diff --git a/Components/1770/1770.hpp b/Components/1770/1770.hpp
index 3d36b6d5e..32941fc1d 100644
--- a/Components/1770/1770.hpp
+++ b/Components/1770/1770.hpp
@@ -9,6 +9,19 @@
 #ifndef _770_hpp
 #define _770_hpp
 
-#include <stdio.h>
+#include "../../Storage/Disk/DiskDrive.hpp"
+
+namespace WD {
+
+class WD1770 {
+	public:
+
+		void set_drive(std::shared_ptr<Storage::Disk::Drive> drive);
+		void set_is_double_density(bool is_double_density);
+		void set_register(int address, uint8_t value);
+		void get_register(int address);
+};
+
+}
 
 #endif /* _770_hpp */
diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj
index ef1d6073c..f0b7f1e0a 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
@@ -355,6 +355,7 @@
 		4BEF6AAA1D35CE9E00E73575 /* DigitalPhaseLockedLoopBridge.mm in Sources */ = {isa = PBXBuildFile; fileRef = 4BEF6AA91D35CE9E00E73575 /* DigitalPhaseLockedLoopBridge.mm */; };
 		4BEF6AAC1D35D1C400E73575 /* DPLLTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4BEF6AAB1D35D1C400E73575 /* DPLLTests.swift */; };
 		4BF1354C1D6D2C300054B2EA /* StaticAnalyser.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BF1354A1D6D2C300054B2EA /* StaticAnalyser.cpp */; };
+		4BF8295D1D8F048B001BAE39 /* MFM.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BF8295B1D8F048B001BAE39 /* MFM.cpp */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -805,6 +806,8 @@
 		4BEF6AAB1D35D1C400E73575 /* DPLLTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = DPLLTests.swift; sourceTree = "<group>"; };
 		4BF1354A1D6D2C300054B2EA /* StaticAnalyser.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = StaticAnalyser.cpp; path = ../../StaticAnalyser/StaticAnalyser.cpp; sourceTree = "<group>"; };
 		4BF1354B1D6D2C300054B2EA /* StaticAnalyser.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; name = StaticAnalyser.hpp; path = ../../StaticAnalyser/StaticAnalyser.hpp; sourceTree = "<group>"; };
+		4BF8295B1D8F048B001BAE39 /* MFM.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = MFM.cpp; path = Encodings/MFM.cpp; sourceTree = "<group>"; };
+		4BF8295C1D8F048B001BAE39 /* MFM.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; name = MFM.hpp; path = Encodings/MFM.hpp; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -1400,6 +1403,8 @@
 			children = (
 				4BB697CC1D4BA44400248BDF /* CommodoreGCR.cpp */,
 				4BB697CD1D4BA44400248BDF /* CommodoreGCR.hpp */,
+				4BF8295B1D8F048B001BAE39 /* MFM.cpp */,
+				4BF8295C1D8F048B001BAE39 /* MFM.hpp */,
 			);
 			name = Encodings;
 			sourceTree = "<group>";
@@ -2091,6 +2096,7 @@
 				4BC830D11D6E7C690000A26F /* Tape.cpp in Sources */,
 				4B69FB441C4D941400B5F0AA /* TapeUEF.cpp in Sources */,
 				4B4DC8211D2C2425003C5BF8 /* Vic20.cpp in Sources */,
+				4BF8295D1D8F048B001BAE39 /* MFM.cpp in Sources */,
 				4BE77A2E1D84ADFB00BC3827 /* File.cpp in Sources */,
 				4BAB62B51D327F7E00DF5BA0 /* G64.cpp in Sources */,
 				4BD468F71D8DF41D0084958B /* 1770.cpp in Sources */,
diff --git a/OSBindings/Mac/Clock Signal/Info.plist b/OSBindings/Mac/Clock Signal/Info.plist
index cd2e9b763..412ff4196 100644
--- a/OSBindings/Mac/Clock Signal/Info.plist	
+++ b/OSBindings/Mac/Clock Signal/Info.plist	
@@ -130,6 +130,20 @@
 			<key>NSDocumentClass</key>
 			<string>$(PRODUCT_MODULE_NAME).Vic20Document</string>
 		</dict>
+		<dict>
+			<key>CFBundleTypeExtensions</key>
+			<array>
+				<string>ssd</string>
+				<string>dsd</string>
+				<string>adf</string>
+				<string>adl</string>
+				<string>adm</string>
+			</array>
+			<key>CFBundleTypeName</key>
+			<string>Electron/BBC Disk Image</string>
+			<key>CFBundleTypeRole</key>
+			<string>Viewer</string>
+		</dict>
 	</array>
 	<key>CFBundleExecutable</key>
 	<string>$(EXECUTABLE_NAME)</string>
diff --git a/Storage/Disk/Encodings/CommodoreGCR.hpp b/Storage/Disk/Encodings/CommodoreGCR.hpp
index 34346e253..9b8a0c055 100644
--- a/Storage/Disk/Encodings/CommodoreGCR.hpp
+++ b/Storage/Disk/Encodings/CommodoreGCR.hpp
@@ -6,8 +6,8 @@
 //  Copyright © 2016 Thomas Harte. All rights reserved.
 //
 
