diff --git a/src/common/AudioSettings.cxx b/src/common/AudioSettings.cxx
index 640ba9527..6f67d3d0a 100644
--- a/src/common/AudioSettings.cxx
+++ b/src/common/AudioSettings.cxx
@@ -43,8 +43,7 @@ namespace {
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 AudioSettings::AudioSettings(Settings& settings)
-  : mySettings(settings),
-    myIsPersistent(true)
+  : mySettings(settings)
 {
   setPreset(normalizedPreset(mySettings.getInt(SETTING_PRESET)));
 }
diff --git a/src/common/AudioSettings.hxx b/src/common/AudioSettings.hxx
index d319671c3..1e9f0477f 100644
--- a/src/common/AudioSettings.hxx
+++ b/src/common/AudioSettings.hxx
@@ -131,13 +131,13 @@ class AudioSettings
 
     Preset myPreset;
 
-    uInt32 myPresetSampleRate;
-    uInt32 myPresetFragmentSize;
-    uInt32 myPresetBufferSize;
-    uInt32 myPresetHeadroom;
+    uInt32 myPresetSampleRate{0};
+    uInt32 myPresetFragmentSize{0};
+    uInt32 myPresetBufferSize{0};
+    uInt32 myPresetHeadroom{0};
     ResamplingQuality myPresetResamplingQuality;
 
-    bool myIsPersistent;
+    bool myIsPersistent{true};
 };
 
 #endif // AUDIO_PARAMTERS_HXX
diff --git a/src/common/FpsMeter.cxx b/src/common/FpsMeter.cxx
index be945e9e2..878a42ae0 100644
--- a/src/common/FpsMeter.cxx
+++ b/src/common/FpsMeter.cxx
@@ -19,12 +19,14 @@
 
 using namespace std::chrono;
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 FpsMeter::FpsMeter(uInt32 queueSize)
   : myQueue(queueSize)
 {
   reset();
 }
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void FpsMeter::reset(uInt32 garbageFrameLimit)
 {
   myQueue.clear();
@@ -35,6 +37,7 @@ void FpsMeter::reset(uInt32 garbageFrameLimit)
   myGarbageFrameLimit = garbageFrameLimit;
 }
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void FpsMeter::render(uInt32 frameCount)
 {
   if (myGarbageFrameCounter < myGarbageFrameLimit) {
@@ -67,6 +70,7 @@ void FpsMeter::render(uInt32 frameCount)
   if (myTimeInterval > 0) myFps = (myFrameCount - first.frames) / myTimeInterval;
 }
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 float FpsMeter::fps() const
 {
   return myFps;
diff --git a/src/common/HighScoresManager.cxx b/src/common/HighScoresManager.cxx
index 245b4e38c..9411d0a7a 100644
--- a/src/common/HighScoresManager.cxx
+++ b/src/common/HighScoresManager.cxx
@@ -48,7 +48,6 @@
 #include "Cart.hxx"
 #include "Console.hxx"
 #include "Launcher.hxx"
-#include "json.hxx"
 #include "Base.hxx"
 
 #include "HighScoresManager.hxx"
@@ -57,7 +56,6 @@ using namespace BSPF;
 using namespace std;
 using namespace HSM;
 using Common::Base;
-using json = nlohmann::json;
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 HighScoresManager::HighScoresManager(OSystem& osystem)
@@ -79,10 +77,23 @@ Int16 HighScoresManager::peek(uInt16 addr) const
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-Properties& HighScoresManager::properties(Properties& props) const
+const json HighScoresManager::properties(const Properties& props) const
 {
+  const string& property = props.get(PropType::Cart_Highscore);
 
-  if (myOSystem.hasConsole())
+  if(property.empty())
+    return json::array();
+
+  return json::parse(property);
+}
+
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+json HighScoresManager::properties(json& jprops) const
+{
+  Properties props;
+
+  if(myOSystem.hasConsole())
   {
     props = myOSystem.console().properties();
   }
@@ -91,323 +102,208 @@ Properties& HighScoresManager::properties(Properties& props) const
     const string& md5 = myOSystem.launcher().selectedRomMD5();
     myOSystem.propSet().getMD5(md5, props);
   }
-  return props;
+
+  return jprops = properties(props);
 }
 
-//// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-//string HighScoresManager::getPropIdx(const Properties& props, PropType type, uInt32 idx) const
-//{
-//  string property = props.get(type);
-//
-//  replace(property.begin(), property.end(), ',', ' ');
-//  replace(property.begin(), property.end(), '|', ' ');
-//  istringstream buf(property);
-//  string result;
-//
-//  for (uInt32 i = 0; i <= idx; ++i)
-//    if(!(buf >> result))
-//      return "";
-//
-//  return result;
-//}
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool HighScoresManager::enabled() const
 {
-  Properties props;
+  json hsProp;
 
-  return !getPropStr(properties(props), SCORE_ADDRESS_0).empty();
-
-  //return (!getPropIdx(properties(props), PropType::Cart_Addresses, 0).empty());
+  return properties(hsProp).contains(SCORE_ADDRESSES);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-uInt32 HighScoresManager::numVariations(const Properties& props) const
+uInt32 HighScoresManager::numVariations(const json& jprops) const
 {
-  return min(getPropInt(props, VARIATIONS_COUNT, DEFAULT_VARIATION), MAX_VARIATIONS);
-
-  //string numVariations = getPropIdx(props, PropType::Cart_Variations);
-  //uInt32 maxVariations = MAX_VARIATIONS;
-
-  //return min(uInt32(stringToInt(numVariations, DEFAULT_VARIATION)), maxVariations);
+  return min(getPropInt(jprops, VARIATIONS_COUNT, DEFAULT_VARIATION), MAX_VARIATIONS);
 }
 
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool HighScoresManager::get(const Properties& props, uInt32& numVariationsR,
                             ScoresInfo& info) const
 {
-  numVariationsR = numVariations(props);
+  json jprops = properties(props);
 
-  //info.armRAM = armRAM(props);
-  info.numDigits = numDigits(props);
-  info.trailingZeroes = trailingZeroes(props);
-  info.scoreBCD = scoreBCD(props);
-  info.scoreInvert = scoreInvert(props);
-  info.varsBCD = varBCD(props);
-  info.varsZeroBased = varZeroBased(props);
-  info.special = specialLabel(props);
-  info.specialBCD = specialBCD(props);
-  info.specialZeroBased = specialZeroBased(props);
-  info.notes = notes(props);
+  numVariationsR = numVariations(jprops);
 
-  info.varsAddr = varAddress(props);
-  info.specialAddr = specialAddress(props);
+  //info.armRAM = armRAM(jprops);
+  info.numDigits = numDigits(jprops);
+  info.trailingZeroes = trailingZeroes(jprops);
+  info.scoreBCD = scoreBCD(jprops);
+  info.scoreInvert = scoreInvert(jprops);
+  info.varsBCD = varBCD(jprops);
+  info.varsZeroBased = varZeroBased(jprops);
+  info.special = specialLabel(jprops);
+  info.specialBCD = specialBCD(jprops);
+  info.specialZeroBased = specialZeroBased(jprops);
+  info.notes = notes(jprops);
 
