diff --git a/Analyser/Dynamic/MultiMachine/Implementation/MultiKeyboardMachine.cpp b/Analyser/Dynamic/MultiMachine/Implementation/MultiKeyboardMachine.cpp
index d7ec688c6..5c12ff92f 100644
--- a/Analyser/Dynamic/MultiMachine/Implementation/MultiKeyboardMachine.cpp
+++ b/Analyser/Dynamic/MultiMachine/Implementation/MultiKeyboardMachine.cpp
@@ -36,7 +36,7 @@ void MultiKeyboardMachine::type_string(const std::string &string) {
 	}
 }
 
-bool MultiKeyboardMachine::can_type(char c) {
+bool MultiKeyboardMachine::can_type(char c) const {
 	bool can_type = true;
 	for(const auto &machine: machines_) {
 		can_type &= machine->can_type(c);
@@ -70,10 +70,10 @@ void MultiKeyboardMachine::MultiKeyboard::reset_all_keys() {
 	}
 }
 
-const std::set<Inputs::Keyboard::Key> &MultiKeyboardMachine::MultiKeyboard::observed_keys() {
+const std::set<Inputs::Keyboard::Key> &MultiKeyboardMachine::MultiKeyboard::observed_keys() const {
 	return observed_keys_;
 }
 
-bool MultiKeyboardMachine::MultiKeyboard::is_exclusive() {
+bool MultiKeyboardMachine::MultiKeyboard::is_exclusive() const {
 	return is_exclusive_;
 }
diff --git a/Analyser/Dynamic/MultiMachine/Implementation/MultiKeyboardMachine.hpp b/Analyser/Dynamic/MultiMachine/Implementation/MultiKeyboardMachine.hpp
index 723cb05a7..aa5433563 100644
--- a/Analyser/Dynamic/MultiMachine/Implementation/MultiKeyboardMachine.hpp
+++ b/Analyser/Dynamic/MultiMachine/Implementation/MultiKeyboardMachine.hpp
@@ -34,8 +34,8 @@ class MultiKeyboardMachine: public MachineTypes::KeyboardMachine {
 
 				bool set_key_pressed(Key key, char value, bool is_pressed) final;
 				void reset_all_keys() final;
-				const std::set<Key> &observed_keys() final;
-				bool is_exclusive() final;
+				const std::set<Key> &observed_keys() const final;
+				bool is_exclusive() const final;
 
 			private:
 				const std::vector<MachineTypes::KeyboardMachine *> &machines_;
@@ -51,7 +51,7 @@ class MultiKeyboardMachine: public MachineTypes::KeyboardMachine {
 		void clear_all_keys() final;
 		void set_key_state(uint16_t key, bool is_pressed) final;
 		void type_string(const std::string &) final;
-		bool can_type(char c) final;
+		bool can_type(char c) const final;
 		Inputs::Keyboard &get_keyboard() final;
 };
 
diff --git a/ClockReceiver/DeferredQueue.hpp b/ClockReceiver/DeferredQueue.hpp
index be1c7b01e..a2015aea3 100644
--- a/ClockReceiver/DeferredQueue.hpp
+++ b/ClockReceiver/DeferredQueue.hpp
@@ -49,7 +49,7 @@ template <typename TimeUnit> class DeferredQueue {
 			@returns The amount of time until the next enqueued action will occur,
 				or TimeUnit(-1) if the queue is empty.
 		*/
-		TimeUnit time_until_next_action() {
+		TimeUnit time_until_next_action() const {
 			if(pending_actions_.empty()) return TimeUnit(-1);
 			return pending_actions_.front().delay;
 		}
@@ -95,7 +95,7 @@ template <typename TimeUnit> class DeferredQueue {
 template <typename TimeUnit> class DeferredQueuePerformer: public DeferredQueue<TimeUnit> {
 	public:
 		/// Constructs a DeferredQueue that will call target(period) in between deferred actions.
-		DeferredQueuePerformer(std::function<void(TimeUnit)> &&target) : target_(std::move(target)) {}
+		constexpr DeferredQueuePerformer(std::function<void(TimeUnit)> &&target) : target_(std::move(target)) {}
 
 		/*!
 			Runs for @c length units of time.
diff --git a/Components/9918/9918.cpp b/Components/9918/9918.cpp
index 42b4e8a44..11512c7ae 100644
--- a/Components/9918/9918.cpp
+++ b/Components/9918/9918.cpp
@@ -129,7 +129,7 @@ void TMS9918::set_display_type(Outputs::Display::DisplayType display_type) {
 	crt_.set_display_type(display_type);
 }
 
-Outputs::Display::DisplayType TMS9918::get_display_type() {
+Outputs::Display::DisplayType TMS9918::get_display_type() const {
 	return crt_.get_display_type();
 }
 
diff --git a/Components/9918/9918.hpp b/Components/9918/9918.hpp
index 4f2530bf3..70f9d55c1 100644
--- a/Components/9918/9918.hpp
+++ b/Components/9918/9918.hpp
@@ -51,7 +51,7 @@ class TMS9918: public Base {
 		void set_display_type(Outputs::Display::DisplayType);
 
 		/*! Gets the type of display the CRT will request. */
-		Outputs::Display::DisplayType get_display_type();
+		Outputs::Display::DisplayType get_display_type() const;
 
 		/*!
 			Runs the VCP for the number of cycles indicate; it is an implicit assumption of the code
diff --git a/Inputs/Keyboard.cpp b/Inputs/Keyboard.cpp
index 16c342f71..6491744e5 100644
--- a/Inputs/Keyboard.cpp
+++ b/Inputs/Keyboard.cpp
@@ -30,7 +30,7 @@ bool Keyboard::set_key_pressed(Key key, char value, bool is_pressed) {
 	return false;
 }
 
-const std::set<Inputs::Keyboard::Key> &Keyboard::get_essential_modifiers() {
+const std::set<Inputs::Keyboard::Key> &Keyboard::get_essential_modifiers() const {
 	return essential_modifiers_;
 }
 
@@ -43,16 +43,16 @@ void Keyboard::set_delegate(Delegate *delegate) {
 	delegate_ = delegate;
 }
 
-bool Keyboard::get_key_state(Key key) {
+bool Keyboard::get_key_state(Key key) const {
 	const size_t key_offset = size_t(key);
 	if(key_offset >= key_states_.size()) return false;
 	return key_states_[key_offset];
 }
 
-const std::set<Keyboard::Key> &Keyboard::observed_keys() {
+const std::set<Keyboard::Key> &Keyboard::observed_keys() const {
 	return observed_keys_;
 }
 
-bool Keyboard::is_exclusive() {
+bool Keyboard::is_exclusive() const {
 	return is_exclusive_;
 }
diff --git a/Inputs/Keyboard.hpp b/Inputs/Keyboard.hpp
index 924526ce9..56105b279 100644
--- a/Inputs/Keyboard.hpp
+++ b/Inputs/Keyboard.hpp
@@ -53,10 +53,10 @@ class Keyboard {
 		virtual void reset_all_keys();
 
 		/// @returns a set of all Keys that this keyboard responds to.
-		virtual const std::set<Key> &observed_keys();
+		virtual const std::set<Key> &observed_keys() const;
 
 		/// @returns the list of modifiers that this keyboard considers 'essential' (i.e. both mapped and highly used).
-		virtual const std::set<Inputs::Keyboard::Key> &get_essential_modifiers();
+		virtual const std::set<Inputs::Keyboard::Key> &get_essential_modifiers() const;
 
