Puts the disk controller back into the loop with knowledge about reading mode, and uses that knowledge to cut off the PLL.

Components/1770/1770.cpp

@@ -541,7 +541,7 @@ void WD1770::posit_event(int new_event_type) {
 		});
 		WAIT_FOR_EVENT(Event::DataWritten);
 		if(status_.data_request) {
-			get_drive().end_writing();
+			end_writing();
 			update_status([] (Status &status) {
 				status.lost_data = true;
 			});
@@ -554,7 +554,7 @@ void WD1770::posit_event(int new_event_type) {
 		write_crc();
 		write_byte(0xff);
 		WAIT_FOR_EVENT(Event::DataWritten);
-		get_drive().end_writing();
+		end_writing();
 
 		if(command_ & 0x10) {
 			sector_++;
@@ -755,11 +755,11 @@ void WD1770::posit_event(int new_event_type) {
 			update_status([] (Status &status) {
 				status.lost_data = true;
 			});
-			get_drive().end_writing();
+			end_writing();
 			goto wait_for_command;
 		}
 		if(index_hole_count_) {
-			get_drive().end_writing();
+			end_writing();
 			goto wait_for_command;
 		}
 

Components/8272/i8272.cpp

@@ -525,7 +525,7 @@ void i8272::posit_event(int event_type) {
 			WAIT_FOR_EVENT(Event::DataWritten);
 			if(!has_input_) {
 				SetOverrun();
-				get_drive().end_writing();
+				end_writing();
 				goto abort;
 			}
 			write_byte(input_);
@@ -540,7 +540,7 @@ void i8272::posit_event(int event_type) {
 			write_crc();
 			expects_input_ = false;
 			WAIT_FOR_EVENT(Event::DataWritten);
-			get_drive().end_writing();
+			end_writing();
 
 			if(sector_ != command_[6]) {
 				sector_++;
@@ -646,7 +646,7 @@ void i8272::posit_event(int event_type) {
 			switch(event_type) {
 				case (int)Event::IndexHole:
 					SetOverrun();
-					get_drive().end_writing();
+					end_writing();
 					goto abort;
 				break;
 				case (int)Event::DataWritten:
@@ -683,7 +683,7 @@ void i8272::posit_event(int event_type) {
 			WAIT_FOR_EVENT((int)Event::DataWritten | (int)Event::IndexHole);
 			if(event_type != (int)Event::IndexHole) goto format_track_pad;
 
-			get_drive().end_writing();
+			end_writing();
 
 			cylinder_ = header_[0];
 			head_ = header_[1];

Storage/Disk/DiskController.cpp

@@ -48,7 +48,7 @@ void Controller::process_event(const Track::Event &event) {
 }
 
 void Controller::advance(const Cycles cycles) {
-	pll_->run_for(Cycles(cycles.as_int() * clock_rate_multiplier_));
+	if(is_reading_) pll_->run_for(Cycles(cycles.as_int() * clock_rate_multiplier_));
 }
 
 void Controller::process_write_completed() {
@@ -72,7 +72,7 @@ void Controller::set_expected_bit_length(Time bit_length) {
 }
 
 void Controller::digital_phase_locked_loop_output_bit(int value) {
-	process_input_bit(value);
+	if(is_reading_) process_input_bit(value);
 }
 
 void Controller::set_drive(std::shared_ptr<Drive> drive) {
@@ -99,5 +99,15 @@ void Controller::set_drive(std::shared_ptr<Drive> drive) {
 }
 
 void Controller::begin_writing(bool clamp_to_index_hole) {
+	is_reading_ = false;
 	get_drive().begin_writing(bit_length_, clamp_to_index_hole);
 }
+
+void Controller::end_writing() {
+	is_reading_ = true;
+	get_drive().end_writing();
+}
+
+bool Controller::is_reading() {
+	return is_reading_;
+}

Storage/Disk/DiskController.hpp

@@ -68,13 +68,25 @@ class Controller: public DigitalPhaseLockedLoop::Delegate, public Drive::EventDe
 		virtual void process_write_completed();
 
 		/*!
-			Puts the drive returned by get_drive() into write mode, supplying the current bit length.
+			Puts the drive returned by get_drive() into write mode, supplying the current bit length
+			and marks the controller as being in write mode.
 
 			@param clamp_to_index_hole If @c true then writing will automatically be truncated by
 			the index hole. Writing will continue over the index hole otherwise.
 		*/
 		void begin_writing(bool clamp_to_index_hole);
 
+		/*!
+			Puts the drive returned by get_drive() out of write mode, and marks the controller
+			as no longer being in write mode.
+		*/
+		void end_writing();
+
+		/*!
+			@returns @c true if the controller is in reading mode; @c false otherwise.
+		*/
+		bool is_reading();
+
 		/*!
 			Returns the connected drive or, if none is connected, an invented one. No guarantees are
 			made about the lifetime or the exclusivity of the invented drive.
@@ -85,8 +97,10 @@ class Controller: public DigitalPhaseLockedLoop::Delegate, public Drive::EventDe
 
 	private:
 		Time bit_length_;
-		int clock_rate_multiplier_;
+		int clock_rate_multiplier_ = 1;
-		int clock_rate_;
+		int clock_rate_ = 1;
+
+		bool is_reading_ = true;
 
 		std::shared_ptr<DigitalPhaseLockedLoop> pll_;
 		std::shared_ptr<Drive> drive_;