diff --git a/Machines/Apple/Macintosh/Macintosh.cpp b/Machines/Apple/Macintosh/Macintosh.cpp
index 5b05f049e..d8e966024 100644
--- a/Machines/Apple/Macintosh/Macintosh.cpp
+++ b/Machines/Apple/Macintosh/Macintosh.cpp
@@ -40,7 +40,7 @@ class ConcreteMachine:
 		 	mc68000_(*this),
 		 	video_(ram_.data()),
 		 	via_(via_port_handler_),
-		 	via_port_handler_(*this, clock_, keyboard_),
+		 	via_port_handler_(*this, clock_, keyboard_, video_),
 		 	iwm_(CLOCK_RATE) {
 
 			// Grab a copy of the ROM and convert it into big-endian data.
@@ -70,7 +70,7 @@ class ConcreteMachine:
 		using Microcycle = CPU::MC68000::Microcycle;
 
 		HalfCycles perform_bus_operation(const Microcycle &cycle, int is_supervisor) {
-			time_since_video_update_ += cycle.length;
+//			time_since_video_update_ += cycle.length;
 			time_since_iwm_update_ += cycle.length;
 
 			// The VIA runs at one-tenth of the 68000's clock speed, in sync with the E clock.
@@ -100,6 +100,10 @@ class ConcreteMachine:
 				via_.set_control_line_input(MOS::MOS6522::Port::A, MOS::MOS6522::Line::Two, false);
 			}
 
+			// Update the video. TODO: only on demand.
+			video_.run_for(cycle.length);
+			via_.set_control_line_input(MOS::MOS6522::Port::A, MOS::MOS6522::Line::One, video_.vsync());
+
 			// Update interrupt input. TODO: move this into a VIA/etc delegate callback?
 			mc68000_.set_interrupt_level( (via_.get_interrupt_line() ? 1 : 0) );
 
@@ -140,7 +144,8 @@ class ConcreteMachine:
 
 							default:
 								if(cycle.operation & Microcycle::Read) {
-									cycle.value->halves.low = 0xff;
+									printf("Unrecognised read %06x\n", *cycle.address & 0xffffff);
+									cycle.value->halves.low = 0x00;
 									if(cycle.operation & Microcycle::SelectWord) cycle.value->halves.high = 0xff;
 								}
 							break;
@@ -211,7 +216,7 @@ class ConcreteMachine:
 		}
 
 		void flush() {
-			video_.run_for(time_since_video_update_.flush());
+//			video_.run_for(time_since_video_update_.flush());
 		}
 
 		void set_rom_is_overlay(bool rom_is_overlay) {
@@ -225,8 +230,8 @@ class ConcreteMachine:
 	private:
 		class VIAPortHandler: public MOS::MOS6522::PortHandler {
 			public:
-				VIAPortHandler(ConcreteMachine &machine, RealTimeClock &clock, Keyboard &keyboard) :
-					machine_(machine), clock_(clock), keyboard_(keyboard) {}
+				VIAPortHandler(ConcreteMachine &machine, RealTimeClock &clock, Keyboard &keyboard, Video &video) :
+					machine_(machine), clock_(clock), keyboard_(keyboard), video_(video) {}
 
 				using Port = MOS::MOS6522::Port;
 				using Line = MOS::MOS6522::Line;
@@ -275,11 +280,13 @@ class ConcreteMachine:
 					switch(port) {
 						case Port::A:
 //							printf("6522 r A\n");
-						return 0xff;
+						return 0x00;	// TODO: b7 = SCC wait/request
 
 						case Port::B:
-//							printf("6522 r B\n");
-						return (clock_.get_data() ? 0x02 : 0x00);
+						return
+							(clock_.get_data() ? 0x02 : 0x00) |
+							(video_.is_outputting() ? 0x00 : 0x40);
+							// TODO: mouse button, y2, x2
 					}
 				}
 
@@ -299,6 +306,7 @@ class ConcreteMachine:
 				ConcreteMachine &machine_;
 				RealTimeClock &clock_;
 				Keyboard &keyboard_;
+				Video &video_;
 		};
 
 		std::array<uint16_t, 32*1024> rom_;
@@ -318,7 +326,8 @@ class ConcreteMachine:
  		HalfCycles via_clock_;
  		HalfCycles real_time_clock_;
  		HalfCycles keyboard_clock_;
- 		HalfCycles time_since_video_update_;
+ 		HalfCycles video_clock_;
+// 		HalfCycles time_since_video_update_;
  		HalfCycles time_since_iwm_update_;
 
 		bool ROM_is_overlay_ = true;
diff --git a/Machines/Apple/Macintosh/Video.cpp b/Machines/Apple/Macintosh/Video.cpp
index 72e4ca94b..1028003a9 100644
--- a/Machines/Apple/Macintosh/Video.cpp
+++ b/Machines/Apple/Macintosh/Video.cpp
@@ -17,6 +17,8 @@ namespace {
 const HalfCycles line_length(704);
 const int number_of_lines = 370;
 const HalfCycles frame_length(line_length * HalfCycles(number_of_lines));
+const int sync_start = 36;
+const int sync_end = 38;
 
 }
 
@@ -44,8 +46,6 @@ void Video::set_scan_target(Outputs::Display::ScanTarget *scan_target) {
 }
 
 void Video::run_for(HalfCycles duration) {
-	const int sync_start = 36;
-	const int sync_end = 38;
 
 	// The number of HalfCycles is literally the number of pixel clocks to move through,
 	// since pixel output occurs at twice the processor clock. So divide by 16 to get
@@ -145,6 +145,18 @@ void Video::run_for(HalfCycles duration) {
 	}
 }
 
+bool Video::vsync() {
+	const int line = (frame_position_ / line_length).as_int();
+	return line >= 353 && line < 356;
+}
+
+bool Video::is_outputting() {
+	const int column = (frame_position_ % line_length).as_int() >> 4;
+	const int line = (frame_position_ / line_length).as_int();
+	return line < 342 && column < 32;
+}
+
 void Video::set_use_alternate_screen_buffer(bool use_alternate_screen_buffer) {
 	use_alternate_screen_buffer_ = use_alternate_screen_buffer;
 }
+
diff --git a/Machines/Apple/Macintosh/Video.hpp b/Machines/Apple/Macintosh/Video.hpp
index 5457bc1ff..041ffba13 100644
--- a/Machines/Apple/Macintosh/Video.hpp
+++ b/Machines/Apple/Macintosh/Video.hpp
@@ -23,6 +23,8 @@ class Video {
 		void set_use_alternate_screen_buffer(bool use_alternate_screen_buffer);
 
 		// TODO: feedback on blanks and syncs.
+		bool vsync();
+		bool is_outputting();
 
 	private:
 		Outputs::CRT::CRT crt_;