 		/*!
 			@returns @c true if this keyboard, on its original machine, looked
@@ -68,7 +68,7 @@ class Keyboard {
 			which has some buttons that you'd expect an emulator to map to its host
 			keyboard but which does not offer a full keyboard.
 		*/
-		virtual bool is_exclusive();
+		virtual bool is_exclusive() const;
 
 		// Delegate interface.
 		struct Delegate {
@@ -76,7 +76,7 @@ class Keyboard {
 			virtual void reset_all_keys(Keyboard *keyboard) = 0;
 		};
 		void set_delegate(Delegate *delegate);
-		bool get_key_state(Key key);
+		bool get_key_state(Key key) const;
 
 	private:
 		std::set<Key> observed_keys_;
diff --git a/Inputs/QuadratureMouse/QuadratureMouse.hpp b/Inputs/QuadratureMouse/QuadratureMouse.hpp
index e3ba34d6b..b1b596a79 100644
--- a/Inputs/QuadratureMouse/QuadratureMouse.hpp
+++ b/Inputs/QuadratureMouse/QuadratureMouse.hpp
@@ -111,8 +111,8 @@ class QuadratureMouse: public Mouse {
 
 	private:
 		const int number_of_buttons_ = 0;
-		std::atomic<int> button_flags_;
-		std::atomic<int> axes_[2];
+		std::atomic<int> button_flags_{0};
+		std::atomic<int> axes_[2]{0, 0};
 
 		int primaries_[2] = {0, 0};
 		int secondaries_[2] = {0, 0};
diff --git a/Machines/AmstradCPC/AmstradCPC.cpp b/Machines/AmstradCPC/AmstradCPC.cpp
index 1d4db3b8c..e05d92b95 100644
--- a/Machines/AmstradCPC/AmstradCPC.cpp
+++ b/Machines/AmstradCPC/AmstradCPC.cpp
@@ -346,7 +346,7 @@ class CRTCBusHandler {
 		}
 
 		/// Gets the type of display.
-		Outputs::Display::DisplayType get_display_type() {
+		Outputs::Display::DisplayType get_display_type() const {
 			return crt_.get_display_type();
 		}
 
@@ -1044,7 +1044,7 @@ template <bool has_fdc> class ConcreteMachine:
 		}
 
 		/// A CRTMachine function; gets the output display type.
-		Outputs::Display::DisplayType get_display_type() {
+		Outputs::Display::DisplayType get_display_type() const final {
 			return crtc_bus_handler_.get_display_type();
 		}
 
@@ -1085,15 +1085,15 @@ template <bool has_fdc> class ConcreteMachine:
 			Utility::TypeRecipient<CharacterMapper>::add_typer(string);
 		}
 
-		bool can_type(char c) final {
+		bool can_type(char c) const final {
 			return Utility::TypeRecipient<CharacterMapper>::can_type(c);
 		}
 
-		HalfCycles get_typer_delay() final {
+		HalfCycles get_typer_delay() const final {
 			return z80_.get_is_resetting() ? Cycles(3'400'000) : Cycles(0);
 		}
 
-		HalfCycles get_typer_frequency() final {
+		HalfCycles get_typer_frequency() const final {
 			return Cycles(80'000);	// Perform one key transition per frame.
 		}
 
diff --git a/Machines/AmstradCPC/Keyboard.cpp b/Machines/AmstradCPC/Keyboard.cpp
index 21aee331b..98b67e8ae 100644
--- a/Machines/AmstradCPC/Keyboard.cpp
+++ b/Machines/AmstradCPC/Keyboard.cpp
@@ -10,7 +10,7 @@
 
 using namespace AmstradCPC;
 
-uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
+uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) const {
 #define BIND(source, dest)	case Inputs::Keyboard::Key::source:	return dest
 	switch(key) {
 		default: break;
@@ -77,7 +77,7 @@ uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
 	return MachineTypes::MappedKeyboardMachine::KeyNotMapped;
 }
 
-uint16_t *CharacterMapper::sequence_for_character(char character) {
+const uint16_t *CharacterMapper::sequence_for_character(char character) const {
 #define KEYS(...)	{__VA_ARGS__, MachineTypes::MappedKeyboardMachine::KeyEndSequence}
 #define SHIFT(...)	{KeyShift, __VA_ARGS__, MachineTypes::MappedKeyboardMachine::KeyEndSequence}
 #define X			{MachineTypes::MappedKeyboardMachine::KeyNotMapped}
@@ -154,6 +154,6 @@ uint16_t *CharacterMapper::sequence_for_character(char character) {
 	return table_lookup_sequence_for_character(key_sequences, sizeof(key_sequences), character);
 }
 
-bool CharacterMapper::needs_pause_after_key(uint16_t key) {
+bool CharacterMapper::needs_pause_after_key(uint16_t key) const {
 	return key != KeyControl && key != KeyShift;
 }
diff --git a/Machines/AmstradCPC/Keyboard.hpp b/Machines/AmstradCPC/Keyboard.hpp
index b477b618a..120dbc394 100644
--- a/Machines/AmstradCPC/Keyboard.hpp
+++ b/Machines/AmstradCPC/Keyboard.hpp
@@ -34,14 +34,14 @@ enum Key: uint16_t {
 };
 
 struct KeyboardMapper: public MachineTypes::MappedKeyboardMachine::KeyboardMapper {
-	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key);
+	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key) const override;
 };
 
 struct CharacterMapper: public ::Utility::CharacterMapper {
-	uint16_t *sequence_for_character(char character) override;
+	const uint16_t *sequence_for_character(char character) const override;
 
-	bool needs_pause_after_reset_all_keys() override	{ return false; }
-	bool needs_pause_after_key(uint16_t key) override;
+	bool needs_pause_after_reset_all_keys() const override	{ return false; }
+	bool needs_pause_after_key(uint16_t key) const override;
 };
 
 };
diff --git a/Machines/Apple/AppleII/AppleII.cpp b/Machines/Apple/AppleII/AppleII.cpp
index b3f1b2905..e57fca73a 100644
--- a/Machines/Apple/AppleII/AppleII.cpp
+++ b/Machines/Apple/AppleII/AppleII.cpp
@@ -423,7 +423,7 @@ template <Analyser::Static::AppleII::Target::Model model> class ConcreteMachine:
 			video_.set_display_type(display_type);
 		}
 
-		Outputs::Display::DisplayType get_display_type() final {
+		Outputs::Display::DisplayType get_display_type() const final {
 			return video_.get_display_type();
 		}
 
@@ -857,7 +857,7 @@ template <Analyser::Static::AppleII::Target::Model model> class ConcreteMachine:
 			string_serialiser_ = std::make_unique<Utility::StringSerialiser>(string, true);
 		}
 
-		bool can_type(char c) final {
+		bool can_type(char c) const final {
 			// Make an effort to type the entire printable ASCII range.
 			return c >= 32 && c < 127;
 		}
diff --git a/Machines/Apple/AppleII/Video.cpp b/Machines/Apple/AppleII/Video.cpp
index 70aa02b8c..c249b3540 100644
--- a/Machines/Apple/AppleII/Video.cpp
+++ b/Machines/Apple/AppleII/Video.cpp
@@ -55,7 +55,7 @@ void VideoBase::set_display_type(Outputs::Display::DisplayType display_type) {
 	crt_.set_display_type(display_type);
 }
 
-Outputs::Display::DisplayType VideoBase::get_display_type() {
+Outputs::Display::DisplayType VideoBase::get_display_type() const {
 	return crt_.get_display_type();
 }
 
diff --git a/Machines/Apple/AppleII/Video.hpp b/Machines/Apple/AppleII/Video.hpp
index 4f2623d14..07297222e 100644
--- a/Machines/Apple/AppleII/Video.hpp
+++ b/Machines/Apple/AppleII/Video.hpp
@@ -47,7 +47,7 @@ class VideoBase {
 		void set_display_type(Outputs::Display::DisplayType);
 