-#ifndef CommodoreGCR_hpp
-#define CommodoreGCR_hpp
+#ifndef Storage_Disk_Encodings_CommodoreGCR_hpp
+#define Storage_Disk_Encodings_CommodoreGCR_hpp
 
 #include "../../Storage.hpp"
 #include <cstdint>
diff --git a/Storage/Disk/Encodings/MFM.cpp b/Storage/Disk/Encodings/MFM.cpp
new file mode 100644
index 000000000..efb0797b2
--- /dev/null
+++ b/Storage/Disk/Encodings/MFM.cpp
@@ -0,0 +1,50 @@
+//
+//  MFM.cpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 18/09/2016.
+//  Copyright © 2016 Thomas Harte. All rights reserved.
+//
+
+#include "MFM.hpp"
+
+using namespace Storage::Encodings;
+
+void Shifter::add_sync()
+{
+	// i.e. 0100 0100 1000 1001
+	output = (uint16_t)((output << 15) | 0x4489);
+}
+
+void MFMShifter::shift(uint8_t input)
+{
+	uint16_t spread_value =
+		(uint16_t)(
+			((input & 0x01) << 0) |
+			((input & 0x02) << 1) |
+			((input & 0x04) << 2) |
+			((input & 0x08) << 3) |
+			((input & 0x10) << 4) |
+			((input & 0x20) << 5) |
+			((input & 0x40) << 6) |
+			((input & 0x80) << 7)
+		);
+	uint16_t or_bits = (uint16_t)((spread_value << 1) | (spread_value >> 1) | (output << 15));
+	output = spread_value | ((~or_bits) & 0xaaaa);
+}
+
+void FMShifter::shift(uint8_t input)
+{
+	output =
+		(uint16_t)(
+			((input & 0x01) << 0) |
+			((input & 0x02) << 1) |
+			((input & 0x04) << 2) |
+			((input & 0x08) << 3) |
+			((input & 0x10) << 4) |
+			((input & 0x20) << 5) |
+			((input & 0x40) << 6) |
+			((input & 0x80) << 7) |
+			0xaaaa
+		);
+}
diff --git a/Storage/Disk/Encodings/MFM.hpp b/Storage/Disk/Encodings/MFM.hpp
new file mode 100644
index 000000000..2e3c8f2c4
--- /dev/null
+++ b/Storage/Disk/Encodings/MFM.hpp
@@ -0,0 +1,37 @@
+//
+//  MFM.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 18/09/2016.
+//  Copyright © 2016 Thomas Harte. All rights reserved.
+//
+
+#ifndef Storage_Disk_Encodings_MFM_hpp
+#define Storage_Disk_Encodings_MFM_hpp
+
+#include <cstdint>
+
+namespace Storage {
+namespace Encodings {
+
+class Shifter {
+	public:
+		virtual void shift(uint8_t input) = 0;
+		void add_sync();
+		uint16_t output;
+};
+
+class MFMShifter: public Shifter {
+	public:
+		void shift(uint8_t input);
+};
+
+class FMShifter: public Shifter {
+	public:
+		void shift(uint8_t input);
+};
+
+}
+}
+
+#endif /* MFM_hpp */