-  int num = numAddrBytes(props);
-  if(num >= 1)
-    info.scoreAddr[0] = getPropAddr(props, SCORE_ADDRESS_0);
-  if(num >= 2)
-    info.scoreAddr[1] = getPropAddr(props, SCORE_ADDRESS_1);
-  if(num >= 3)
-    info.scoreAddr[2] = getPropAddr(props, SCORE_ADDRESS_2);
-  if(num >= 4)
-    info.scoreAddr[3] = getPropAddr(props, SCORE_ADDRESS_3);
+  info.varsAddr = varAddress(jprops);
+  info.specialAddr = specialAddress(jprops);
 
-  return !getPropStr(props, SCORE_ADDRESS_0).empty();
+  info.scoreAddr = getPropScoreAddr(jprops);
 
-  //for (uInt32 a = 0; a < numAddrBytes(props); ++a)
+  //if(jprops.contains(SCORE_ADDRESSES))
   //{
+  //  const json addrProps = jprops.at(SCORE_ADDRESSES);
 
+  //  if(!addrProps.empty() && addrProps.is_array())
+  //  {
+  //    int a = 0;
 
+  //    for(const json& addresses : addrProps)
+  //    {
+  //      const string address = addresses.get<string>();
 
-  //  string addr = getPropIdx(props, PropType::Cart_Addresses, a);
+  //      if(address.empty())
+  //        info.scoreAddr[a++] = DEFAULT_ADDRESS;
+  //      else
+  //        info.scoreAddr[a++] = fromHexStr(address);
+  //    }
 
-  //  info.scoreAddr[a] = stringToIntBase16(addr);
+  //  }
   //}
 
-  //return (!getPropIdx(props, PropType::Cart_Addresses, 0).empty());
+  return enabled();
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void HighScoresManager::set(Properties& props, uInt32 numVariations,
                             const ScoresInfo& info) const
 {
-  uInt32 maxVariations = MAX_VARIATIONS;
-  json hsProp = json::object();
+  json jprops = json::object();
 
   // handle variations
-  hsProp[VARIATIONS_COUNT] = min(numVariations, maxVariations);
+  jprops[VARIATIONS_COUNT] = min(numVariations, MAX_VARIATIONS);
   if(numVariations != DEFAULT_VARIATION)
-    hsProp[VARIATIONS_ADDRESS] = "0x" + Base::toString(info.varsAddr, Base::Fmt::_16);
+    jprops[VARIATIONS_ADDRESS] = "0x" + Base::toString(info.varsAddr, Base::Fmt::_16);
   if(info.varsBCD != DEFAULT_VARS_BCD)
-    hsProp[VARIATIONS_BCD] = info.varsBCD;
+    jprops[VARIATIONS_BCD] = info.varsBCD;
   if(info.varsZeroBased != DEFAULT_VARS_ZERO_BASED)
-    hsProp[VARIATIONS_ZERO_BASED] = info.varsZeroBased;
+    jprops[VARIATIONS_ZERO_BASED] = info.varsZeroBased;
 
   // handle score
   if(info.numDigits != DEFAULT_DIGITS)
-    hsProp[SCORE_DIGITS] = info.numDigits;
+    jprops[SCORE_DIGITS] = info.numDigits;
   if(info.trailingZeroes != DEFAULT_TRAILING)
-    hsProp[SCORE_TRAILING_ZEROES] = info.trailingZeroes;
+    jprops[SCORE_TRAILING_ZEROES] = info.trailingZeroes;
   if(info.scoreBCD != DEFAULT_SCORE_BCD)
-    hsProp[SCORE_BCD] = info.scoreBCD;
+    jprops[SCORE_BCD] = info.scoreBCD;
   if(info.scoreInvert != DEFAULT_SCORE_REVERSED)
-    hsProp[SCORE_INVERTED] = info.scoreInvert;
-  uInt32 addrBytes = numAddrBytes(info.numDigits, info.trailingZeroes);
+    jprops[SCORE_INVERTED] = info.scoreInvert;
 
+  uInt32 addrBytes = numAddrBytes(info.numDigits, info.trailingZeroes);
   json addresses = json::array();
+
   for(uInt32 a = 0; a < addrBytes; ++a)
     addresses.push_back("0x" + Base::toString(info.scoreAddr[a], Base::Fmt::_16));
-  hsProp[SCORE_ADDRESSES] = addresses;
+  jprops[SCORE_ADDRESSES] = addresses;
 
   // handle special
   if(!info.special.empty())
-    hsProp[SPECIAL_LABEL] = info.special;
+    jprops[SPECIAL_LABEL] = info.special;
   if(!info.special.empty())
-    hsProp[SPECIAL_ADDRESS] = "0x" + Base::toString(info.specialAddr, Base::Fmt::_16);
+    jprops[SPECIAL_ADDRESS] = "0x" + Base::toString(info.specialAddr, Base::Fmt::_16);
   if(info.specialBCD != DEFAULT_SPECIAL_BCD)
-    hsProp[SPECIAL_BCD] = info.specialBCD;
+    jprops[SPECIAL_BCD] = info.specialBCD;
   if(info.specialZeroBased != DEFAULT_SPECIAL_ZERO_BASED)
-    hsProp[SPECIAL_ZERO_BASED] = info.specialZeroBased;
+    jprops[SPECIAL_ZERO_BASED] = info.specialZeroBased;
 
   // handle notes
   if(!info.notes.empty())
-    hsProp[NOTES] = info.notes;
+    jprops[NOTES] = info.notes;
 
   //if(info.armRAM != DEFAULT_ARM_RAM)
-  //  hsProp[""] = info.armRAM ? "1" : "0"; // TODO add ',' to numDigits!
+  //  jprops[""] = info.armRAM;
 
