diff --git a/Components/9918/Implementation/9918.cpp b/Components/9918/Implementation/9918.cpp
index 5ebe4761b..39c78b843 100644
--- a/Components/9918/Implementation/9918.cpp
+++ b/Components/9918/Implementation/9918.cpp
@@ -265,7 +265,8 @@ void TMS9918<personality>::run_for(const HalfCycles cycles) {
 				this->write_pointer_.row = (this->write_pointer_.row + 1) % this->mode_timing_.total_lines;
 				LineBuffer &next_line_buffer = this->line_buffers_[this->write_pointer_.row];
 
-				// Establish the output mode for the next line.
+				// Establish the current screen output mode, which will be captured as a
+				// line mode momentarily.
 				this->screen_mode_ = this->current_screen_mode();
 
 				// Based on the output mode, pick a line mode.
@@ -274,9 +275,13 @@ void TMS9918<personality>::run_for(const HalfCycles cycles) {
 				this->mode_timing_.maximum_visible_sprites = 4;
 				switch(this->screen_mode_) {
 					case ScreenMode::Text:
-						next_line_buffer.line_mode = LineMode::Text;
-						next_line_buffer.first_pixel_output_column = Timing<personality>::FirstTextCycle;
-						next_line_buffer.next_border_column = Timing<personality>::LastTextCycle;
+						if constexpr (Timing<personality>::SupportsTextMode) {
+							next_line_buffer.line_mode = LineMode::Text;
+							next_line_buffer.first_pixel_output_column = Timing<personality>::FirstTextCycle;
+							next_line_buffer.next_border_column = Timing<personality>::LastTextCycle;
+						} else {
+							next_line_buffer.line_mode = LineMode::Refresh;
+						}
 					break;
 					case ScreenMode::SMSMode4:
 						next_line_buffer.line_mode = LineMode::SMS;
diff --git a/Components/9918/Implementation/ClockConverter.hpp b/Components/9918/Implementation/ClockConverter.hpp
index 8dd6c9c5f..a9d562aca 100644
--- a/Components/9918/Implementation/ClockConverter.hpp
+++ b/Components/9918/Implementation/ClockConverter.hpp
@@ -31,6 +31,10 @@ struct Timing<personality, std::enable_if_t<is_classic_vdp(personality)>> {
 	/// Pixels implicitly run from here to the end of the line.
 	constexpr static int FirstPixelCycle = 86;
 
+	/// Indicates whether text modes are supported by this VDP. If so then
+	/// values for First & Last TextCycle are required. If not then they can be omitted.
+	constexpr static bool SupportsTextMode = true;
+
 	/// The first internal cycle at which pixels will be output text mode.
 	constexpr static int FirstTextCycle = 94;
 
@@ -43,6 +47,7 @@ struct Timing<personality, std::enable_if_t<is_yamaha_vdp(personality)>> {
 	constexpr static int CyclesPerLine = 1368;
 	constexpr static int VRAMAccessDelay = 6;
 	constexpr static int FirstPixelCycle = 344;
+	constexpr static bool SupportsTextMode = true;
 	constexpr static int FirstTextCycle = 376;
 	constexpr static int LastTextCycle = 1336;
 };
@@ -52,8 +57,7 @@ struct Timing<Personality::MDVDP> {
 	constexpr static int CyclesPerLine = 3420;
 	constexpr static int VRAMAccessDelay = 6;
 	constexpr static int FirstPixelCycle = 860;
-	constexpr static int FirstTextCycle = 940;
-	constexpr static int LastTextCycle = 3340;
+	constexpr static bool SupportsTextMode = false;
 };
 
 constexpr int TMSAccessWindowsPerLine = 171;