Add soft reset for the Thomson machines.

Machines/Thomson/MO/MO.cpp

@@ -63,8 +63,9 @@ struct ConcreteMachine:
 	public MachineTypes::MappedKeyboardMachine,
 	public MachineTypes::MediaChangeObserver,
 	public MachineTypes::MediaTarget,
-	public MachineTypes::TimedMachine,
+	public MachineTypes::SoftResettable,
 	public MachineTypes::ScanProducer,
+	public MachineTypes::TimedMachine,
 	public Machine,
 	public Utility::TypeRecipient<Thomson::MO::Keyboard::CharacterMapper>
 {
@@ -620,6 +621,13 @@ private:
 		}
 	}
 
+	// MARK: - Resettable.
+
+	void soft_reset() final {
+		m6809_.template set<CPU::M6809::Line::PowerOnReset>(true);
+		memory_.reset();
+	}
+
 	// MARK: - MappedKeyboardMachine.
 
 	Thomson::MO::Keyboard::KeyboardMapper keyboard_mapper_;

Machines/Thomson/MO/MemoryMap.hpp

@@ -135,6 +135,21 @@ public:
 		Memory::Fuzz(video_);
 	}
 
+	void reset() {
+		page_video(false);
+
+		cartridge_page_ = 0;
+		cartridge_page_ = 0;
+		rom_page_ = 0;
+		ram_page_ = 1;
+		basic_selection_ = false;
+		b000page_ = B000Page::Empty;
+
+		access_mode_ = AccessMode::LightPen;
+		update_commutable_ram();
+		update_commutable_rom();
+	}
+
 	// MARK: - ROM installation and connection for video.
 
 	void set_rom(const std::vector<uint8_t> &rom) {