-  props.set(PropType::Cart_Highscore, hsProp.dump());
-
-
-
-  ostringstream buf;
-  string output;
-
-  props.set(PropType::Cart_Variations, to_string(min(numVariations, maxVariations)));
-
-  // fill from the back to skip default values
-  if (output.length() || !info.notes.empty())
-    output.insert(0, "," + toPropString(info.notes));
-
-  if (output.length() || info.specialZeroBased != DEFAULT_SPECIAL_ZERO_BASED)
-    output.insert(0, info.specialZeroBased ? ",1" : ",0");
-  if (output.length() || info.specialBCD != DEFAULT_SPECIAL_BCD)
-    output.insert(0, info.specialBCD ? ",B" : ",D");
-  if (output.length() || !info.special.empty())
-    output.insert(0, "," + toPropString(info.special.empty() ? "_" : info.special));
-
-  if (output.length() || info.varsZeroBased != DEFAULT_VARS_ZERO_BASED)
-    output.insert(0, info.varsZeroBased ? ",1" : ",0");
-  if (output.length() || info.varsBCD != DEFAULT_VARS_BCD)
-    output.insert(0, info.varsBCD ? ",B" : ",D");
-
-  if (output.length() || info.scoreInvert != DEFAULT_SCORE_REVERSED)
-    output.insert(0, info.scoreInvert ? ",1" : ",0");
-  if (output.length() || info.scoreBCD != DEFAULT_SCORE_BCD)
-    output.insert(0, info.scoreBCD ? ",B" : ",H");
-  if (output.length() || info.trailingZeroes != DEFAULT_TRAILING)
-    output.insert(0, "," + to_string(info.trailingZeroes));
-  if (output.length() || info.numDigits != DEFAULT_DIGITS)
-    output.insert(0, to_string(info.numDigits));
-  //if (output.length() || info.armRAM != DEFAULT_ARM_RAM)
-  //  output.insert(0, info.armRAM ? "1" : "0"); // TODO add ',' to numDigits!
-
-  props.set(PropType::Cart_Formats, output);
-
-  for (uInt32 a = 0; a < numAddrBytes(info.numDigits, info.trailingZeroes); ++a)
-    buf << hex << info.scoreAddr[a] << ",";
-
-  // add optional addresses
-  if (numVariations != DEFAULT_VARIATION || !info.special.empty())
-    buf << info.varsAddr << "," ;
-  if (!info.special.empty())
-    buf << info.specialAddr << "," ;
-
-  output = buf.str();
-  output.pop_back();
-  props.set(PropType::Cart_Addresses, output);
+  props.set(PropType::Cart_Highscore, jprops.dump());
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-uInt32 HighScoresManager::numDigits(const Properties& props) const
+uInt32 HighScoresManager::numDigits(const json& jprops) const
 {
-  return min(getPropInt(props, SCORE_DIGITS, DEFAULT_DIGITS), MAX_SCORE_DIGITS);
-
-  //string digits = getPropIdx(props, PropType::Cart_Formats, IDX_SCORE_DIGITS);
-  //uInt32 maxScoreDigits = MAX_SCORE_DIGITS;
-
-  //return min(uInt32(stringToInt(digits, DEFAULT_DIGITS)), maxScoreDigits);
+  return min(getPropInt(jprops, SCORE_DIGITS, DEFAULT_DIGITS), MAX_SCORE_DIGITS);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-uInt32 HighScoresManager::trailingZeroes(const Properties& props) const
+uInt32 HighScoresManager::trailingZeroes(const json& jprops) const
 {
-  return min(getPropInt(props, SCORE_TRAILING_ZEROES, DEFAULT_TRAILING), MAX_TRAILING);
-
-  //string trailing = getPropIdx(props, PropType::Cart_Formats, IDX_TRAILING_ZEROES);
-  //const uInt32 maxTrailing = MAX_TRAILING;
-
-  //return min(uInt32(stringToInt(trailing, DEFAULT_TRAILING)), maxTrailing);
+  return min(getPropInt(jprops, SCORE_TRAILING_ZEROES, DEFAULT_TRAILING), MAX_TRAILING);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool HighScoresManager::scoreBCD(const Properties& props) const
+bool HighScoresManager::scoreBCD(const json& jprops) const
 {
-  return getPropBool(props, SCORE_BCD, DEFAULT_SCORE_BCD);
-
-  //string bcd = getPropIdx(props, PropType::Cart_Formats, IDX_SCORE_BCD);
-
-  //return bcd.empty() ? DEFAULT_SCORE_BCD : bcd == "B";
-}
-
-bool HighScoresManager::scoreInvert(const Properties& props) const
-{
-  return getPropBool(props, SCORE_INVERTED, DEFAULT_SCORE_REVERSED);
-
-  //string reversed = getPropIdx(props, PropType::Cart_Formats, IDX_SCORE_INVERT);
-
-  //return reversed.empty() ? DEFAULT_SCORE_REVERSED : reversed != "0";
+  return getPropBool(jprops, SCORE_BCD, DEFAULT_SCORE_BCD);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool HighScoresManager::varBCD(const Properties& props) const
+bool HighScoresManager::scoreInvert(const json& jprops) const
 {
-  return getPropBool(props, VARIATIONS_BCD, DEFAULT_VARS_BCD);
-
-  //string bcd = getPropIdx(props, PropType::Cart_Formats, IDX_VAR_BCD);
-
-  //return bcd.empty() ? DEFAULT_VARS_BCD : bcd == "B";
+  return getPropBool(jprops, SCORE_INVERTED, DEFAULT_SCORE_REVERSED);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool HighScoresManager::varZeroBased(const Properties& props) const
+bool HighScoresManager::varBCD(const json& jprops) const
 {
-  return getPropBool(props, VARIATIONS_ZERO_BASED, DEFAULT_VARS_ZERO_BASED);
-
-  //string zeroBased = getPropIdx(props, PropType::Cart_Formats, IDX_VAR_ZERO_BASED);
-
-  //return zeroBased.empty() ? DEFAULT_VARS_ZERO_BASED : zeroBased != "0";
+  return getPropBool(jprops, VARIATIONS_BCD, DEFAULT_VARS_BCD);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string HighScoresManager::specialLabel(const Properties& props) const
+bool HighScoresManager::varZeroBased(const json& jprops) const
 {
-  return getPropStr(props, SPECIAL_LABEL);
-
-  //return fromPropString(getPropIdx(props, PropType::Cart_Formats, IDX_SPECIAL_LABEL));
+  return getPropBool(jprops, VARIATIONS_ZERO_BASED, DEFAULT_VARS_ZERO_BASED);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool HighScoresManager::specialBCD(const Properties& props) const
+const string HighScoresManager::specialLabel(const json& jprops) const
 {
-  return getPropBool(props, SPECIAL_BCD, DEFAULT_SPECIAL_BCD);
-
-  //string bcd = getPropIdx(props, PropType::Cart_Formats, IDX_SPECIAL_BCD);
-
-  //return bcd.empty() ? DEFAULT_SPECIAL_BCD : bcd == "B";
+  return getPropStr(jprops, SPECIAL_LABEL);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool HighScoresManager::specialZeroBased(const Properties& props) const
+bool HighScoresManager::specialBCD(const json& jprops) const
 {
-  return getPropBool(props, SPECIAL_ZERO_BASED, DEFAULT_SPECIAL_ZERO_BASED);
-
-  //string zeroBased = getPropIdx(props, PropType::Cart_Formats, IDX_SPECIAL_ZERO_BASED);
-
-  //return zeroBased.empty() ? DEFAULT_SPECIAL_ZERO_BASED : zeroBased != "0";
+  return getPropBool(jprops, SPECIAL_BCD, DEFAULT_SPECIAL_BCD);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string HighScoresManager::notes(const Properties& props) const
+bool HighScoresManager::specialZeroBased(const json& jprops) const
 {
-  return getPropStr(props, NOTES);
-
-  //return fromPropString(getPropIdx(props, PropType::Cart_Formats, IDX_NOTES));
+  return getPropBool(jprops, SPECIAL_ZERO_BASED, DEFAULT_SPECIAL_ZERO_BASED);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-/*bool HighScoresManager::armRAM(const Properties& props) const
+const string HighScoresManager::notes(const json& jprops) const
 {
-  //string armRAM = getPropIdx(props, PropType::Cart_Formats, IDX_ARM_RAM);
+  return getPropStr(jprops, NOTES);
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+/*bool HighScoresManager::armRAM(const json& jprops) const
+{
+  //string armRAM = getPropIdx(jprops, PropType::Cart_Formats, IDX_ARM_RAM);
 