 		/// Gets the type of output.
-		Outputs::Display::DisplayType get_display_type();
+		Outputs::Display::DisplayType get_display_type() const;
 
 		/*
 			Descriptions for the setters below are taken verbatim from
diff --git a/Machines/Apple/Macintosh/Keyboard.cpp b/Machines/Apple/Macintosh/Keyboard.cpp
index c1c5a5ae6..e9631857f 100644
--- a/Machines/Apple/Macintosh/Keyboard.cpp
+++ b/Machines/Apple/Macintosh/Keyboard.cpp
@@ -10,7 +10,7 @@
 
 using namespace Apple::Macintosh;
 
-uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
+uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) const {
 	using Key = Inputs::Keyboard::Key;
 	using MacKey = Apple::Macintosh::Key;
 	switch(key) {
diff --git a/Machines/Apple/Macintosh/Keyboard.hpp b/Machines/Apple/Macintosh/Keyboard.hpp
index 158776991..241fef658 100644
--- a/Machines/Apple/Macintosh/Keyboard.hpp
+++ b/Machines/Apple/Macintosh/Keyboard.hpp
@@ -291,7 +291,7 @@ class Keyboard {
 	Provides a mapping from idiomatic PC keys to Macintosh keys.
 */
 class KeyboardMapper: public MachineTypes::MappedKeyboardMachine::KeyboardMapper {
-	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key) final;
+	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key) const final;
 };
 
 }
diff --git a/Machines/Atari/ST/AtariST.cpp b/Machines/Atari/ST/AtariST.cpp
index fa566ba04..722604358 100644
--- a/Machines/Atari/ST/AtariST.cpp
+++ b/Machines/Atari/ST/AtariST.cpp
@@ -141,7 +141,7 @@ class ConcreteMachine:
 			video_->set_display_type(display_type);
 		}
 
-		Outputs::Display::DisplayType get_display_type() final {
+		Outputs::Display::DisplayType get_display_type() const final {
 			return video_->get_display_type();
 		}
 
diff --git a/Machines/Atari/ST/IntelligentKeyboard.cpp b/Machines/Atari/ST/IntelligentKeyboard.cpp
index 06f848778..a1f325b9c 100644
--- a/Machines/Atari/ST/IntelligentKeyboard.cpp
+++ b/Machines/Atari/ST/IntelligentKeyboard.cpp
@@ -22,11 +22,6 @@ IntelligentKeyboard::IntelligentKeyboard(Serial::Line &input, Serial::Line &outp
 	// Add two joysticks into the mix.
 	joysticks_.emplace_back(new Joystick);
 	joysticks_.emplace_back(new Joystick);
-
-	mouse_button_state_ = 0;
-	mouse_button_events_ = 0;
-	mouse_movement_[0] = 0;
-	mouse_movement_[1] = 0;
 }
 
 bool IntelligentKeyboard::serial_line_did_produce_bit(Serial::Line *, int bit) {
@@ -361,7 +356,7 @@ void IntelligentKeyboard::set_key_state(Key key, bool is_pressed) {
 	}
 }
 
-uint16_t IntelligentKeyboard::KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
+uint16_t IntelligentKeyboard::KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) const {
 	using Key = Inputs::Keyboard::Key;
 	using STKey = Atari::ST::Key;
 	switch(key) {
diff --git a/Machines/Atari/ST/IntelligentKeyboard.hpp b/Machines/Atari/ST/IntelligentKeyboard.hpp
index 54b6d0560..fb96045e6 100644
--- a/Machines/Atari/ST/IntelligentKeyboard.hpp
+++ b/Machines/Atari/ST/IntelligentKeyboard.hpp
@@ -63,7 +63,7 @@ class IntelligentKeyboard:
 
 		void set_key_state(Key key, bool is_pressed);
 		class KeyboardMapper: public MachineTypes::MappedKeyboardMachine::KeyboardMapper {
-			uint16_t mapped_key_for_key(Inputs::Keyboard::Key key) final;
+			uint16_t mapped_key_for_key(Inputs::Keyboard::Key key) const final;
 		};
 
 		const std::vector<std::unique_ptr<Inputs::Joystick>> &get_joysticks() {
@@ -127,9 +127,9 @@ class IntelligentKeyboard:
 		void post_relative_mouse_event(int x, int y);
 
 		// Received mouse state.
-		std::atomic<int> mouse_movement_[2];
-		std::atomic<int> mouse_button_state_;
-		std::atomic<int> mouse_button_events_;
+		std::atomic<int> mouse_movement_[2]{0, 0};
+		std::atomic<int> mouse_button_state_{0};
+		std::atomic<int> mouse_button_events_{0};
 
 		// MARK: - Joystick.
 		void disable_joysticks();
diff --git a/Machines/Atari/ST/Video.cpp b/Machines/Atari/ST/Video.cpp
index 5c3ba851f..5a12ff781 100644
--- a/Machines/Atari/ST/Video.cpp
+++ b/Machines/Atari/ST/Video.cpp
@@ -146,7 +146,7 @@ void Video::set_display_type(Outputs::Display::DisplayType display_type) {
 	crt_.set_display_type(display_type);
 }
 
-Outputs::Display::DisplayType Video::get_display_type() {
+Outputs::Display::DisplayType Video::get_display_type() const {
 	return crt_.get_display_type();
 }
 
diff --git a/Machines/Atari/ST/Video.hpp b/Machines/Atari/ST/Video.hpp
index 851d8674c..867d6c632 100644
--- a/Machines/Atari/ST/Video.hpp
+++ b/Machines/Atari/ST/Video.hpp
@@ -57,7 +57,7 @@ class Video {
 		/*!
 			Gets the type of output.
 		*/
-		Outputs::Display::DisplayType get_display_type();
+		Outputs::Display::DisplayType get_display_type() const;
 
 		/*!
 			Produces the next @c duration period of pixels.
diff --git a/Machines/ColecoVision/ColecoVision.cpp b/Machines/ColecoVision/ColecoVision.cpp
index 5660723ac..0de8f56d0 100644
--- a/Machines/ColecoVision/ColecoVision.cpp
+++ b/Machines/ColecoVision/ColecoVision.cpp
@@ -189,7 +189,7 @@ class ConcreteMachine:
 			vdp_->set_display_type(display_type);
 		}
 
-		Outputs::Display::DisplayType get_display_type() final {
+		Outputs::Display::DisplayType get_display_type() const final {
 			return vdp_->get_display_type();
 		}
 
diff --git a/Machines/Commodore/Vic-20/Keyboard.cpp b/Machines/Commodore/Vic-20/Keyboard.cpp
index edcb75c87..1b79bd414 100644
--- a/Machines/Commodore/Vic-20/Keyboard.cpp
+++ b/Machines/Commodore/Vic-20/Keyboard.cpp
@@ -10,7 +10,7 @@
 
 using namespace Commodore::Vic20;
 
-uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
+uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) const {
 #define BIND(source, dest)	case Inputs::Keyboard::Key::source:	return Commodore::Vic20::dest
 	switch(key) {
 		default: break;
@@ -79,7 +79,7 @@ uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
 	return MachineTypes::MappedKeyboardMachine::KeyNotMapped;
 }
 
