diff --git a/Components/5380/DirectAccessDevice.cpp b/Components/5380/DirectAccessDevice.cpp
index 6d776836e..d09f64fec 100644
--- a/Components/5380/DirectAccessDevice.cpp
+++ b/Components/5380/DirectAccessDevice.cpp
@@ -25,26 +25,30 @@ void DirectAccessDevice::scsi_bus_did_change(Bus *, BusState new_state) {
 		time."
 	*/
 
-	switch(state_) {
-		case State::Inactive:
+	switch(phase_) {
+		case Phase::AwaitingSelection:
 			if(
 				(new_state & scsi_id_mask_) &&
 				((new_state & (Line::SelectTarget | Line::Busy | Line::Input)) == Line::SelectTarget)
 			) {
-				state_ = State::Selected;
-				bus_state_ |= Line::Busy | Line::Request;
+				phase_ = Phase::Command;
+				bus_state_ |= Line::Busy | Line::Request | Line::Control;	// Initiate the command phase: request a command byte.
 				bus_.set_device_output(scsi_bus_device_id_, bus_state_);
 			}
 		break;
 
-		case State::Selected:
+		case Phase::Command:
 			switch(new_state & (Line::Request | Line::Acknowledge)) {
+				// If request and acknowledge are both enabled, grab a byte and cancel the request.
 				case Line::Request | Line::Acknowledge:
 					bus_state_ &= ~Line::Request;
 					printf("Got %02x maybe?\n", bus_state_ & 0xff);
+
+					// TODO: is the command phase over?
 				break;
 
-				case Line::Acknowledge:
+				// The reset of request has caused the initiator to reset acknowledge, so it is now
+				// safe to request the next byte.
 				case 0:
 					bus_state_ |= Line::Request;
 				break;
diff --git a/Components/5380/DirectAccessDevice.hpp b/Components/5380/DirectAccessDevice.hpp
index e92d486ce..9ff616f56 100644
--- a/Components/5380/DirectAccessDevice.hpp
+++ b/Components/5380/DirectAccessDevice.hpp
@@ -32,10 +32,10 @@ class DirectAccessDevice: public Bus::Observer {
 		const BusState scsi_id_mask_;
 		const size_t scsi_bus_device_id_;
 
-		enum class State {
-			Inactive,
-			Selected
-		} state_ = State::Inactive;
+		enum class Phase {
+			AwaitingSelection,
+			Command
+		} phase_ = Phase::AwaitingSelection;
 		BusState bus_state_ = DefaultBusState;
 };