diff --git a/ClockReceiver/ClockReceiver.hpp b/ClockReceiver/ClockReceiver.hpp
index 482025d52..ba4a67629 100644
--- a/ClockReceiver/ClockReceiver.hpp
+++ b/ClockReceiver/ClockReceiver.hpp
@@ -149,8 +149,8 @@ template <class T> class WrappedInt {
 			Flushes the value in @c this. The current value is returned, and the internal value
 			is reset to zero.
 		*/
-		forceinline T flush() {
-			T result(length_);
+		template <typename Target> forceinline Target flush() {
+			const Target result(length_);
 			length_ = 0;
 			return result;
 		}
@@ -185,8 +185,8 @@ class HalfCycles: public WrappedInt<HalfCycles> {
 		}
 
 		/// Flushes the whole cycles in @c this, subtracting that many from the total stored here.
-		forceinline Cycles flush_cycles() {
-			Cycles result(length_ >> 1);
+		template <typename Cycles> forceinline Cycles flush() {
+			const Cycles result(length_ >> 1);
 			length_ &= 1;
 			return result;
 		}
@@ -220,7 +220,7 @@ template <class T> class HalfClockReceiver: public T {
 
 		forceinline void run_for(const HalfCycles half_cycles) {
 			half_cycles_ += half_cycles;
-			T::run_for(half_cycles_.flush_cycles());
+			T::run_for(half_cycles_.flush<Cycles>());
 		}
 
 	private:
diff --git a/ClockReceiver/ClockDeferrer.hpp b/ClockReceiver/DeferredQueue.hpp
similarity index 85%
rename from ClockReceiver/ClockDeferrer.hpp
rename to ClockReceiver/DeferredQueue.hpp
index cc41cbdd0..d2680f322 100644
--- a/ClockReceiver/ClockDeferrer.hpp
+++ b/ClockReceiver/DeferredQueue.hpp
@@ -1,26 +1,26 @@
 //
-//  ClockDeferrer.hpp
+//  DeferredQueue.hpp
 //  Clock Signal
 //
 //  Created by Thomas Harte on 23/08/2018.
 //  Copyright © 2018 Thomas Harte. All rights reserved.
 //
 
-#ifndef ClockDeferrer_h
-#define ClockDeferrer_h
+#ifndef DeferredQueue_h
+#define DeferredQueue_h
 
 #include <functional>
 #include <vector>
 
 /*!
-	A ClockDeferrer maintains a list of ordered actions and the times at which
+	A DeferredQueue maintains a list of ordered actions and the times at which
 	they should happen, and divides a total execution period up into the portions
 	that occur between those actions, triggering each action when it is reached.
 */
-template <typename TimeUnit> class ClockDeferrer {
+template <typename TimeUnit> class DeferredQueue {
 	public:
-		/// Constructs a ClockDeferrer that will call target(period) in between deferred actions.
-		ClockDeferrer(std::function<void(TimeUnit)> &&target) : target_(std::move(target)) {}
+		/// Constructs a DeferredQueue that will call target(period) in between deferred actions.
+		DeferredQueue(std::function<void(TimeUnit)> &&target) : target_(std::move(target)) {}
 
 		/*!
 			Schedules @c action to occur in @c delay units of time.
@@ -79,4 +79,4 @@ template <typename TimeUnit> class ClockDeferrer {
 		std::vector<DeferredAction> pending_actions_;
 };
 