-uint16_t *CharacterMapper::sequence_for_character(char character) {
+const uint16_t *CharacterMapper::sequence_for_character(char character) const {
 #define KEYS(...)	{__VA_ARGS__, MachineTypes::MappedKeyboardMachine::KeyEndSequence}
 #define SHIFT(...)	{KeyLShift, __VA_ARGS__, MachineTypes::MappedKeyboardMachine::KeyEndSequence}
 #define X			{MachineTypes::MappedKeyboardMachine::KeyNotMapped}
diff --git a/Machines/Commodore/Vic-20/Keyboard.hpp b/Machines/Commodore/Vic-20/Keyboard.hpp
index 84d54c6dd..cfe7f8a8b 100644
--- a/Machines/Commodore/Vic-20/Keyboard.hpp
+++ b/Machines/Commodore/Vic-20/Keyboard.hpp
@@ -48,11 +48,11 @@ enum Key: uint16_t {
 };
 
 struct KeyboardMapper: public MachineTypes::MappedKeyboardMachine::KeyboardMapper {
-	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key);
+	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key) const final;
 };
 
 struct CharacterMapper: public ::Utility::CharacterMapper {
-	uint16_t *sequence_for_character(char character);
+	const uint16_t *sequence_for_character(char character) const final;
 };
 
 }
diff --git a/Machines/Commodore/Vic-20/Vic20.cpp b/Machines/Commodore/Vic-20/Vic20.cpp
index 2df232ed4..9630f2dd4 100644
--- a/Machines/Commodore/Vic-20/Vic20.cpp
+++ b/Machines/Commodore/Vic-20/Vic20.cpp
@@ -646,7 +646,7 @@ class ConcreteMachine:
 			mos6560_.set_display_type(display_type);
 		}
 
-		Outputs::Display::DisplayType get_display_type() final {
+		Outputs::Display::DisplayType get_display_type() const final {
 			return mos6560_.get_display_type();
 		}
 
@@ -663,7 +663,7 @@ class ConcreteMachine:
 			Utility::TypeRecipient<CharacterMapper>::add_typer(string);
 		}
 
-		bool can_type(char c) final {
+		bool can_type(char c) const final {
 			return Utility::TypeRecipient<CharacterMapper>::can_type(c);
 		}
 
diff --git a/Machines/Electron/Electron.cpp b/Machines/Electron/Electron.cpp
index c987172d3..39251917f 100644
--- a/Machines/Electron/Electron.cpp
+++ b/Machines/Electron/Electron.cpp
@@ -409,7 +409,7 @@ class ConcreteMachine:
 			video_output_.set_display_type(display_type);
 		}
 
-		Outputs::Display::DisplayType get_display_type() final {
+		Outputs::Display::DisplayType get_display_type() const final {
 			return video_output_.get_display_type();
 		}
 
@@ -426,11 +426,11 @@ class ConcreteMachine:
 			evaluate_interrupts();
 		}
 
-		HalfCycles get_typer_delay() final {
+		HalfCycles get_typer_delay() const final {
 			return m6502_.get_is_resetting() ? Cycles(750'000) : Cycles(0);
 		}
 
-		HalfCycles get_typer_frequency() final {
+		HalfCycles get_typer_frequency() const final {
 			return Cycles(60'000);
 		}
 
@@ -438,7 +438,7 @@ class ConcreteMachine:
 			Utility::TypeRecipient<CharacterMapper>::add_typer(string);
 		}
 
-		bool can_type(char c) final {
+		bool can_type(char c) const final {
 			return Utility::TypeRecipient<CharacterMapper>::can_type(c);
 		}
 
diff --git a/Machines/Electron/Keyboard.cpp b/Machines/Electron/Keyboard.cpp
index e09125dad..887ac5aff 100644
--- a/Machines/Electron/Keyboard.cpp
+++ b/Machines/Electron/Keyboard.cpp
@@ -10,7 +10,7 @@
 
 using namespace Electron;
 
-uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
+uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) const {
 #define BIND(source, dest)	case Inputs::Keyboard::Key::source:	return Electron::Key::dest
 	switch(key) {
 		default: break;
@@ -69,7 +69,7 @@ uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
 	return MachineTypes::MappedKeyboardMachine::KeyNotMapped;
 }
 
-uint16_t *CharacterMapper::sequence_for_character(char character) {
+const uint16_t *CharacterMapper::sequence_for_character(char character) const {
 #define KEYS(...)	{__VA_ARGS__, MachineTypes::MappedKeyboardMachine::KeyEndSequence}
 #define SHIFT(...)	{KeyShift, __VA_ARGS__, MachineTypes::MappedKeyboardMachine::KeyEndSequence}
 #define CTRL(...)	{KeyControl, __VA_ARGS__, MachineTypes::MappedKeyboardMachine::KeyEndSequence}
@@ -147,6 +147,6 @@ uint16_t *CharacterMapper::sequence_for_character(char character) {
 	return table_lookup_sequence_for_character(key_sequences, sizeof(key_sequences), character);
 }
 
-bool CharacterMapper::needs_pause_after_key(uint16_t key) {
+bool CharacterMapper::needs_pause_after_key(uint16_t key) const {
 	return key != KeyControl && key != KeyShift && key != KeyFunc;
 }
diff --git a/Machines/Electron/Keyboard.hpp b/Machines/Electron/Keyboard.hpp
index 7b95e8967..d41f6500c 100644
--- a/Machines/Electron/Keyboard.hpp
+++ b/Machines/Electron/Keyboard.hpp
@@ -37,14 +37,14 @@ enum Key: uint16_t {
 };
 
 struct KeyboardMapper: public MachineTypes::MappedKeyboardMachine::KeyboardMapper {
-	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key) final;
+	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key) const final;
 };
 
 struct CharacterMapper: public ::Utility::CharacterMapper {
-	uint16_t *sequence_for_character(char character) override;
+	const uint16_t *sequence_for_character(char character) const override;
 
-	bool needs_pause_after_reset_all_keys() override	{ return false; }
-	bool needs_pause_after_key(uint16_t key) override;
+	bool needs_pause_after_reset_all_keys() const override	{ return false; }
+	bool needs_pause_after_key(uint16_t key) const override;
 };
 
 };
diff --git a/Machines/Electron/Video.cpp b/Machines/Electron/Video.cpp
index 7cc20fcf7..461057ebf 100644
--- a/Machines/Electron/Video.cpp
+++ b/Machines/Electron/Video.cpp
@@ -64,7 +64,7 @@ void VideoOutput::set_display_type(Outputs::Display::DisplayType display_type) {
 	crt_.set_display_type(display_type);
 }
 
-Outputs::Display::DisplayType VideoOutput::get_display_type() {
+Outputs::Display::DisplayType VideoOutput::get_display_type() const {
 	return crt_.get_display_type();
 }
 
diff --git a/Machines/Electron/Video.hpp b/Machines/Electron/Video.hpp
index aa2b28dec..137dca0e0 100644
--- a/Machines/Electron/Video.hpp
+++ b/Machines/Electron/Video.hpp
@@ -46,7 +46,7 @@ class VideoOutput {
 		void set_display_type(Outputs::Display::DisplayType);
 
 		/// Gets the type of output.
-		Outputs::Display::DisplayType get_display_type();
+		Outputs::Display::DisplayType get_display_type() const;
 
 		/*!
 			Writes @c value to the register at @c address. May mutate the results of @c get_next_interrupt,
diff --git a/Machines/KeyboardMachine.hpp b/Machines/KeyboardMachine.hpp
index bd90ded02..1ef6fcec0 100644
--- a/Machines/KeyboardMachine.hpp
+++ b/Machines/KeyboardMachine.hpp
@@ -49,7 +49,7 @@ class KeyboardMachine: public KeyActions {
 		/*!
 			@returns @c true if this machine can type the character @c c as part of a @c type_string; @c false otherwise.
 		*/
-		virtual bool can_type(char c) { return false; }
+		virtual bool can_type(char c) const { return false; }
 