   //return armRAM.empty() ? DEFAULT_ARM_RAM : armRAM != "0";
   return false;
 }*/
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-uInt16 HighScoresManager::varAddress(const Properties& props) const
+uInt16 HighScoresManager::varAddress(const json& jprops) const
 {
-  return getPropAddr(props, VARIATIONS_ADDRESS, DEFAULT_ADDRESS);
-
-  //uInt32 idx = numAddrBytes(props) + IDX_VARS_ADDRESS;
-  //string addr = getPropIdx(props, PropType::Cart_Addresses, idx);
-
-  //return stringToIntBase16(addr, DEFAULT_ADDRESS);
+  return getPropAddr(jprops, VARIATIONS_ADDRESS, DEFAULT_ADDRESS);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-uInt16 HighScoresManager::specialAddress(const Properties& props) const
+uInt16 HighScoresManager::specialAddress(const json& jprops) const
 {
-  return getPropAddr(props, SPECIAL_ADDRESS, DEFAULT_ADDRESS);
-
-  //uInt32 idx = numAddrBytes(props) + IDX_SPECIAL_ADDRESS;
-  //string addr = getPropIdx(props, PropType::Cart_Addresses, idx);
-
-  //return stringToIntBase16(addr, DEFAULT_ADDRESS);
+  return getPropAddr(jprops, SPECIAL_ADDRESS, DEFAULT_ADDRESS);
 }
 
-
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 uInt32 HighScoresManager::numAddrBytes(Int32 digits, Int32 trailing) const
 {
@@ -415,26 +311,26 @@ uInt32 HighScoresManager::numAddrBytes(Int32 digits, Int32 trailing) const
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-uInt32 HighScoresManager::numAddrBytes(const Properties& props) const
+uInt32 HighScoresManager::numAddrBytes(const json& jprops) const
 {
-  return numAddrBytes(numDigits(props), trailingZeroes(props));
+  return numAddrBytes(numDigits(jprops), trailingZeroes(jprops));
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 Int32 HighScoresManager::numVariations() const
 {
-  Properties props;
-  uInt16 vars = numVariations(properties(props));
+  json jprops;
+  uInt16 vars = numVariations(properties(jprops));
 
   return vars;;
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string HighScoresManager::specialLabel() const
+const string HighScoresManager::specialLabel() const
 {
-  Properties props;
+  json jprops;
 
-  return specialLabel(properties(props));
+  return specialLabel(properties(jprops));
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -452,8 +348,8 @@ Int32 HighScoresManager::variation(uInt16 addr, bool varBCD, bool zeroBased,
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 Int32 HighScoresManager::variation() const
 {
-  Properties props;
-  uInt16 addr = varAddress(properties(props));
+  json jprops;
+  uInt16 addr = varAddress(properties(jprops));
 
   if(addr == DEFAULT_ADDRESS) {
     if(numVariations() == 1)
@@ -462,7 +358,7 @@ Int32 HighScoresManager::variation() const
       return NO_VALUE;
   }
 
-  return variation(addr, varBCD(props), varZeroBased(props), numVariations(props));
+  return variation(addr, varBCD(jprops), varZeroBased(jprops), numVariations(jprops));
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -501,73 +397,26 @@ Int32 HighScoresManager::score(uInt32 numAddrBytes, uInt32 trailingZeroes,
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 Int32 HighScoresManager::score() const
 {
-  Properties props;
-  uInt32 numBytes = numAddrBytes(properties(props));
-  ScoreAddresses scoreAddr;
+  json jprops;
+  uInt32 numBytes = numAddrBytes(properties(jprops));
+  const ScoreAddresses scoreAddr = getPropScoreAddr(jprops);
 
-  if(numBytes >= 1)
-  {
-    string addr = getPropStr(props, SCORE_ADDRESS_0);
-
-    if(addr.empty())
-      return NO_VALUE;
-
-    scoreAddr[0] = getPropAddr(props, SCORE_ADDRESS_0);
-  }
-
-  if(numBytes >= 2)
-  {
-    string addr = getPropStr(props, SCORE_ADDRESS_1);
-
-    if(addr.empty())
-      return NO_VALUE;
-
-    scoreAddr[1] = getPropAddr(props, SCORE_ADDRESS_1);
-  }
-
-  if(numBytes >= 3)
-  {
-    string addr = getPropStr(props, SCORE_ADDRESS_2);
-
-    if(addr.empty())
-      return NO_VALUE;
-
-    scoreAddr[2] = getPropAddr(props, SCORE_ADDRESS_2);
-  }
-
-  if(numBytes >= 4)
-  {
-    string addr = getPropStr(props, SCORE_ADDRESS_3);
-
-    if(addr.empty())
-      return NO_VALUE;
-
-    scoreAddr[3] = getPropAddr(props, SCORE_ADDRESS_3);
-  }
-
-  //for (uInt32 b = 0; b < numBytes; ++b)
-  //{
-  //  string addr = getPropIdx(props, PropType::Cart_Addresses, b);
-
-  //  if (addr.empty())
-  //    return NO_VALUE;
-  //  scoreAddr[b] = stringToIntBase16(addr);
-  //}
-
-  return score(numBytes, trailingZeroes(props), scoreBCD(props), scoreAddr);
+  if(uInt32(scoreAddr.size()) < numBytes)
+    return NO_VALUE;
+  return score(numBytes, trailingZeroes(jprops), scoreBCD(jprops), scoreAddr);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string HighScoresManager::formattedScore(Int32 score, Int32 width) const
+const string HighScoresManager::formattedScore(Int32 score, Int32 width) const
 {
   if(score <= 0)
     return "";
 
   ostringstream buf;
-  Properties props;
-  Int32 digits = numDigits(properties(props));
+  json jprops;
+  Int32 digits = numDigits(properties(jprops));
 
-  if(scoreBCD(props))
+  if(scoreBCD(jprops))
   {
     if(width > digits)
       digits = width;
@@ -584,20 +433,20 @@ string HighScoresManager::formattedScore(Int32 score, Int32 width) const
 
 bool HighScoresManager::scoreInvert() const
 {
-  Properties props;
-  return scoreInvert(properties(props));
+  json jprops;
+  return scoreInvert(properties(jprops));
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 Int32 HighScoresManager::special() const
 {
-  Properties props;
-  uInt16 addr = specialAddress(properties(props));
+  json jprops;
+  uInt16 addr = specialAddress(properties(jprops));
 
   if (addr == DEFAULT_ADDRESS)
     return NO_VALUE;
 