-#endif /* ClockDeferrer_h */
+#endif /* DeferredQueue_h */
diff --git a/ClockReceiver/JustInTime.hpp b/ClockReceiver/JustInTime.hpp
new file mode 100644
index 000000000..e9a3dd72b
--- /dev/null
+++ b/ClockReceiver/JustInTime.hpp
@@ -0,0 +1,55 @@
+//
+//  JustInTime.hpp
+//  Clock Signal
+//
+//  Created by Thomas Harte on 28/07/2019.
+//  Copyright © 2019 Thomas Harte. All rights reserved.
+//
+
+#ifndef JustInTime_h
+#define JustInTime_h
+
+//#include "../Concurrency/AsyncTaskQueue.hpp"
+
+/*!
+	A JustInTimeActor holds (i) an embedded object with a run_for method; and (ii) an amount
+	of time since run_for was last called.
+
+	Time can be added using the += operator. The -> operator can be used to access the
+	embedded object. All time accumulated will be pushed to object before the pointer is returned.
+
+	Machines that accumulate HalfCycle time but supply to a Cycle-counted device may supply a
+	separate @c TargetTimeScale at template declaration.
+*/
+template <class T, class LocalTimeScale, class TargetTimeScale = LocalTimeScale> class JustInTimeActor {
+	public:
+		/// Constructs a new JustInTimeActor using the same construction arguments as the included object.
+		template<typename... Args> JustInTimeActor(Args&&... args) : object_(std::forward<Args>(args)...) {}
+
+		/// Adds time to the actor.
+		inline void operator += (const TimeScale &rhs) {
+			time_since_update_ += rhs;
+		}
+
+		/// Flushes all accumulated time and returns a pointer to the included object.
+		inline T *operator->() {
+			object_.run_for(time_since_update_.template flush<TargetTimeScale>());
+			return &object_;
+		}
+
+	private:
+		T object_;
+		LocalTimeScale time_since_update_;
+
+};
+
+/*!
+	A JustInTimeAsyncActor acts like a JustInTimeActor but additionally contains an AsyncTaskQueue.
+	Any time the amount of accumulated time crosses a threshold provided at construction time,
+	the object will be updated on the AsyncTaskQueue.
+*/
+template <class T, class TimeScale> class JustInTimeAsyncActor {
+
+};
+
+#endif /* JustInTime_h */
diff --git a/Machines/Apple/AppleII/AppleII.cpp b/Machines/Apple/AppleII/AppleII.cpp
index 8a857c6ef..e39dec9da 100644
--- a/Machines/Apple/AppleII/AppleII.cpp
+++ b/Machines/Apple/AppleII/AppleII.cpp
@@ -77,7 +77,7 @@ template <Analyser::Static::AppleII::Target::Model model> class ConcreteMachine:
 		Cycles cycles_since_video_update_;
 
 		void update_video() {
-			video_.run_for(cycles_since_video_update_.flush());
+			video_.run_for(cycles_since_video_update_.flush<Cycles>());
 		}
 		static const int audio_divider = 8;
 		void update_audio() {
diff --git a/Machines/Apple/AppleII/Video.hpp b/Machines/Apple/AppleII/Video.hpp
index 7ae6b179b..e74b06c25 100644
--- a/Machines/Apple/AppleII/Video.hpp
+++ b/Machines/Apple/AppleII/Video.hpp
@@ -11,7 +11,7 @@
 
 #include "../../../Outputs/CRT/CRT.hpp"
 #include "../../../ClockReceiver/ClockReceiver.hpp"
-#include "../../../ClockReceiver/ClockDeferrer.hpp"
+#include "../../../ClockReceiver/DeferredQueue.hpp"
 
 #include <array>
 #include <vector>
@@ -251,8 +251,8 @@ class VideoBase {
 		*/
 		void output_fat_low_resolution(uint8_t *target, const uint8_t *source, size_t length, int column, int row) const;
 
-		// Maintain a ClockDeferrer for delayed mode switches.
-		ClockDeferrer<Cycles> deferrer_;
+		// Maintain a DeferredQueue for delayed mode switches.
+		DeferredQueue<Cycles> deferrer_;
 };
 
 template <class BusHandler, bool is_iie> class Video: public VideoBase {
diff --git a/Machines/Apple/Macintosh/DeferredAudio.hpp b/Machines/Apple/Macintosh/DeferredAudio.hpp
index 72ebc6b10..6fda448fa 100644
--- a/Machines/Apple/Macintosh/DeferredAudio.hpp
+++ b/Machines/Apple/Macintosh/DeferredAudio.hpp
@@ -24,7 +24,7 @@ struct DeferredAudio {
 	DeferredAudio() : audio(queue), speaker(audio) {}
 
 	void flush() {
-		speaker.run_for(queue, time_since_update.flush_cycles());
+		speaker.run_for(queue, time_since_update.flush<Cycles>());
 	}
 };
 
diff --git a/Machines/Apple/Macintosh/Macintosh.cpp b/Machines/Apple/Macintosh/Macintosh.cpp
index 802288ad9..44c84a3e9 100644
--- a/Machines/Apple/Macintosh/Macintosh.cpp
+++ b/Machines/Apple/Macintosh/Macintosh.cpp
@@ -24,6 +24,8 @@
 #include "../../../Inputs/QuadratureMouse/QuadratureMouse.hpp"
 #include "../../../Outputs/Log.hpp"
 