 		/*!
 			Provides a destination for keyboard input.
@@ -117,7 +117,7 @@ class MappedKeyboardMachine: public Inputs::Keyboard::Delegate, public KeyboardM
 		*/
 		class KeyboardMapper {
 			public:
-				virtual uint16_t mapped_key_for_key(Inputs::Keyboard::Key key) = 0;
+				virtual uint16_t mapped_key_for_key(Inputs::Keyboard::Key key) const = 0;
 		};
 
 		/// Terminates a key sequence from the character mapper.
diff --git a/Machines/MSX/Keyboard.cpp b/Machines/MSX/Keyboard.cpp
index 2ca15e306..494ab6232 100644
--- a/Machines/MSX/Keyboard.cpp
+++ b/Machines/MSX/Keyboard.cpp
@@ -8,7 +8,7 @@
 
 #include "Keyboard.hpp"
 
-uint16_t MSX::KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
+uint16_t MSX::KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) const {
 #define BIND(source, dest)	case Inputs::Keyboard::Key::source:	return MSX::Key::dest
 	switch(key) {
 		BIND(k0, Key0);		BIND(k1, Key1);		BIND(k2, Key2);		BIND(k3, Key3);		BIND(k4, Key4);
diff --git a/Machines/MSX/Keyboard.hpp b/Machines/MSX/Keyboard.hpp
index 07fd35526..445a1a1f0 100644
--- a/Machines/MSX/Keyboard.hpp
+++ b/Machines/MSX/Keyboard.hpp
@@ -34,7 +34,7 @@ enum Key: uint16_t {
 };
 
 struct KeyboardMapper: public MachineTypes::MappedKeyboardMachine::KeyboardMapper {
-	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key);
+	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key) const final;
 };
 
 };
diff --git a/Machines/MSX/MSX.cpp b/Machines/MSX/MSX.cpp
index faabc8142..2bd9ee16c 100644
--- a/Machines/MSX/MSX.cpp
+++ b/Machines/MSX/MSX.cpp
@@ -284,7 +284,7 @@ class ConcreteMachine:
 			vdp_->set_display_type(display_type);
 		}
 
-		Outputs::Display::DisplayType get_display_type() final {
+		Outputs::Display::DisplayType get_display_type() const final {
 			return vdp_->get_display_type();
 		}
 
@@ -367,7 +367,7 @@ class ConcreteMachine:
 			);
 		}
 
-		bool can_type(char c) final {
+		bool can_type(char c) const final {
 			// Make an effort to type the entire printable ASCII range.
 			return c >= 32 && c < 127;
 		}
diff --git a/Machines/MasterSystem/MasterSystem.cpp b/Machines/MasterSystem/MasterSystem.cpp
index 7d40dea1d..f43e999ea 100644
--- a/Machines/MasterSystem/MasterSystem.cpp
+++ b/Machines/MasterSystem/MasterSystem.cpp
@@ -201,7 +201,7 @@ class ConcreteMachine:
 			vdp_->set_display_type(display_type);
 		}
 
-		Outputs::Display::DisplayType get_display_type() final {
+		Outputs::Display::DisplayType get_display_type() const final {
 			return vdp_->get_display_type();
 		}
 
diff --git a/Machines/Oric/Keyboard.cpp b/Machines/Oric/Keyboard.cpp
index 40661448e..2e373ad57 100644
--- a/Machines/Oric/Keyboard.cpp
+++ b/Machines/Oric/Keyboard.cpp
@@ -10,7 +10,7 @@
 
 using namespace Oric;
 
-uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
+uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) const {
 #define BIND(source, dest)	case Inputs::Keyboard::Key::source:	return Oric::dest
 	switch(key) {
 		default: break;
@@ -54,7 +54,7 @@ uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
 	return MachineTypes::MappedKeyboardMachine::KeyNotMapped;
 }
 
-uint16_t *CharacterMapper::sequence_for_character(char character) {
+const uint16_t *CharacterMapper::sequence_for_character(char character) const {
 #define KEYS(...)	{__VA_ARGS__, MachineTypes::MappedKeyboardMachine::KeyEndSequence}
 #define SHIFT(...)	{KeyLeftShift, __VA_ARGS__, MachineTypes::MappedKeyboardMachine::KeyEndSequence}
 #define X			{MachineTypes::MappedKeyboardMachine::KeyNotMapped}
diff --git a/Machines/Oric/Keyboard.hpp b/Machines/Oric/Keyboard.hpp
index 87c20d1c1..d40fd0abf 100644
--- a/Machines/Oric/Keyboard.hpp
+++ b/Machines/Oric/Keyboard.hpp
@@ -37,11 +37,11 @@ enum Key: uint16_t {
 };
 
 struct KeyboardMapper: public MachineTypes::MappedKeyboardMachine::KeyboardMapper {
-	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key);
+	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key) const final;
 };
 
 struct CharacterMapper: public ::Utility::CharacterMapper {
-	uint16_t *sequence_for_character(char character);
+	const uint16_t *sequence_for_character(char character) const final;
 };
 
 };
diff --git a/Machines/Oric/Oric.cpp b/Machines/Oric/Oric.cpp
index 05d78197e..e336148a0 100644
--- a/Machines/Oric/Oric.cpp
+++ b/Machines/Oric/Oric.cpp
@@ -555,7 +555,7 @@ template <Analyser::Static::Oric::Target::DiskInterface disk_interface> class Co
 			video_output_.set_display_type(display_type);
 		}
 
-		Outputs::Display::DisplayType get_display_type() final {
+		Outputs::Display::DisplayType get_display_type() const final {
 			return video_output_.get_display_type();
 		}
 
@@ -583,7 +583,7 @@ template <Analyser::Static::Oric::Target::DiskInterface disk_interface> class Co
 			string_serialiser_ = std::make_unique<Utility::StringSerialiser>(string, true);
 		}
 
-		bool can_type(char c) final {
+		bool can_type(char c) const final {
 			// Make an effort to type the entire printable ASCII range.
 			return c >= 32 && c < 127;
 		}
diff --git a/Machines/Oric/Video.cpp b/Machines/Oric/Video.cpp
index 8bbc8563a..30fe2f805 100644
--- a/Machines/Oric/Video.cpp
+++ b/Machines/Oric/Video.cpp
@@ -67,7 +67,7 @@ void VideoOutput::set_display_type(Outputs::Display::DisplayType display_type) {
 	}
 }
 
-Outputs::Display::DisplayType VideoOutput::get_display_type() {
+Outputs::Display::DisplayType VideoOutput::get_display_type() const {
 	return crt_.get_display_type();
 }
 
diff --git a/Machines/Oric/Video.hpp b/Machines/Oric/Video.hpp
index fe3001efe..59181526d 100644
--- a/Machines/Oric/Video.hpp
+++ b/Machines/Oric/Video.hpp
@@ -27,7 +27,7 @@ class VideoOutput {
 
 		void set_scan_target(Outputs::Display::ScanTarget *scan_target);
 		void set_display_type(Outputs::Display::DisplayType display_type);
-		Outputs::Display::DisplayType get_display_type();
+		Outputs::Display::DisplayType get_display_type() const;
 		Outputs::Display::ScanStatus get_scaled_scan_status() const;
 
 		void register_crt_frequency_mismatch();
diff --git a/Machines/ScanProducer.hpp b/Machines/ScanProducer.hpp
index 4393086e1..3fbf95839 100644
--- a/Machines/ScanProducer.hpp
+++ b/Machines/ScanProducer.hpp
@@ -78,7 +78,7 @@ class ScanProducer {
 			Maps back from Outputs::Display::VideoSignal  to Configurable::Display,
 			calling @c get_display_type for the input.
 		*/
-		Configurable::Display get_video_signal_configurable() {
+		Configurable::Display get_video_signal_configurable() const {
 			switch(get_display_type()) {
 				default:
 				case Outputs::Display::DisplayType::RGB:					return Configurable::Display::RGB;
@@ -96,7 +96,7 @@ class ScanProducer {
 		/*!
 			Gets the display type.
 		*/
-		virtual Outputs::Display::DisplayType get_display_type() { return Outputs::Display::DisplayType::RGB; }
+		virtual Outputs::Display::DisplayType get_display_type() const { return Outputs::Display::DisplayType::RGB; }
 };
 
