diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj
index 06204d82f..ba1162644 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
@@ -7,6 +7,7 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		4B0BE4281D3481E700D5256B /* DigitalPhaseLockedLoop.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B0BE4261D3481E700D5256B /* DigitalPhaseLockedLoop.cpp */; };
 		4B0CCC451C62D0B3001CAC5F /* CRT.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4B0CCC421C62D0B3001CAC5F /* CRT.cpp */; };
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@@ -354,6 +355,8 @@
 /* Begin PBXFileReference section */
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 		4B0B6E121C9DBD5D00FFB60D /* CRTConstants.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = CRTConstants.hpp; sourceTree = "<group>"; };
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@@ -989,6 +992,8 @@
 				4BAB62AC1D3272D200DF5BA0 /* Disk.hpp */,
 				4BAB62B61D3302CA00DF5BA0 /* PCMTrack.cpp */,
 				4BAB62B71D3302CA00DF5BA0 /* PCMTrack.hpp */,
+				4B0BE4261D3481E700D5256B /* DigitalPhaseLockedLoop.cpp */,
+				4B0BE4271D3481E700D5256B /* DigitalPhaseLockedLoop.hpp */,
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 				4BBB14311CD2CECE00BDB55C /* IntermediateShader.cpp in Sources */,
 				4BD5F1951D13528900631CD1 /* CSBestEffortUpdater.m in Sources */,
+				4B0BE4281D3481E700D5256B /* DigitalPhaseLockedLoop.cpp in Sources */,
 				4B73C71A1D036BD90074D992 /* Vic20Document.swift in Sources */,
 				4BBF99181C8FBA6F0075DAFB /* TextureTarget.cpp in Sources */,
 				4BC76E691C98E31700E6EF73 /* FIRFilter.cpp in Sources */,
diff --git a/Storage/Disk/DigitalPhaseLockedLoop.cpp b/Storage/Disk/DigitalPhaseLockedLoop.cpp
new file mode 100644
index 000000000..5d1319fc3
--- /dev/null
+++ b/Storage/Disk/DigitalPhaseLockedLoop.cpp
@@ -0,0 +1,9 @@
+//
+//  DigitalPhaseLockedLoop.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 11/07/2016.
+//  Copyright © 2016 Thomas Harte. All rights reserved.
+//
+
+#include "DigitalPhaseLockedLoop.hpp"
diff --git a/Storage/Disk/DigitalPhaseLockedLoop.hpp b/Storage/Disk/DigitalPhaseLockedLoop.hpp
new file mode 100644
index 000000000..f8b3910c1
--- /dev/null
+++ b/Storage/Disk/DigitalPhaseLockedLoop.hpp
@@ -0,0 +1,54 @@
+//
+//  DigitalPhaseLockedLoop.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 11/07/2016.
+//  Copyright © 2016 Thomas Harte. All rights reserved.
+//
+
+#ifndef DigitalPhaseLockedLoop_hpp
+#define DigitalPhaseLockedLoop_hpp
+
+namespace Storage {
+
+class DigitalPhaseLockedLoop {
+	public:
+		/*!
+			Instantiates a @c DigitalPhaseLockedLoop.
+
+			@param clocks_per_bit The expected number of cycles between each bit of input.
+			@param tolerance The maximum tolerance for bit windows — extremes will be clocks_per_bit ± tolerance.
+		*/
+		DigitalPhaseLockedLoop(unsigned int clocks_per_bit, unsigned int tolerance);
+
+		/*!
+			Runs the loop, impliedly posting no pulses during that period.
+
+			@c number_of_cycles The time to run the loop for.
+		*/
+		void run_for_cycles(unsigned int number_of_cycles);
+
+		/*!
+			Announces a pulse at the current time.
+		*/
+		void add_pulse();
+
+		/*!
+			A receiver for PCM output data; called upon every recognised bit.
+		*/
+		class Delegate {
+			public:
+				virtual void digital_phase_locked_loop_output_bit(bool value) = 0;
+		};
+		void set_delegate(Delegate *delegate)
+		{
+			_delegate = delegate;
+		}
+
+	private:
+		Delegate *_delegate;
+};
+
+}
+
+#endif /* DigitalPhaseLockedLoop_hpp */