+#include "../../../ClockReceiver/JustInTime.hpp"
+
 //#define LOG_TRACE
 
 #include "../../../Components/6522/6522.hpp"
@@ -471,7 +473,7 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
 			Apple::IWM iwm;
 
 			void flush() {
-				iwm.run_for(time_since_update.flush_cycles());
+				iwm.run_for(time_since_update.flush<Cycles>());
 			}
 		};
 
@@ -610,7 +612,6 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
  		HalfCycles keyboard_clock_;
  		HalfCycles time_since_video_update_;
  		HalfCycles time_until_video_event_;
- 		HalfCycles time_since_iwm_update_;
  		HalfCycles time_since_mouse_update_;
 
 		bool ROM_is_overlay_ = true;
diff --git a/Machines/Atari2600/Bus.hpp b/Machines/Atari2600/Bus.hpp
index ba58c81c5..efcb05091 100644
--- a/Machines/Atari2600/Bus.hpp
+++ b/Machines/Atari2600/Bus.hpp
@@ -55,13 +55,13 @@ class Bus {
 		// video backlog accumulation counter
 		Cycles cycles_since_video_update_;
 		inline void update_video() {
-			tia_.run_for(cycles_since_video_update_.flush());
+			tia_.run_for(cycles_since_video_update_.flush<Cycles>());
 		}
 
 		// RIOT backlog accumulation counter
 		Cycles cycles_since_6532_update_;
 		inline void update_6532() {
-			mos6532_.run_for(cycles_since_6532_update_.flush());
+			mos6532_.run_for(cycles_since_6532_update_.flush<Cycles>());
 		}
 };
 
diff --git a/Machines/Commodore/Vic-20/Vic20.cpp b/Machines/Commodore/Vic-20/Vic20.cpp
index 2ac58a2e5..4c65dc304 100644
--- a/Machines/Commodore/Vic-20/Vic20.cpp
+++ b/Machines/Commodore/Vic-20/Vic20.cpp
@@ -702,7 +702,7 @@ class ConcreteMachine:
 
 	private:
 		void update_video() {
-			mos6560_.run_for(cycles_since_mos6560_update_.flush());
+			mos6560_.run_for(cycles_since_mos6560_update_.flush<Cycles>());
 		}
 		CPU::MOS6502::Processor<CPU::MOS6502::Personality::P6502, ConcreteMachine, false> m6502_;
 
diff --git a/Machines/Electron/Electron.cpp b/Machines/Electron/Electron.cpp
index f0a31815e..e87f2641f 100644
--- a/Machines/Electron/Electron.cpp
+++ b/Machines/Electron/Electron.cpp
@@ -510,7 +510,7 @@ class ConcreteMachine:
 		// MARK: - Work deferral updates.
 		inline void update_display() {
 			if(cycles_since_display_update_ > 0) {
-				video_output_.run_for(cycles_since_display_update_.flush());
+				video_output_.run_for(cycles_since_display_update_.flush<Cycles>());
 			}
 		}
 
diff --git a/Machines/Oric/Oric.cpp b/Machines/Oric/Oric.cpp
index b90ce9fd8..158acc11e 100644
--- a/Machines/Oric/Oric.cpp
+++ b/Machines/Oric/Oric.cpp
@@ -182,7 +182,7 @@ class VIAPortHandler: public MOS::MOS6522::IRQDelegatePortHandler {
 
 	private:
 		void update_ay() {
-			speaker_.run_for(audio_queue_, cycles_since_ay_update_.flush_cycles());
+			speaker_.run_for(audio_queue_, cycles_since_ay_update_.flush<Cycles>());
 		}
 		bool ay_bdir_ = false;
 		bool ay_bc1_ = false;
@@ -585,7 +585,7 @@ template <Analyser::Static::Oric::Target::DiskInterface disk_interface> class Co
 		uint8_t ram_[65536];
 		Cycles cycles_since_video_update_;
 		inline void update_video() {
-			video_output_.run_for(cycles_since_video_update_.flush());
+			video_output_.run_for(cycles_since_video_update_.flush<Cycles>());
 		}
 