-  return special(addr, specialBCD(props), specialZeroBased(props));
+  return special(addr, specialBCD(jprops), specialZeroBased(jprops));
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -617,11 +466,11 @@ Int32 HighScoresManager::special(uInt16 addr, bool varBCD, bool zeroBased) const
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string HighScoresManager::notes() const
+const string HighScoresManager::notes() const
 {
-  Properties props;
+  json jprops;
 
-  return notes(properties(props));
+  return notes(properties(jprops));
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -657,56 +506,63 @@ void replaceAll(std::string& str, const std::string& from, const std::string& to
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool HighScoresManager::getPropBool(const Properties& props, const string& key,
+bool HighScoresManager::getPropBool(const json& jprops, const string& key,
                                     bool defVal) const
 {
-  const string& property = props.get(PropType::Cart_Highscore);
+  return jprops.contains(key) ? jprops.at(key).get<bool>() : defVal;
+}
 
-  if(property.empty())
-    return defVal;
 
-  const json hsProp = json::parse(property);
-
-  return hsProp.contains(key) ? hsProp.at(key).get<bool>() : defVal;
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+uInt32 HighScoresManager::getPropInt(const json& jprops, const string& key,
+                                     uInt32 defVal) const
+{
+  return jprops.contains(key) ? jprops.at(key).get<uInt32>() : defVal;
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-uInt32 HighScoresManager::getPropInt(const Properties& props, const string& key,
-                                      uInt32 defVal) const
+const string HighScoresManager::getPropStr(const json& jprops, const string& key,
+                                           const string& defVal) const
 {
-  const string& property = props.get(PropType::Cart_Highscore);
-
-  if(property.empty())
-    return defVal;
-
-  const json hsProp = json::parse(property);
-
-  return hsProp.contains(key) ? hsProp.at(key).get<uInt32>() : defVal;
+  return jprops.contains(key) ? jprops.at(key).get<string>() : defVal;
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string HighScoresManager::getPropStr(const Properties& props, const string& key,
-                                     const string& defVal) const
+uInt16 HighScoresManager::getPropAddr(const json& jprops, const string& key,
+                                      uInt16 defVal) const
 {
-  const string& property = props.get(PropType::Cart_Highscore);
-
-  if(property.empty())
-    return defVal;
-
-  const json hsProp = json::parse(property);
-
-  return hsProp.contains(key) ? hsProp.at(key).get<string>() : defVal;
-}
-
-// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-uInt16 HighScoresManager::getPropAddr(const Properties& props, const string& key,
-                                     uInt16 defVal) const
-{
-  const string str = getPropStr(props, key);
+  const string str = getPropStr(jprops, key);
 
   return str.empty() ? defVal : fromHexStr(str);
 }
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+const HSM::ScoreAddresses HighScoresManager::getPropScoreAddr(const json& jprops) const
+{
+  ScoreAddresses scoreAddr{};
+
+  if(jprops.contains(SCORE_ADDRESSES))
+  {
+    const json addrProps = jprops.at(SCORE_ADDRESSES);
+
+    if(!addrProps.empty() && addrProps.is_array())
+    {
+      int a = 0;
+
+      for(const json& addresses : addrProps)
+      {
+        const string address = addresses.get<string>();
+
+        if(address.empty())
+          scoreAddr[a++] = DEFAULT_ADDRESS;
+        else
+          scoreAddr[a++] = fromHexStr(address);
+      }
+    }
+  }
+  return scoreAddr;
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 uInt16 HighScoresManager::fromHexStr(const string& addr) const
 {
@@ -728,42 +584,6 @@ Int32 HighScoresManager::fromBCD(uInt8 bcd) const
   return (bcd >> 4) * 10 + bcd % 16;
 }
 
-// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string HighScoresManager::toPropString(const string& text) const
-{
-  string result = text;
-  size_t pos;
-
-  while ((pos = result.find(" ")) != std::string::npos) {
-    result.replace(pos, 1, "_");
-  }
-
-  return result;
-}
-
-// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string HighScoresManager::fromPropString(const string& text) const
-{
-  string result = text;
-  size_t pos;
-
-  while ((pos = result.find("_")) != std::string::npos) {
-    result.replace(pos, 1, " ");
-  }
-
-  // some ugly formatting
-  if(result.length())
-  {
-    char first = result[0];
-    result = BSPF::toLowerCase(result);
-    result[0] = first;
-  }
-
-  // remove leading spaces (especially for empty values)
-  size_t start = result.find_first_not_of(" ");
-  return (start == std::string::npos) ? "" : result.substr(start);
-}
-
 const string HighScoresManager::VARIATIONS_COUNT = "variations_number";
 const string HighScoresManager::VARIATIONS_ADDRESS = "variations_address";
 const string HighScoresManager::VARIATIONS_BCD = "variations_bcd";
@@ -773,10 +593,6 @@ const string HighScoresManager::SCORE_TRAILING_ZEROES = "score_trailing_zeroes";
 const string HighScoresManager::SCORE_BCD = "score_bcd";
 const string HighScoresManager::SCORE_INVERTED = "score_inverted";
 const string HighScoresManager::SCORE_ADDRESSES = "score_addresses";
-const string HighScoresManager::SCORE_ADDRESS_0 = "score_address_0";
-const string HighScoresManager::SCORE_ADDRESS_1 = "score_address_1";
-const string HighScoresManager::SCORE_ADDRESS_2 = "score_address_2";
-const string HighScoresManager::SCORE_ADDRESS_3 = "score_address_3";
 const string HighScoresManager::SPECIAL_LABEL = "special_label";
 const string HighScoresManager::SPECIAL_ADDRESS = "special_address";
 const string HighScoresManager::SPECIAL_BCD = "special_bcd";
diff --git a/src/common/HighScoresManager.hxx b/src/common/HighScoresManager.hxx
index 969555fbc..ede42e0f0 100644
--- a/src/common/HighScoresManager.hxx
+++ b/src/common/HighScoresManager.hxx
@@ -21,6 +21,9 @@
 class OSystem;
 
 #include "Props.hxx"
+#include "json.hxx"
+
+using json = nlohmann::json;
 
 /**
   This class provides an interface to all things related to high scores.
@@ -92,15 +95,6 @@ class HighScoresManager
     void set(Properties& props, uInt32 numVariations,
              const HSM::ScoresInfo& info) const;
 
-    /**
-      Calculate the number of bytes for one player's score from given parameters
-
-      @return The number of score address bytes
-    */
-    uInt32 numAddrBytes(Int32 digits, Int32 trailing) const;
-
-    // Retrieve current values from (using given parameters)
-    Int32 variation(uInt16 addr, bool varBCD, bool zeroBased, uInt32 numVariations) const;
     /**
       Calculate the score from given parameters
 
@@ -109,44 +103,34 @@ class HighScoresManager
     Int32 score(uInt32 numAddrBytes, uInt32 trailingZeroes, bool isBCD,
                 const HSM::ScoreAddresses& scoreAddr) const;
 
