diff --git a/src/emucore/Props.cxx b/src/emucore/Props.cxx
index 3b168f95a..b97292219 100644
--- a/src/emucore/Props.cxx
+++ b/src/emucore/Props.cxx
@@ -321,7 +321,7 @@ const char* Properties::ourDefaultProperties[LastPropType] = {
   "NO",        // Controller.SwapPaddles
   "AUTO",      // Controller.MouseAxis
   "AUTO",      // Display.Format
-  "34",        // Display.YStart
+  "0",         // Display.YStart
   "210",       // Display.Height
   "NO",        // Display.Phosphor
   "77"         // Display.PPBlend
diff --git a/src/emucore/tia/FrameManager.cxx b/src/emucore/tia/FrameManager.cxx
index ef9649aac..5af3a82ab 100644
--- a/src/emucore/tia/FrameManager.cxx
+++ b/src/emucore/tia/FrameManager.cxx
@@ -44,7 +44,8 @@ static constexpr uInt32
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 FrameManager::FrameManager()
-  : myMode(TvMode::pal)
+  : myMode(TvMode::pal),
+    myYstart(0)
 {
   setTvMode(TvMode::ntsc);
   reset();
@@ -73,11 +74,12 @@ void FrameManager::reset()
   myTotalFrames = 0;
   myFramesInMode = 0;
   myModeConfirmed = false;
-  myVblankMode = VblankMode::floating;
   myLastVblankLines = 0;
   myVblankViolations = 0;
   myStableVblankFrames = 0;
   myVblankViolated = false;
+
+  if (myVblankMode == VblankMode::locked) myVblankMode = VblankMode::floating;
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -153,9 +155,28 @@ void FrameManager::nextLineInVsync()
         myVblankMode = VblankMode::floating;
 
       break;
+
+    case VblankMode::fixed:
+      if (myLineInState > myYstart) setState(State::frame);
+      break;
   }
 }
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+void FrameManager::setYstart(uInt32 ystart)
+{
+  if (ystart == myYstart) return;
+
+  myYstart = ystart;
+
+  myVblankMode = ystart ? VblankMode::fixed : VblankMode::floating;
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+uInt32 FrameManager::ystart() const {
+  return myYstart;
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void FrameManager::setVblank(bool vblank)
 {
diff --git a/src/emucore/tia/FrameManager.hxx b/src/emucore/tia/FrameManager.hxx
index c534aca84..f71bfbb7d 100644
--- a/src/emucore/tia/FrameManager.hxx
+++ b/src/emucore/tia/FrameManager.hxx
@@ -65,6 +65,10 @@ class FrameManager : public Serializable
 
     float frameRate() const { return myFrameRate; }
 
+    void setYstart(uInt32 ystart);
+
+    uInt32 ystart() const;
+
     /**
       Serializable methods (see that class for more information).
     */
@@ -87,7 +91,8 @@ class FrameManager : public Serializable
 
     enum VblankMode {
       locked,
-      floating
+      floating,
+      fixed
     };
 
   private:
@@ -127,6 +132,7 @@ class FrameManager : public Serializable
 
     VblankMode myVblankMode;
     uInt32 myLastVblankLines;
+    uInt32 myYstart;
     uInt8 myVblankViolations;
     uInt8 myStableVblankFrames;
     bool myVblankViolated;
diff --git a/src/emucore/tia/TIA.cxx b/src/emucore/tia/TIA.cxx
index 2e0a297fc..534fd72d6 100644
--- a/src/emucore/tia/TIA.cxx
+++ b/src/emucore/tia/TIA.cxx
@@ -619,7 +619,7 @@ uInt32 TIA::height() const
 // TODO: stub
 uInt32 TIA::ystart() const
 {
-  return 0;
+  return myFrameManager.ystart();
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -632,6 +632,7 @@ void TIA::setHeight(uInt32 height)
 // TODO: stub
 void TIA::setYStart(uInt32 ystart)
 {
+  myFrameManager.setYstart(ystart);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -