diff --git a/Virtu/GamePort.cs b/Virtu/GamePort.cs
index 7d70bbe..ff56aea 100644
--- a/Virtu/GamePort.cs
+++ b/Virtu/GamePort.cs
@@ -42,7 +42,7 @@ public bool ReadButton2()
         {
             var settings = Machine.Settings.GamePort;
 
-            return (_gamePortService.IsButton2Down || _keyboardService.IsShiftKeyDown || // [TN9]
+            return (_gamePortService.IsButton2Down || !_keyboardService.IsShiftKeyDown || // Shift' [TN9]
                 (settings.UseKeyboard && (settings.Key.Button2 > 0) && _keyboardService.IsKeyDown(settings.Key.Button2)));
         }
 
diff --git a/Virtu/Memory.cs b/Virtu/Memory.cs
index 0a486c7..9e78321 100644
--- a/Virtu/Memory.cs
+++ b/Virtu/Memory.cs
@@ -351,7 +351,7 @@ private int ReadIoRegionC1C7(int address)
 
         private int ReadIoRegionC3C3(int address)
         {
-            _slotRegionC8CF = (address >> 8) & 0x07;
+            _slotRegionC8CF = 3;
             if (!IsRomC3C3External)
             {
                 SetRomC8CF(true); // $C3XX sets IntC8Rom; inhibits I/O Strobe' [5-28, 7-21]
@@ -543,7 +543,7 @@ private void WriteIoRegionC1C7(int address, byte data)
 
         private void WriteIoRegionC3C3(int address, byte data)
         {
-            _slotRegionC8CF = (address >> 8) & 0x07;
+            _slotRegionC8CF = 3;
             if (!IsRomC3C3External)
             {
                 SetRomC8CF(true); // $C3XX sets IntC8Rom; inhibits I/O Strobe' [5-28, 7-21]