+    // Convert the given value, using only the maximum bits required by maxVal
+    //  and adjusted for BCD and zero based data
+    Int32 convert(Int32 val, uInt32 maxVal, bool isBCD, bool zeroBased) const;
+
+    /**
+      Calculate the number of bytes for one player's score from given parameters
+
+      @return The number of score address bytes
+    */
+    uInt32 numAddrBytes(Int32 digits, Int32 trailing) const;
+
+
     Int32 special(uInt16 addr, bool varBCD, bool zeroBased) const;
 
     // Retrieve current values (using game's properties)
     Int32 numVariations() const;
-    string specialLabel() const;
+    const string specialLabel() const;
     Int32 variation() const;
     Int32 score() const;
-    string formattedScore(Int32 score, Int32 width = -1) const;
+    const string formattedScore(Int32 score, Int32 width = -1) const;
     bool scoreInvert() const;
     Int32 special() const;
-    string notes() const;
-
-    // converts the given value, using only the maximum bits required by maxVal
-    //  and adjusted for BCD and zero based data
-    Int32 convert(Int32 val, uInt32 maxVal, bool isBCD, bool zeroBased) const;
+    const string notes() const;
 
     // Peek into memory
     Int16 peek(uInt16 addr) const;
 
   private:
-    //enum {
-    //  //IDX_ARM_RAM = 0,
-    //  IDX_SCORE_DIGITS = 0,
-    //  IDX_TRAILING_ZEROES,
-    //  IDX_SCORE_BCD,
-    //  IDX_SCORE_INVERT,
-    //  IDX_VAR_BCD,
-    //  IDX_VAR_ZERO_BASED,
-    //  IDX_SPECIAL_LABEL,
-    //  IDX_SPECIAL_BCD,
-    //  IDX_SPECIAL_ZERO_BASED,
-    //  IDX_NOTES,
-    //};
-    //enum {
-    //  IDX_VARS_ADDRESS = 0,
-    //  IDX_SPECIAL_ADDRESS
-    //};
-
     static const string VARIATIONS_COUNT;
     static const string VARIATIONS_ADDRESS;
     static const string VARIATIONS_BCD;
@@ -156,10 +140,6 @@ class HighScoresManager
     static const string SCORE_BCD;
     static const string SCORE_INVERTED;
     static const string SCORE_ADDRESSES;
-    static const string SCORE_ADDRESS_0;
-    static const string SCORE_ADDRESS_1;
-    static const string SCORE_ADDRESS_2;
-    static const string SCORE_ADDRESS_3;
     static const string SPECIAL_LABEL;
     static const string SPECIAL_ADDRESS;
     static const string SPECIAL_BCD;
@@ -180,44 +160,45 @@ class HighScoresManager
     static constexpr bool DEFAULT_SPECIAL_ZERO_BASED = false;
 
   private:
-    // Get individual highscore info from properties
-    uInt32 numVariations(const Properties& props) const;
-    uInt16 varAddress(const Properties& props) const;
-    uInt16 specialAddress(const Properties& props) const;
-    uInt32 numDigits(const Properties& props) const;
-    uInt32 trailingZeroes(const Properties& props) const;
-    bool scoreBCD(const Properties& props) const;
-    bool scoreInvert(const Properties& props) const;
-    bool varBCD(const Properties& props) const;
-    bool varZeroBased(const Properties& props) const;
-    string specialLabel(const Properties& props) const;
-    bool specialBCD(const Properties& props) const;
-    bool specialZeroBased(const Properties& props) const;
-    string notes(const Properties& props) const;
-    //bool armRAM(const Properties& props) const;
+    // Retrieve current values from (using given parameters)
+    Int32 variation(uInt16 addr, bool varBCD, bool zeroBased, uInt32 numVariations) const;
 
+    // Get individual highscore info from properties
+    uInt32 numVariations(const json& jprops) const;
+    uInt16 varAddress(const json& jprops) const;
+    uInt16 specialAddress(const json& jprops) const;
+    uInt32 numDigits(const json& jprops) const;
+    uInt32 trailingZeroes(const json& jprops) const;
+    bool scoreBCD(const json& jprops) const;
+    bool scoreInvert(const json& jprops) const;
+    bool varBCD(const json& jprops) const;
+    bool varZeroBased(const json& jprops) const;
+    const string specialLabel(const json& jprops) const;
+    bool specialBCD(const json& jprops) const;
+    bool specialZeroBased(const json& jprops) const;
+    const string notes(const json& jprops) const;
+    //bool armRAM(const json& jprops) const;
 
     // Calculate the number of bytes for one player's score from property parameters
-    uInt32 numAddrBytes(const Properties& props) const;
+    uInt32 numAddrBytes(const json& jprops) const;
 
     // Get properties
-    Properties& properties(Properties& props) const;
-    //// Get value from highscore propterties at given index
-    //string getPropIdx(const Properties& props, PropType type, uInt32 idx = 0) const;
+    const json properties(const Properties& props) const;
+    json properties(json& jprops) const;
 
-    bool getPropBool(const Properties& props, const string& key,
+    // Get value from highscore properties for given key
+    bool getPropBool(const json& jprops, const string& key,
                      bool defVal = false) const;
-    uInt32 getPropInt(const Properties& props, const string& key,
+    uInt32 getPropInt(const json& jprops, const string& key,
                       uInt32 defVal = 0) const;
-    string getPropStr(const Properties& props, const string& key,
-                      const string& defVal = "") const;
-    uInt16 getPropAddr(const Properties& props, const string& key,
+    const string getPropStr(const json& jprops, const string& key,
+                            const string& defVal = "") const;
+    uInt16 getPropAddr(const json& jprops, const string& key,
                        uInt16 defVal = 0) const;
+    const HSM::ScoreAddresses getPropScoreAddr(const json& jprops) const;
 
     uInt16 fromHexStr(const string& addr) const;
     Int32 fromBCD(uInt8 bcd) const;
-    string toPropString(const string& test) const;
-    string fromPropString(const string& test) const;
 
   private:
     // Reference to the osystem object
diff --git a/src/common/JoyMap.cxx b/src/common/JoyMap.cxx
index e8fccf93b..db7ac6304 100644
--- a/src/common/JoyMap.cxx
+++ b/src/common/JoyMap.cxx
@@ -240,8 +240,7 @@ int JoyMap::loadMapping(const json& eventMappings, const EventMode mode)
       );
 
       i++;
-    }
-    catch(json::exception) {
+    } catch (const json::exception&) {
       Logger::error("ignoring invalid joystick event");
     }
   }
diff --git a/src/common/KeyMap.cxx b/src/common/KeyMap.cxx
index c9de296f5..c027827d6 100644
--- a/src/common/KeyMap.cxx
+++ b/src/common/KeyMap.cxx
@@ -22,6 +22,52 @@
 
 using json = nlohmann::json;
 