 }
diff --git a/Machines/Utility/Typer.cpp b/Machines/Utility/Typer.cpp
index 824f8278a..4470f97c2 100644
--- a/Machines/Utility/Typer.cpp
+++ b/Machines/Utility/Typer.cpp
@@ -134,7 +134,7 @@ bool Typer::type_next_character() {
 
 // MARK: - Character mapper
 
-uint16_t *CharacterMapper::table_lookup_sequence_for_character(KeySequence *sequences, std::size_t length, char character) {
+uint16_t *CharacterMapper::table_lookup_sequence_for_character(KeySequence *sequences, std::size_t length, char character) const {
 	std::size_t ucharacter = size_t((unsigned char)character);
 	if(ucharacter >= (length / sizeof(KeySequence))) return nullptr;
 	if(sequences[ucharacter][0] == MachineTypes::MappedKeyboardMachine::KeyNotMapped) return nullptr;
diff --git a/Machines/Utility/Typer.hpp b/Machines/Utility/Typer.hpp
index 8f73b8c99..0e2ed9ef1 100644
--- a/Machines/Utility/Typer.hpp
+++ b/Machines/Utility/Typer.hpp
@@ -26,19 +26,19 @@ class CharacterMapper {
 		virtual ~CharacterMapper() {}
 
 		/// @returns The EndSequence-terminated sequence of keys that would cause @c character to be typed.
-		virtual uint16_t *sequence_for_character(char character) = 0;
+		virtual const uint16_t *sequence_for_character(char character) const = 0;
 
 		/// The typer will automatically reset all keys in between each sequence that it types.
 		/// By default it will pause for one key's duration when doing so. Character mappers
 		/// can eliminate that pause by overriding this method.
 		/// @returns @c true if the typer should pause after performing a reset; @c false otherwise.
-		virtual bool needs_pause_after_reset_all_keys()	{ return true; }
+		virtual bool needs_pause_after_reset_all_keys() const	{ return true; }
 
 		/// The typer will pause between every entry in a keyboard sequence. On some machines
 		/// that may not be necessary — it'll often depends on whether the machine needs time to
 		/// observe a modifier like shift before it sees the actual keypress.
 		/// @returns @c true if the typer should pause after forwarding @c key; @c false otherwise.
-		virtual bool needs_pause_after_key(uint16_t key)	{ return true; }
+		virtual bool needs_pause_after_key(uint16_t key) const	{ return true; }
 
 	protected:
 		typedef uint16_t KeySequence[16];
@@ -48,7 +48,7 @@ class CharacterMapper {
 			with @c length entries, returns the sequence for character @c character if it exists; otherwise
 			returns @c nullptr.
 		*/
-		uint16_t *table_lookup_sequence_for_character(KeySequence *sequences, std::size_t length, char character);
+		uint16_t *table_lookup_sequence_for_character(KeySequence *sequences, std::size_t length, char character) const;
 };
 
 /*!
@@ -118,7 +118,7 @@ class TypeRecipient: public Typer::Delegate {
 		/*!
 			@returns @c true if the character mapper provides a mapping for @c c; @c false otherwise.
 		*/
-		bool can_type(char c) {
+		bool can_type(char c) const {
 			const auto sequence = character_mapper.sequence_for_character(c);
 			return sequence && sequence[0] != MachineTypes::MappedKeyboardMachine::KeyNotMapped;
 		}
@@ -137,8 +137,8 @@ class TypeRecipient: public Typer::Delegate {
 			typer_ = nullptr;
 		}
 
-		virtual HalfCycles get_typer_delay() { return HalfCycles(0); }
-		virtual HalfCycles get_typer_frequency() { return HalfCycles(0); }
+		virtual HalfCycles get_typer_delay() const { return HalfCycles(0); }
+		virtual HalfCycles get_typer_frequency() const { return HalfCycles(0); }
 		std::unique_ptr<Typer> typer_;
 
 	private:
diff --git a/Machines/ZX8081/Keyboard.cpp b/Machines/ZX8081/Keyboard.cpp
index d4e2a5e4a..d3e25f381 100644
--- a/Machines/ZX8081/Keyboard.cpp
+++ b/Machines/ZX8081/Keyboard.cpp
@@ -10,7 +10,7 @@
 
 using namespace ZX8081;
 
-uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
+uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) const {
 #define BIND(source, dest)	case Inputs::Keyboard::Key::source:	return ZX8081::dest
 	switch(key) {
 		default: break;
@@ -44,7 +44,7 @@ uint16_t KeyboardMapper::mapped_key_for_key(Inputs::Keyboard::Key key) {
 
 CharacterMapper::CharacterMapper(bool is_zx81) : is_zx81_(is_zx81) {}
 
-uint16_t *CharacterMapper::sequence_for_character(char character) {
+const uint16_t *CharacterMapper::sequence_for_character(char character) const {
 #define KEYS(...)	{__VA_ARGS__, MachineTypes::MappedKeyboardMachine::KeyEndSequence}
 #define SHIFT(...)	{KeyShift, __VA_ARGS__, MachineTypes::MappedKeyboardMachine::KeyEndSequence}
 #define X			{MachineTypes::MappedKeyboardMachine::KeyNotMapped}
@@ -189,6 +189,6 @@ uint16_t *CharacterMapper::sequence_for_character(char character) {
 		return table_lookup_sequence_for_character(zx80_key_sequences, sizeof(zx80_key_sequences), character);
 }
 
-bool CharacterMapper::needs_pause_after_key(uint16_t key) {
+bool CharacterMapper::needs_pause_after_key(uint16_t key) const {
 	return key != KeyShift;
 }
diff --git a/Machines/ZX8081/Keyboard.hpp b/Machines/ZX8081/Keyboard.hpp
index d4f930bf2..56cb848ad 100644
--- a/Machines/ZX8081/Keyboard.hpp
+++ b/Machines/ZX8081/Keyboard.hpp
@@ -30,15 +30,15 @@ enum Key: uint16_t {
 };
 
 struct KeyboardMapper: public MachineTypes::MappedKeyboardMachine::KeyboardMapper {
-	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key);
+	uint16_t mapped_key_for_key(Inputs::Keyboard::Key key) const override;
 };
 
 class CharacterMapper: public ::Utility::CharacterMapper {
 	public:
 		CharacterMapper(bool is_zx81);
-		uint16_t *sequence_for_character(char character) override;
+		const uint16_t *sequence_for_character(char character) const override;
 
-		bool needs_pause_after_key(uint16_t key) override;
+		bool needs_pause_after_key(uint16_t key) const override;
 
 	private:
 		bool is_zx81_;
diff --git a/Machines/ZX8081/ZX8081.cpp b/Machines/ZX8081/ZX8081.cpp
index ec5b7cf8b..6108ef28a 100644
--- a/Machines/ZX8081/ZX8081.cpp
+++ b/Machines/ZX8081/ZX8081.cpp
@@ -337,7 +337,7 @@ template<bool is_zx81> class ConcreteMachine:
 			Utility::TypeRecipient<CharacterMapper>::add_typer(string);
 		}
 
