diff --git a/Components/9918/Implementation/9918.cpp b/Components/9918/Implementation/9918.cpp
index 5adb22a24..09d475f84 100644
--- a/Components/9918/Implementation/9918.cpp
+++ b/Components/9918/Implementation/9918.cpp
@@ -890,6 +890,32 @@ void Base<personality>::commit_register(int reg, uint8_t value) {
 				LOG("TODO: Yamaha command; " << PADHEX(2) << +value);
 				// b0–b3: LO0–LO3 (???)
 				// b4–b7: CM0-CM3 (???)
+
+				switch(value >> 4) {
+					// All codes not listed below are invalid; just abandon
+					// whatever's going on, if anything.
+					default:		Storage<personality>::command_ = nullptr;
+
+					case 0b0000:	break;	// TODO: stop.
+					case 0b0100:	break;	// TODO: point.
+					case 0b0101:	break;	// TODO: pset.
+					case 0b0110:	break;	// TODO: srch.
+					case 0b0111:
+						Storage<personality>::command_ = std::make_unique<Commands::Line>(Storage<personality>::command_context_);
+					break;
+
+					case 0b1000:	break;	// TODO: lmmv.
+					case 0b1001:	break;	// TODO: lmmm.
+					case 0b1010:	break;	// TODO: lmcm.
+					case 0b1011:	break;	// TODO: lmmc.
+
+					case 0b1100:	break;	// TODO: hmmv.
+					case 0b1101:	break;	// TODO: hmmm.
+					case 0b1110:	break;	// TODO: ymmm.
+					case 0b1111:	break;	// TODO: hmmc.
+				}
+
+				// TODO: record logical mode.
 			break;
 		}
 	}
diff --git a/Components/9918/Implementation/9918Base.hpp b/Components/9918/Implementation/9918Base.hpp
index b5b797501..2516a08be 100644
--- a/Components/9918/Implementation/9918Base.hpp
+++ b/Components/9918/Implementation/9918Base.hpp
@@ -183,7 +183,7 @@ template <Personality personality> struct Storage<personality, std::enable_if_t<
 
 	// Command engine state.
 	CommandContext command_context_;
-	Command *command_ = nullptr;
+	std::unique_ptr<Command> command_ = nullptr;
 
 	Storage() noexcept {
 		// Perform sanity checks on the event lists.
diff --git a/Components/9918/Implementation/YamahaCommands.hpp b/Components/9918/Implementation/YamahaCommands.hpp
index 692c411c0..2b469f878 100644
--- a/Components/9918/Implementation/YamahaCommands.hpp
+++ b/Components/9918/Implementation/YamahaCommands.hpp
@@ -14,6 +14,8 @@
 namespace TI {
 namespace TMS {
 
+// MARK: - Generics.
+
 struct CommandContext {
 	int source_x = 0, source_y = 0;
 	int destination_x = 0, destination_y = 0;
@@ -32,14 +34,32 @@ struct Command {
 	int cycles = 0;
 	uint8_t value = 0;
 
+	// TODO: how best to describe access destination? Probably as (x, y) and logical/fast?
+
 	/// Current command parameters.
 	CommandContext &context;
 	Command(CommandContext &context) : context(context) {}
 
-	/// Request that the fields above are updated given the completed access.
+	/// Request that the fields above are updated given that the previously-request access
+	/// was completed.
+	///
+	/// @returns @c true if another access has been enqueued; @c false if this command is done.
 	virtual bool next() = 0;
 };
 
+// MARK: - Line drawing.
+
+namespace Commands {
+
+struct Line: public Command {
+	using Command::Command;
+
+	bool next() {
+		return false;
+	}
+};
+
+}
 }
 }