+namespace {
+  json serializeModkeyMask(int mask)
+  {
+    if(mask == StellaMod::KBDM_NONE) return json(nullptr);
+
+    json serializedMask = json::array();
+
+    for(StellaMod mod: {
+      StellaMod::KBDM_CTRL,
+      StellaMod::KBDM_SHIFT,
+      StellaMod::KBDM_ALT,
+      StellaMod::KBDM_GUI,
+      StellaMod::KBDM_LSHIFT,
+      StellaMod::KBDM_RSHIFT,
+      StellaMod::KBDM_LCTRL,
+      StellaMod::KBDM_RCTRL,
+      StellaMod::KBDM_LALT,
+      StellaMod::KBDM_RALT,
+      StellaMod::KBDM_LGUI,
+      StellaMod::KBDM_RGUI,
+      StellaMod::KBDM_NUM,
+      StellaMod::KBDM_CAPS,
+      StellaMod::KBDM_MODE,
+      StellaMod::KBDM_RESERVED
+    }) {
+      if((mask & mod) != mod) continue;
+
+      serializedMask.push_back(json(mod));
+      mask &= ~mod;
+    }
+
+    return serializedMask.size() == 1 ? serializedMask.at(0) : serializedMask;
+  }
+
+  int deserializeModkeyMask(json serializedMask)
+  {
+    if (serializedMask.is_null()) return StellaMod::KBDM_NONE;
+    if (!serializedMask.is_array()) return serializedMask.get<StellaMod>();
+
+    int mask = 0;
+    for(const json& mod: serializedMask) mask |= mod.get<StellaMod>();
+
+    return mask;
+  }
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void KeyMap::add(const Event::Type event, const Mapping& mapping)
 {
@@ -206,12 +252,11 @@ int KeyMap::loadMapping(const json& mappings, const EventMode mode) {
         mapping.at("event").get<Event::Type>(),
         mode,
         mapping.at("key").get<StellaKey>(),
-        mapping.contains("mod") ? mapping.at("mod").get<StellaMod>() : StellaMod::KBDM_NONE
+        mapping.contains("mod") ? deserializeModkeyMask(mapping.at("mod")) : StellaMod::KBDM_NONE
       );
 
       i++;
-    }
-    catch(json::exception) {
+    } catch (const json::exception&) {
       Logger::error("ignoring bad keyboard mapping");
     }
   }
diff --git a/src/common/PJoystickHandler.cxx b/src/common/PJoystickHandler.cxx
index 323caea1c..3b41cf854 100644
--- a/src/common/PJoystickHandler.cxx
+++ b/src/common/PJoystickHandler.cxx
@@ -47,7 +47,7 @@ PhysicalJoystickHandler::PhysicalJoystickHandler(
 
   try {
     mappings = json::parse(serializedMapping);
-  } catch (json::exception) {
+  } catch (const json::exception&) {
     Logger::info("converting legacy joystick mappings");
 
     mappings = convertLegacyMapping(serializedMapping);
@@ -217,7 +217,7 @@ void PhysicalJoystickHandler::mapStelladaptors(const string& saport)
   // We know there will be only two such devices (at most), since the logic
   // in setupJoysticks take care of that
   int saCount = 0;
-  int saOrder[NUM_PORTS] = { 1, 2 };
+  int saOrder[] = { 1, 2 };
   if(BSPF::equalsIgnoreCase(saport, "rl"))
   {
     saOrder[0] = 2; saOrder[1] = 1;
diff --git a/src/common/PKeyboardHandler.cxx b/src/common/PKeyboardHandler.cxx
index a9a5bc1a6..bf3284099 100644
--- a/src/common/PKeyboardHandler.cxx
+++ b/src/common/PKeyboardHandler.cxx
@@ -74,7 +74,7 @@ void PhysicalKeyboardHandler::loadSerializedMappings(const string& serializedMap
 
   try {
     mapping = json::parse(serializedMapping);
-  } catch (json::exception) {
+  } catch (const json::exception&) {
     Logger::info("converting legacy keyboard mappings");
 
     mapping = KeyMap::convertLegacyMapping(serializedMapping);
@@ -82,7 +82,7 @@ void PhysicalKeyboardHandler::loadSerializedMappings(const string& serializedMap
 
   try {
     myKeyMap.loadMapping(mapping, mode);
-  } catch (json::exception) {
+  } catch (const json::exception&) {
     Logger::error("ignoring bad keyboard mappings");
   }
 }
diff --git a/src/common/PaletteHandler.cxx b/src/common/PaletteHandler.cxx
index f13c18ab1..aa66f5985 100644
--- a/src/common/PaletteHandler.cxx
+++ b/src/common/PaletteHandler.cxx
@@ -22,6 +22,7 @@
 
 #include "PaletteHandler.hxx"
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 PaletteHandler::PaletteHandler(OSystem& system)
   : myOSystem(system)
 {
diff --git a/src/common/PhosphorHandler.hxx b/src/common/PhosphorHandler.hxx
index efc77cf58..89d0df3a9 100644
--- a/src/common/PhosphorHandler.hxx
+++ b/src/common/PhosphorHandler.hxx
@@ -38,7 +38,7 @@ class PhosphorHandler
 
       @return  Averaged value of the two RGB colors
     */
-    static inline uInt32 getPixel(const uInt32 c, const uInt32 p)
+    static constexpr uInt32 getPixel(const uInt32 c, const uInt32 p)
     {
       // Mix current calculated frame with previous displayed frame
       const uInt8 rc = static_cast<uInt8>(c >> 16),
diff --git a/src/common/PhysicalJoystick.cxx b/src/common/PhysicalJoystick.cxx
index 488d1f318..8cbb6a8d8 100644
--- a/src/common/PhysicalJoystick.cxx
+++ b/src/common/PhysicalJoystick.cxx
@@ -87,7 +87,7 @@ bool PhysicalJoystick::setMap(const json& map)
 
     try {
       joyMap.loadMapping(entry.value(), eventModeFromJsonName(entry.key()));
-    } catch (json::exception) {
+    } catch (const json::exception&) {
       Logger::error("ignoring invalid json mapping for " + entry.key());
     }
 
diff --git a/src/common/RewindManager.cxx b/src/common/RewindManager.cxx
index 044bc57e9..d6d277995 100644
--- a/src/common/RewindManager.cxx
+++ b/src/common/RewindManager.cxx
@@ -41,18 +41,15 @@ void RewindManager::setup()
 
   const string& prefix = myOSystem.settings().getBool("dev.settings") ? "dev." : "plr.";
 
-  // Work around a bug in XCode 11.2 with -O0 and -O1
-  const uInt32 maxBufSize = MAX_BUF_SIZE;
-
   // TODO - Add proper bounds checking (define constexpr variables for this)
   //        Use those bounds in DeveloperDialog too
   mySize = std::min<uInt32>(
-      myOSystem.settings().getInt(prefix + "tm.size"), maxBufSize);
+      myOSystem.settings().getInt(prefix + "tm.size"), MAX_BUF_SIZE);
   if(mySize != myStateList.capacity())
     resize(mySize);
 
   myUncompressed = std::min<uInt32>(
-      myOSystem.settings().getInt(prefix + "tm.uncompressed"), maxBufSize);
+      myOSystem.settings().getInt(prefix + "tm.uncompressed"), MAX_BUF_SIZE);
 
   myInterval = INTERVAL_CYCLES[0];
   for(int i = 0; i < NUM_INTERVALS; ++i)
diff --git a/src/common/tv_filters/AtariNTSC.hxx b/src/common/tv_filters/AtariNTSC.hxx
index eb75bce3d..087e7c579 100644
--- a/src/common/tv_filters/AtariNTSC.hxx
+++ b/src/common/tv_filters/AtariNTSC.hxx
@@ -232,7 +232,7 @@ class AtariNTSC
     }
 