-		bool can_type(char c) final {
+		bool can_type(char c) const final {
 			return Utility::TypeRecipient<CharacterMapper>::can_type(c);
 		}
 
@@ -393,11 +393,11 @@ template<bool is_zx81> class ConcreteMachine:
 		}
 
 		// MARK: - Typer timing
-		HalfCycles get_typer_delay() final {
+		HalfCycles get_typer_delay() const final {
 			return z80_.get_is_resetting() ? Cycles(7'000'000) : Cycles(0);
 		}
 
-		HalfCycles get_typer_frequency() final {
+		HalfCycles get_typer_frequency() const final {
 			return Cycles(146'250);
 		}
 
diff --git a/Numeric/CRC.hpp b/Numeric/CRC.hpp
index 1ae096b7d..9e10c9a41 100644
--- a/Numeric/CRC.hpp
+++ b/Numeric/CRC.hpp
@@ -21,7 +21,7 @@ template <typename IntType, IntType reset_value, IntType output_xor, bool reflec
 			Instantiates a CRC16 that will compute the CRC16 specified by the supplied
 			@c polynomial and @c reset_value.
 		*/
-		Generator(IntType polynomial): value_(reset_value) {
+		constexpr Generator(IntType polynomial) noexcept: value_(reset_value) {
 			const IntType top_bit = IntType(~(IntType(~0) >> 1));
 			for(int c = 0; c < 256; c++) {
 				IntType shift_value = IntType(c << multibyte_shift);
diff --git a/Numeric/LFSR.hpp b/Numeric/LFSR.hpp
index 979d465aa..3bf8a8881 100644
--- a/Numeric/LFSR.hpp
+++ b/Numeric/LFSR.hpp
@@ -43,7 +43,7 @@ template <typename IntType = uint64_t, IntType polynomial = LSFRPolynomial<IntTy
 		/*!
 			Constructs an LFSR with a random initial value.
 		*/
-		LFSR() {
+		constexpr LFSR() noexcept {
 			// Randomise the value, ensuring it doesn't end up being 0;
 			// don't set any top bits, in case this is a signed type.
 			while(!value_) {
diff --git a/OSBindings/SDL/main.cpp b/OSBindings/SDL/main.cpp
index dd60add58..ccf36a6c4 100644
--- a/OSBindings/SDL/main.cpp
+++ b/OSBindings/SDL/main.cpp
@@ -104,7 +104,7 @@ struct MachineRunner {
 			Stopping,
 			Stopped
 		};
-		std::atomic<State> state_ = State::Running;
+		std::atomic<State> state_{State::Running};
 
 		Time::ScanSynchroniser scan_synchroniser_;
 
diff --git a/Outputs/DisplayMetrics.cpp b/Outputs/DisplayMetrics.cpp
index 3df043af6..8ab24a942 100644
--- a/Outputs/DisplayMetrics.cpp
+++ b/Outputs/DisplayMetrics.cpp
@@ -34,13 +34,13 @@ void Metrics::add_line_total(int total) {
 	line_total_history_pointer_ = (line_total_history_pointer_ + 1) % line_total_history_.size();
 }
 
-float Metrics::visible_lines_per_frame_estimate() {
+float Metrics::visible_lines_per_frame_estimate() const {
 	// Just average the number of records contained in line_total_history_ to provide this estimate;
 	// that array should be an even number, to allow for potential interlaced sources.
 	return float(std::accumulate(line_total_history_.begin(), line_total_history_.end(), 0)) / float(line_total_history_.size());
 }
 
-int Metrics::current_line() {
+int Metrics::current_line() const {
 	return lines_this_frame_;
 }
 
@@ -79,7 +79,7 @@ void Metrics::announce_draw_status(size_t lines, std::chrono::high_resolution_cl
 	}
 }
 
-bool Metrics::should_lower_resolution() {
+bool Metrics::should_lower_resolution() const {
 	// If less than 100 frames are on record, return no opinion; otherwise
 	// suggest a lower resolution if more than 10 frames in the last 100-200
 	// took too long to produce.
diff --git a/Outputs/DisplayMetrics.hpp b/Outputs/DisplayMetrics.hpp
index 4854e950b..9cd4f7889 100644
--- a/Outputs/DisplayMetrics.hpp
+++ b/Outputs/DisplayMetrics.hpp
@@ -29,17 +29,18 @@ class Metrics {
 
 		/// Notifies Metrics that the size of the output buffer has changed.
 		void announce_did_resize();
+
 		/// Provides Metrics with a new data point for output speed estimation.
 		void announce_draw_status(size_t lines, std::chrono::high_resolution_clock::duration duration, bool complete);
 
 		/// @returns @c true if Metrics thinks a lower output buffer resolution is desirable in the abstract; @c false otherwise.
-		bool should_lower_resolution();
+		bool should_lower_resolution() const;
 
 		/// @returns An estimate of the number of lines being produced per frame, excluding vertical sync.
-		float visible_lines_per_frame_estimate();
+		float visible_lines_per_frame_estimate() const;
 
 		/// @returns The number of lines since vertical retrace ended.
-		int current_line();
+		int current_line() const;
 
 	private:
 		int lines_this_frame_ = 0;
diff --git a/Outputs/ScanTarget.hpp b/Outputs/ScanTarget.hpp
index 94529142b..1b25c4bb1 100644
--- a/Outputs/ScanTarget.hpp
+++ b/Outputs/ScanTarget.hpp
@@ -31,8 +31,8 @@ struct Rect {
 		float width, height;
 	} size;
 
-	Rect() : origin({0.0f, 0.0f}), size({1.0f, 1.0f}) {}
-	Rect(float x, float y, float width, float height) :
+	constexpr Rect() : origin({0.0f, 0.0f}), size({1.0f, 1.0f}) {}
+	constexpr Rect(float x, float y, float width, float height) :
 		origin({x, y}), size({width, height}) {}
 };
 
diff --git a/Outputs/Speaker/Speaker.hpp b/Outputs/Speaker/Speaker.hpp
index 13a67e674..0de8f4bc2 100644
--- a/Outputs/Speaker/Speaker.hpp
+++ b/Outputs/Speaker/Speaker.hpp
@@ -118,7 +118,7 @@ class Speaker {
 			}
 			delegate->speaker_did_complete_samples(this, mix_buffer_);
 		}
-		std::atomic<Delegate *> delegate_ = nullptr;
+		std::atomic<Delegate *> delegate_{nullptr};
 
 	private:
 		void compute_output_rate() {
@@ -131,7 +131,7 @@ class Speaker {
 		float input_rate_multiplier_ = 1.0f;
 		float output_cycles_per_second_ = 1.0f;
 		int output_buffer_size_ = 1;
-		std::atomic<bool> stereo_output_ = false;
+		std::atomic<bool> stereo_output_{false};
 		std::vector<int16_t> mix_buffer_;
 };
 
diff --git a/Processors/Z80/Implementation/Z80Base.cpp b/Processors/Z80/Implementation/Z80Base.cpp
index e01bd484b..038daabaf 100644
--- a/Processors/Z80/Implementation/Z80Base.cpp
+++ b/Processors/Z80/Implementation/Z80Base.cpp
@@ -15,7 +15,7 @@ void ProcessorBase::reset_power_on() {
 	last_request_status_ &= ~Interrupt::PowerOn;
 }
 
-uint16_t ProcessorBase::get_value_of_register(Register r) {
+uint16_t ProcessorBase::get_value_of_register(Register r) const {
 	switch (r) {
 		case Register::ProgramCounter:			return pc_.full;
 		case Register::StackPointer:			return sp_.full;
diff --git a/Processors/Z80/Implementation/Z80Implementation.hpp b/Processors/Z80/Implementation/Z80Implementation.hpp
index c328075f0..2685e907e 100644
--- a/Processors/Z80/Implementation/Z80Implementation.hpp
+++ b/Processors/Z80/Implementation/Z80Implementation.hpp
@@ -907,7 +907,7 @@ template <	class T,
 template <	class T,
 			bool uses_bus_request,
 			bool uses_wait_line> bool Processor <T, uses_bus_request, uses_wait_line>
-				::get_bus_request_line() {
+				::get_bus_request_line() const {
 	return bus_request_line_;
 }
 
@@ -922,7 +922,7 @@ template <	class T,
 template <	class T,
 			bool uses_bus_request,
 			bool uses_wait_line> bool Processor <T, uses_bus_request, uses_wait_line>
-				::get_wait_line() {
+				::get_wait_line() const {
 	return wait_line_;
 }
 
@@ -1013,7 +1013,7 @@ template <	class T,
 
 #undef isTerminal
 
-bool ProcessorBase::get_halt_line() {
+bool ProcessorBase::get_halt_line() const {
 	return halt_mask_ == 0x00;
 }
 
@@ -1036,7 +1036,7 @@ void ProcessorBase::set_interrupt_line(bool value, HalfCycles offset) {
 	}
 }
 
-bool ProcessorBase::get_interrupt_line() {
+bool ProcessorBase::get_interrupt_line() const {
 	return irq_line_;
 }
 
@@ -1065,7 +1065,7 @@ void ProcessorBase::set_non_maskable_interrupt_line(bool value, HalfCycles offse
 	}
 }
 
-bool ProcessorBase::get_non_maskable_interrupt_line() {
+bool ProcessorBase::get_non_maskable_interrupt_line() const {
 	return nmi_line_;
 }
 
diff --git a/Processors/Z80/Implementation/Z80Storage.cpp b/Processors/Z80/Implementation/Z80Storage.cpp
index 14bb76de8..b41d8715e 100644
--- a/Processors/Z80/Implementation/Z80Storage.cpp
+++ b/Processors/Z80/Implementation/Z80Storage.cpp
@@ -545,12 +545,12 @@ void ProcessorStorage::assemble_fetch_decode_execute(InstructionPage &target, in
 	target.fetch_decode_execute_data = target.fetch_decode_execute.data();
 }
 
-bool ProcessorBase::is_starting_new_instruction() {
+bool ProcessorBase::is_starting_new_instruction() const {
 	return
 		current_instruction_page_ == &base_page_ &&
 		scheduled_program_counter_ == &base_page_.fetch_decode_execute[0];
 }
 
-bool ProcessorBase::get_is_resetting() {
+bool ProcessorBase::get_is_resetting() const {
 	return request_status_ & (Interrupt::PowerOn | Interrupt::Reset);
 }
diff --git a/Processors/Z80/Z80.hpp b/Processors/Z80/Z80.hpp
index 718ebea27..f470a6614 100644
--- a/Processors/Z80/Z80.hpp
+++ b/Processors/Z80/Z80.hpp
@@ -171,7 +171,7 @@ class ProcessorBase: public ProcessorStorage {
 			@param r The register to set.
 			@returns The value of the register. 8-bit registers will be returned as unsigned.
 		*/
-		uint16_t get_value_of_register(Register r);
+		uint16_t get_value_of_register(Register r) const;
 
 		/*!
 			Sets the value of a register.
@@ -186,7 +186,7 @@ class ProcessorBase: public ProcessorStorage {
 		/*!
 			Gets the value of the HALT output line.
 		*/
-		inline bool get_halt_line();
+		inline bool get_halt_line() const;
 
 		/*!
 			Sets the logical value of the interrupt line.
@@ -200,7 +200,7 @@ class ProcessorBase: public ProcessorStorage {
 		/*!
 			Gets the value of the interrupt line.
 		*/
-		inline bool get_interrupt_line();
+		inline bool get_interrupt_line() const;
 
 		/*!
 			Sets the logical value of the non-maskable interrupt line.
@@ -212,7 +212,7 @@ class ProcessorBase: public ProcessorStorage {
 		/*!
 			Gets the value of the non-maskable interrupt line.
 		*/
-		inline bool get_non_maskable_interrupt_line();
+		inline bool get_non_maskable_interrupt_line() const;
 
 		/*!
 			Sets the logical value of the reset line.
@@ -224,7 +224,7 @@ class ProcessorBase: public ProcessorStorage {
 
 			@returns @c true if the line is logically active; @c false otherwise.
 		*/
-		bool get_is_resetting();
+		bool get_is_resetting() const;
 
 		/*!
 			This emulation automatically sets itself up in power-on state at creation, which has the effect of triggering a
@@ -237,7 +237,7 @@ class ProcessorBase: public ProcessorStorage {
 
 			This is not a speedy operation.
 		*/
-		bool is_starting_new_instruction();
+		bool is_starting_new_instruction() const;
 };
 
 /*!
@@ -271,7 +271,7 @@ template <class T, bool uses_bus_request, bool uses_wait_line> class Processor:
 		/*!
 			Gets the logical value of the bus request line.
 		*/
-		bool get_bus_request_line();
+		bool get_bus_request_line() const;
 
 		/*!
 			Sets the logical value of the wait line, having asserted that this Z80 supports the wait line.
@@ -281,7 +281,7 @@ template <class T, bool uses_bus_request, bool uses_wait_line> class Processor:
 		/*!
 			Gets the logical value of the bus request line.
 		*/
-		bool get_wait_line();
+		bool get_wait_line() const;
 
 	private:
 		T &bus_handler_;
diff --git a/Storage/Disk/Track/Track.hpp b/Storage/Disk/Track/Track.hpp
index d86af916f..7debed708 100644
--- a/Storage/Disk/Track/Track.hpp
+++ b/Storage/Disk/Track/Track.hpp
@@ -84,7 +84,7 @@ class Track {
 				int rhs_largest_position = rhs.position.as_largest();
 				return std::tie(head, largest_position) < std::tie(rhs.head, rhs_largest_position);
 			}
-			Address(int head, HeadPosition position) : head(head), position(position) {}
+			constexpr Address(int head, HeadPosition position) : head(head), position(position) {}
 		};
 
 		/*!
diff --git a/Storage/Storage.hpp b/Storage/Storage.hpp
index f73a52f89..f096e63bb 100644
--- a/Storage/Storage.hpp
+++ b/Storage/Storage.hpp
@@ -22,11 +22,11 @@ namespace Storage {
 */
 struct Time {
 	unsigned int length, clock_rate;
-	Time() : length(0), clock_rate(1) {}
-	Time(unsigned int unsigned_int_value) : length(unsigned_int_value), clock_rate(1) {}
-	Time(int int_value) : Time(unsigned(int_value)) {}
-	Time(unsigned int length, unsigned int clock_rate) : length(length), clock_rate(clock_rate) {}
-	Time(int length, int clock_rate) : Time(unsigned(length), unsigned(clock_rate)) {}
+	constexpr Time() : length(0), clock_rate(1) {}
+	constexpr Time(unsigned int unsigned_int_value) : length(unsigned_int_value), clock_rate(1) {}
+	constexpr Time(int int_value) : Time(unsigned(int_value)) {}
+	constexpr Time(unsigned int length, unsigned int clock_rate) : length(length), clock_rate(clock_rate) {}
+	constexpr Time(int length, int clock_rate) : Time(unsigned(length), unsigned(clock_rate)) {}
 	Time(uint64_t length, uint64_t clock_rate) {
 		install_result(length, clock_rate);
 	}