diff --git a/Changes.txt b/Changes.txt
index 0974a3d6e..40b0374a7 100644
--- a/Changes.txt
+++ b/Changes.txt
@@ -70,7 +70,8 @@
 
   * Fixed bug in debugger tracing and displaying the partial TIA image;
     the first time entering the debugger and starting to trace, the image
-    was blanked out (black) instead of being drawn in greyscale.
+    was blanked out (black) instead of being drawn in greyscale.  Also, the
+    image is now synchronized, instead of being two frames behind.
 
   * Fixed crash with zipped ROMs that are less than 4K in size; so far
     this bug has only ever occurred in Windows XP, but it's been there
@@ -124,7 +125,8 @@
     This fixes issues with a newer ZLIB not working with an older PNG, etc.
 
   * Updated build scripts for Visual Studio 2017 (Windows) and MacOS
-    Sierra (latest version of Xcode).
+    Sierra (latest version of Xcode), and make these the minimum supported
+    versions.
 
   * Updated UNIX configure script to work with the clang 5+ and gcc 7+
     compiler versions, and fixed compile issues on AArch64 and ppc64le
diff --git a/src/debugger/gui/TiaOutputWidget.cxx b/src/debugger/gui/TiaOutputWidget.cxx
index 70168058d..5ccbbd8e5 100644
--- a/src/debugger/gui/TiaOutputWidget.cxx
+++ b/src/debugger/gui/TiaOutputWidget.cxx
@@ -169,7 +169,5 @@ void TiaOutputWidget::drawWidget(bool hilite)
 
   // Show electron beam position
   if(visible && scanx < width && scany+2u < height)
-  {
     s.fillRect(_x+(scanx<<1), _y+scany, 3, 3, kBtnTextColor);
-  }
 }
diff --git a/src/debugger/gui/TiaZoomWidget.cxx b/src/debugger/gui/TiaZoomWidget.cxx
index 1656c6254..b65adef89 100644
--- a/src/debugger/gui/TiaZoomWidget.cxx
+++ b/src/debugger/gui/TiaZoomWidget.cxx
@@ -246,7 +246,7 @@ void TiaZoomWidget::drawWidget(bool hilite)
   // Draw the zoomed image
   // This probably isn't as efficient as it can be, but it's a small area
   // and I don't have time to make it faster :)
-  const uInt8* currentFrame  = instance().console().tia().currentFrameBuffer();
+  const uInt8* currentFrame  = instance().console().tia().frameBuffer();
   const int width = instance().console().tia().width(),
             wzoom = myZoomLevel << 1,
             hzoom = myZoomLevel;
diff --git a/src/emucore/TIASurface.cxx b/src/emucore/TIASurface.cxx
index eca183eec..2ad1effca 100644
--- a/src/emucore/TIASurface.cxx
+++ b/src/emucore/TIASurface.cxx
@@ -121,7 +121,7 @@ void TIASurface::setPalette(const uInt32* tia_palette, const uInt32* rgb_palette
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-const FBSurface& TIASurface::baseSurface(GUI::Rect& rect)
+const FBSurface& TIASurface::baseSurface(GUI::Rect& rect) const
 {
   uInt32 tiaw = myTIA->width(), width = tiaw*2, height = myTIA->height();
   rect.setBounds(0, 0, width, height);
@@ -146,10 +146,8 @@ const FBSurface& TIASurface::baseSurface(GUI::Rect& rect)
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 uInt32 TIASurface::pixel(uInt32 idx, uInt8 shift) const
 {
-  uInt8 c = *(myTIA->currentFrameBuffer() + idx) | shift;
-  uInt8 p = *(myTIA->previousFrameBuffer() + idx) | shift;
-
-  return (!myUsePhosphor ? myPalette[c] : myPhosphorPalette[c][p]);
+// FIXME - use TJ phosphor code
+  return myPalette[*(myTIA->frameBuffer() + idx) | shift];
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -303,10 +301,9 @@ void TIASurface::render()
   // In hardware rendering mode, it's faster to just assume that the screen
   // is dirty and always do an update
 
-  uInt8* currentFrame  = myTIA->currentFrameBuffer();
-  uInt8* previousFrame = myTIA->previousFrameBuffer();
-  uInt32 width         = myTIA->width();
-  uInt32 height        = myTIA->height();
+  uInt8* fbuffer = myTIA->frameBuffer();
+  uInt32 width   = myTIA->width();
+  uInt32 height  = myTIA->height();
 
   uInt32 *buffer, pitch;
   myTiaSurface->basePtr(buffer, pitch);
@@ -323,7 +320,7 @@ void TIASurface::render()
       {
         uInt32 pos = screenofsY;
         for(uInt32 x = 0; x < width; ++x)
-          buffer[pos++] = myPalette[currentFrame[bufofsY + x]];
+          buffer[pos++] = myPalette[fbuffer[bufofsY + x]];
 
         bufofsY    += width;
         screenofsY += pitch;
@@ -332,6 +329,7 @@ void TIASurface::render()
     }
     case kPhosphor:
     {
+#if 0 // FIXME
       uInt32 bufofsY    = 0;
       uInt32 screenofsY = 0;
       for(uInt32 y = 0; y < height; ++y)
@@ -345,18 +343,20 @@ void TIASurface::render()
         bufofsY    += width;
         screenofsY += pitch;
       }
+#endif
       break;
     }
     case kBlarggNormal:
     {
-      myNTSCFilter.blit_single(currentFrame, width, height,
-                               buffer, pitch << 2);
+      myNTSCFilter.blit_single(fbuffer, width, height, buffer, pitch << 2);
       break;
     }
     case kBlarggPhosphor:
     {
+#if 0 // FIXME
       myNTSCFilter.blit_double(currentFrame, previousFrame, width, height,
                                buffer, pitch << 2);
+#endif
       break;
     }
   }
diff --git a/src/emucore/TIASurface.hxx b/src/emucore/TIASurface.hxx
index 0c5750253..ce8416971 100644
--- a/src/emucore/TIASurface.hxx
+++ b/src/emucore/TIASurface.hxx
@@ -67,7 +67,7 @@ class TIASurface
     /**
       Get the TIA base surface for use in saving to a PNG image.
     */
-    const FBSurface& baseSurface(GUI::Rect& rect);
+    const FBSurface& baseSurface(GUI::Rect& rect) const;
 
     /**
       Get the TIA pixel associated with the given TIA buffer index,
diff --git a/src/emucore/tia/TIA.cxx b/src/emucore/tia/TIA.cxx
index 9caf8741b..bb7390643 100644
--- a/src/emucore/tia/TIA.cxx
+++ b/src/emucore/tia/TIA.cxx
@@ -85,8 +85,7 @@ TIA::TIA(Console& console, Sound& sound, Settings& settings)
     }
   );
 
-  myCurrentFrameBuffer  = make_ptr<uInt8[]>(160 * FrameManager::frameBufferHeight);
-  myPreviousFrameBuffer = make_ptr<uInt8[]>(160 * FrameManager::frameBufferHeight);
+  myFramebuffer  = make_ptr<uInt8[]>(160 * FrameManager::frameBufferHeight);
 
   myTIAPinsDriven = mySettings.getBool("tiadriven");
 
@@ -152,7 +151,7 @@ void TIA::reset()
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void TIA::frameReset()
 {
-  clearBuffers();
+  memset(myFramebuffer.get(), 0, 160 * FrameManager::frameBufferHeight);
   myAutoFrameEnabled = mySettings.getInt("framerate") <= 0;
   enableColorLoss(mySettings.getBool("colorloss"));
 }
@@ -194,13 +193,6 @@ void TIA::installDelegate(System& system, Device& device)
   );
 }
 
-// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void TIA::clearBuffers()
-{
-  memset(myCurrentFrameBuffer.get(), 0, 160 * FrameManager::frameBufferHeight);
-  memset(myPreviousFrameBuffer.get(), 0, 160 * FrameManager::frameBufferHeight);
-}
-
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool TIA::save(Serializer& out) const
 {
@@ -715,7 +707,7 @@ bool TIA::saveDisplay(Serializer& out) const
 {
   try
   {
-    out.putByteArray(myCurrentFrameBuffer.get(), 160*320);
+    out.putByteArray(myFramebuffer.get(), 160*FrameManager::frameBufferHeight);
   }
   catch(...)
   {
@@ -732,9 +724,7 @@ bool TIA::loadDisplay(Serializer& in)
   try
   {
     // Reset frame buffer pointer and data
-    clearBuffers();
-    in.getByteArray(myCurrentFrameBuffer.get(), 160*320);
-    memcpy(myPreviousFrameBuffer.get(), myCurrentFrameBuffer.get(), 160*320);
+    in.getByteArray(myFramebuffer.get(), 160*FrameManager::frameBufferHeight);
   }
   catch(...)
   {
@@ -991,21 +981,13 @@ void TIA::updateEmulation()
   cycle(cyclesToRun);
 }
 
-// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void TIA::swapBuffers()
-{
-  myCurrentFrameBuffer.swap(myPreviousFrameBuffer);
-}
-
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void TIA::onFrameStart()
 {
-  swapBuffers();
-
   const Int32 x = myHctr - 68;
 
   if (x > 0)
-    memset(myCurrentFrameBuffer.get(), 0, x);
+    memset(myFramebuffer.get(), 0, x);
 
   for (uInt8 i = 0; i < 4; i++)
     updatePaddle(i);
@@ -1039,7 +1021,7 @@ void TIA::onFrameComplete()
   // Blank out any extra lines not drawn this frame
   const uInt32 missingScanlines = myFrameManager.missingScanlines();
   if (missingScanlines > 0)
-    memset(myCurrentFrameBuffer.get() + 160 * myFrameManager.getY(), 0, missingScanlines * 160);
+    memset(myFramebuffer.get() + 160 * myFrameManager.getY(), 0, missingScanlines * 160);
 
   // Recalculate framerate, attempting to auto-correct for scanline 'jumps'
   if(myAutoFrameEnabled)
@@ -1142,7 +1124,7 @@ void TIA::applyRsync()
 
   myXDelta = 157 - x;
   if (myFrameManager.isRendering())
-    memset(myCurrentFrameBuffer.get() + myFrameManager.getY() * 160 + x, 0, 160 - x);
+    memset(myFramebuffer.get() + myFrameManager.getY() * 160 + x, 0, 160 - x);
 
   myHctr = 225;
 }
@@ -1176,7 +1158,7 @@ void TIA::cloneLastLine()
 
   if (!myFrameManager.isRendering() || y == 0) return;
 
-  uInt8* buffer = myCurrentFrameBuffer.get();
+  uInt8* buffer = myFramebuffer.get();
 
   memcpy(buffer + y * 160, buffer + (y-1) * 160, 160);
 }
@@ -1243,7 +1225,7 @@ void TIA::renderPixel(uInt32 x, uInt32 y)
       break;
   }
 
-  myCurrentFrameBuffer.get()[y * 160 + x] = myFrameManager.vblank() ? 0 : color;
+  myFramebuffer.get()[y * 160 + x] = myFrameManager.vblank() ? 0 : color;
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -1269,7 +1251,7 @@ void TIA::flushLineCache()
 void TIA::clearHmoveComb()
 {
   if (myFrameManager.isRendering() && myHstate == HState::blank)
-    memset(myCurrentFrameBuffer.get() + myFrameManager.getY() * 160,
+    memset(myFramebuffer.get() + myFrameManager.getY() * 160,
            myColorHBlank, 8);
 }
 
diff --git a/src/emucore/tia/TIA.hxx b/src/emucore/tia/TIA.hxx
index 18c47e1f2..8c653b43d 100644
--- a/src/emucore/tia/TIA.hxx
+++ b/src/emucore/tia/TIA.hxx
@@ -76,12 +76,12 @@ class TIA : public Device
 
   public:
     /**
-      Reset device to its power-on state
+      Reset device to its power-on state.
     */
     void reset() override;
 
     /**
-      Reset frame to current YStart/Height properties
+      Reset frame to current YStart/Height properties.
     */
     void frameReset();
 
@@ -100,14 +100,14 @@ class TIA : public Device
     void install(System& system) override;
 
     /**
-      Get the byte at the specified address
+      Get the byte at the specified address.
 
       @return The byte at the specified address
     */
     uInt8 peek(uInt16 address) override;
 
     /**
-      Change the byte at the specified address to the given value
+      Change the byte at the specified address to the given value.
 
       @param address  The address where the value should be stored
       @param value    The value to be stored at the address
@@ -157,13 +157,12 @@ class TIA : public Device
     void update();
 
     /**
-      Answers the current and previous frame buffer pointers
+      Returns pointer to the internal frame buffer.
     */
-    uInt8* currentFrameBuffer() const  { return myCurrentFrameBuffer.get();  }
-    uInt8* previousFrameBuffer() const { return myPreviousFrameBuffer.get(); }
+    uInt8* frameBuffer() const { return myFramebuffer.get();  }
 
     /**
-      Answers dimensional info about the framebuffer
+      Answers dimensional info about the framebuffer.
     */
     uInt32 width() const  { return 160; }
     uInt32 height() const { return myFrameManager.height(); }
@@ -305,9 +304,6 @@ class TIA : public Device
     bool toggleJitter(uInt8 mode = 2);
     void setJitterRecoveryFactor(Int32 factor) { myFrameManager.setJitterFactor(factor); }
 
-    // Clear both internal TIA buffers to black (palette color 0)
-    void clearBuffers();
-
     /**
       This method should be called to update the TIA with a new scanline.
     */
@@ -326,12 +322,12 @@ class TIA : public Device
     TIA& updateScanlineByTrace(int target);
 
     /**
-      Retrieve the last value written to a certain register
+      Retrieve the last value written to a certain register.
     */
     uInt8 registerValue(uInt8 reg) const;
 
     /**
-      Get the current x value
+      Get the current x value.
     */
     uInt8 getPosition() const {
       return (myHctr < 68) ? 0 : (myHctr - 68 - myXDelta);
@@ -339,7 +335,7 @@ class TIA : public Device
 
     /**
       Flush the line cache after an externally triggered state change
-      (e.g. a register write)
+      (e.g. a register write).
     */
     void flushLineCache();
 
@@ -431,8 +427,6 @@ class TIA : public Device
 
     uInt8 resxCounter();
 
-    void swapBuffers();
-
     /**
       Get the result of the specified collision register.
     */
@@ -469,9 +463,8 @@ class TIA : public Device
     LatchedInput myInput0;
     LatchedInput myInput1;
 
-    // Pointer to the current and previous frame buffers
-    BytePtr myCurrentFrameBuffer;
-    BytePtr myPreviousFrameBuffer;
+    // Pointer to the internal frame buffer
+    BytePtr myFramebuffer;
 
     bool myTIAPinsDriven;