRT/Internals/CRTOpenGL.hpp
index a2086d4f8..1144bd4ea 100644
--- a/Outputs/CRT/Internals/CRTOpenGL.hpp
+++ b/Outputs/CRT/Internals/CRTOpenGL.hpp
@@ -117,13 +117,13 @@ class OpenGLOutputBuilder {
 		{
 			_output_mutex->lock();
 			uint8_t *pointer = &_output_buffer_data[_output_buffer_data_pointer];
-			_output_buffer_data_pointer = (_output_buffer_data_pointer + 6 * OutputVertexSize) % InputVertexBufferDataSize;
 			return pointer;
 		}
 
-		inline void complete_output_run()
+		inline void complete_output_run(size_t vertices_written)
 		{
-			_run_builders[_run_write_pointer]->amount_of_data += 6 * OutputVertexSize;
+			_run_builders[_run_write_pointer]->amount_of_data += vertices_written * OutputVertexSize;
+			_output_buffer_data_pointer = (_output_buffer_data_pointer + vertices_written * OutputVertexSize) % OutputVertexBufferDataSize;
 			_output_mutex->unlock();
 		}