 		// ROM bookkeeping
@@ -617,7 +617,7 @@ template <Analyser::Static::Oric::Target::DiskInterface disk_interface> class Co
 		Apple::DiskII diskii_;
 		Cycles cycles_since_diskii_update_;
 		void flush_diskii() {
-			diskii_.run_for(cycles_since_diskii_update_.flush());
+			diskii_.run_for(cycles_since_diskii_update_.flush<Cycles>());
 		}
 		std::vector<uint8_t> pravetz_rom_;
 		std::size_t pravetz_rom_base_pointer_ = 0;
diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj
index d43ce8c20..c5ea334a6 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj	
@@ -983,6 +983,7 @@
 		4B7F188D2154825D00388727 /* MasterSystem.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = MasterSystem.hpp; sourceTree = "<group>"; };
 		4B7F1895215486A100388727 /* StaticAnalyser.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = StaticAnalyser.hpp; sourceTree = "<group>"; };
 		4B7F1896215486A100388727 /* StaticAnalyser.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = StaticAnalyser.cpp; sourceTree = "<group>"; };
+		4B80214322EE7C3E00068002 /* JustInTime.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = JustInTime.hpp; sourceTree = "<group>"; };
 		4B80ACFE1F85CAC900176895 /* BestEffortUpdater.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = BestEffortUpdater.cpp; path = ../../Concurrency/BestEffortUpdater.cpp; sourceTree = "<group>"; };
 		4B80ACFF1F85CACA00176895 /* BestEffortUpdater.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; name = BestEffortUpdater.hpp; path = ../../Concurrency/BestEffortUpdater.hpp; sourceTree = "<group>"; };
 		4B8334811F5D9FF70097E338 /* PartialMachineCycle.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = PartialMachineCycle.cpp; sourceTree = "<group>"; };
@@ -1051,7 +1052,7 @@
 		4B894516201967B4007DE474 /* StaticAnalyser.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = StaticAnalyser.cpp; sourceTree = "<group>"; };
 		4B894517201967B4007DE474 /* StaticAnalyser.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = StaticAnalyser.cpp; sourceTree = "<group>"; };
 		4B894540201967D6007DE474 /* Machines.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = Machines.hpp; sourceTree = "<group>"; };
-		4B8A7E85212F988200F2BBC6 /* ClockDeferrer.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = ClockDeferrer.hpp; sourceTree = "<group>"; };
+		4B8A7E85212F988200F2BBC6 /* DeferredQueue.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = DeferredQueue.hpp; sourceTree = "<group>"; };
 		4B8D287E1F77207100645199 /* TrackSerialiser.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = TrackSerialiser.hpp; sourceTree = "<group>"; };
 		4B8E4ECD1DCE483D003716C3 /* KeyboardMachine.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = KeyboardMachine.hpp; sourceTree = "<group>"; };
 		4B8EF6071FE5AF830076CCDD /* LowpassSpeaker.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = LowpassSpeaker.hpp; sourceTree = "<group>"; };
@@ -3383,10 +3384,11 @@
 		4BF660691F281573002CB053 /* ClockReceiver */ = {
 			isa = PBXGroup;
 			children = (
-				4B8A7E85212F988200F2BBC6 /* ClockDeferrer.hpp */,
 				4BB146C61F49D7D700253439 /* ClockingHintSource.hpp */,
 				4BF6606A1F281573002CB053 /* ClockReceiver.hpp */,
+				4B8A7E85212F988200F2BBC6 /* DeferredQueue.hpp */,
 				4BB06B211F316A3F00600C7A /* ForceInline.hpp */,
+				4B80214322EE7C3E00068002 /* JustInTime.hpp */,
 				4B449C942063389900A095C8 /* TimeTypes.hpp */,
 			);
 			name = ClockReceiver;