     // Common ntsc macros
-    static inline constexpr void ATARI_NTSC_CLAMP( uInt32& io, uInt32 shift ) {
+    static constexpr void ATARI_NTSC_CLAMP( uInt32& io, uInt32 shift ) {
       uInt32 sub = io >> (9-(shift)) & atari_ntsc_clamp_mask;
       uInt32 clamp = atari_ntsc_clamp_add - sub;
       io |= clamp;
@@ -240,31 +240,31 @@ class AtariNTSC
       io &= clamp;
     }
 
-    static inline constexpr void RGB_TO_YIQ(float r, float g, float b,
+    static constexpr void RGB_TO_YIQ(float r, float g, float b,
         float& y, float& i, float& q) {
       y = r * 0.299F + g * 0.587F + b * 0.114F;
       i = r * 0.595716F - g * 0.274453F - b * 0.321263F;
       q = r * 0.211456F - g * 0.522591F + b * 0.311135F;
     }
-    static inline constexpr void YIQ_TO_RGB(float y, float i, float q,
+    static constexpr void YIQ_TO_RGB(float y, float i, float q,
         const float* to_rgb, int& ir, int& ig, int& ib) {
       ir = static_cast<int>(y + to_rgb[0] * i + to_rgb[1] * q);
       ig = static_cast<int>(y + to_rgb[2] * i + to_rgb[3] * q);
       ib = static_cast<int>(y + to_rgb[4] * i + to_rgb[5] * q);
     }
 
-    static inline constexpr uInt32 PACK_RGB( int r, int g, int b ) {
+    static constexpr uInt32 PACK_RGB( int r, int g, int b ) {
       return r << 21 | g << 11 | b << 1;
     }
 
     // Converted from C-style macros; I don't even pretend to understand the logic here :)
-    static inline constexpr int PIXEL_OFFSET1( int ntsc, int scaled ) {
+    static constexpr int PIXEL_OFFSET1( int ntsc, int scaled ) {
       return (kernel_size / 2 + ((ntsc) - (scaled) / rescale_out * rescale_in) +
         ((((scaled) + rescale_out * 10) % rescale_out) != 0) +
         (rescale_out - (((scaled) + rescale_out * 10) % rescale_out)) % rescale_out +
         (kernel_size * 2 * (((scaled) + rescale_out * 10) % rescale_out)));
     }
-    static inline constexpr int PIXEL_OFFSET2( int ntsc ) {
+    static constexpr int PIXEL_OFFSET2( int ntsc ) {
       return 1.0F - (((ntsc) + 100) & 2);
     }
 
diff --git a/src/debugger/BreakpointMap.hxx b/src/debugger/BreakpointMap.hxx
index 492f4ef10..9a77bf8c3 100644
--- a/src/debugger/BreakpointMap.hxx
+++ b/src/debugger/BreakpointMap.hxx
@@ -30,12 +30,12 @@
 class BreakpointMap
 {
   private:
-    static const uInt16 ADDRESS_MASK = 0x1fff;  // either 0x1fff or 0xffff (not needed then)
+    static constexpr uInt16 ADDRESS_MASK = 0x1fff;  // either 0x1fff or 0xffff (not needed then)
 
   public:
     // breakpoint flags
-    static const uInt32 ONE_SHOT = 1 << 0;      // used for 'trace' command
-    static const uInt8 ANY_BANK = 255;          // breakpoint valid in any bank
+    static constexpr uInt32 ONE_SHOT = 1 << 0;      // used for 'trace' command
+    static constexpr uInt8 ANY_BANK = 255;          // breakpoint valid in any bank
 
     struct Breakpoint
     {
diff --git a/src/debugger/Debugger.hxx b/src/debugger/Debugger.hxx
index 6a53238bb..f937d2b52 100644
--- a/src/debugger/Debugger.hxx
+++ b/src/debugger/Debugger.hxx
@@ -76,9 +76,6 @@ class Debugger : public DialogContainer
     Debugger(OSystem& osystem, Console& console);
     ~Debugger() override;
 
-  private:
-    static const Int8 ANY_BANK = -1;
-
   public:
     /**
       Initialize the debugger dialog container.
@@ -284,8 +281,6 @@ class Debugger : public DialogContainer
     */
     Dialog* baseDialog() override { return myDialog; }
 
-    static const Int32 NOT_FOUND = -1;
-
   private:
     /**
       Save state of each debugger subsystem and, by default, mark all
@@ -367,6 +362,8 @@ class Debugger : public DialogContainer
     static std::array<BuiltinFunction, 18> ourBuiltinFunctions;
     static std::array<PseudoRegister, 16> ourPseudoRegisters;
 
+    static constexpr Int8 ANY_BANK = -1;
+
   private:
     // rewind/unwind n states
     uInt16 windStates(uInt16 numStates, bool unwind, string& message);
diff --git a/src/emucore/EventHandlerConstants.hxx b/src/emucore/EventHandlerConstants.hxx
index 7fc1e9411..2e65ad00d 100644
--- a/src/emucore/EventHandlerConstants.hxx
+++ b/src/emucore/EventHandlerConstants.hxx
@@ -75,8 +75,6 @@ enum JoyHatMask {
   EVENT_HATCENTER_M = 1<<4
 };
 
-static const int NUM_PORTS = 2;
-
 enum class EventMode {
   kEmulationMode, // active mapping used for emulation
   kMenuMode,      // mapping used for dialogs
diff --git a/src/emucore/MT24LC256.cxx b/src/emucore/MT24LC256.cxx
index ba6d2348b..53004b804 100644
--- a/src/emucore/MT24LC256.cxx
+++ b/src/emucore/MT24LC256.cxx
@@ -64,11 +64,8 @@ MT24LC256::MT24LC256(const FilesystemNode& eepromfile, const System& system,
 
   if(!fileValid)
   {
-    // Work around a bug in XCode 11.2 with -O0 and -O1
-    const uInt8 initialValue = INITIAL_VALUE;
-
     myData = make_unique<uInt8[]>(FLASH_SIZE);
-    std::fill_n(myData.get(), FLASH_SIZE, initialValue);
+    std::fill_n(myData.get(), FLASH_SIZE, INITIAL_VALUE);
     myDataChanged = true;
    }
 
@@ -142,24 +139,18 @@ void MT24LC256::systemReset()
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void MT24LC256::eraseAll()
 {
-  // Work around a bug in XCode 11.2 with -O0 and -O1
-  const uInt8 initialValue = INITIAL_VALUE;
-
-  std::fill_n(myData.get(), FLASH_SIZE, initialValue);
+  std::fill_n(myData.get(), FLASH_SIZE, INITIAL_VALUE);
   myDataChanged = true;
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void MT24LC256::eraseCurrent()
 {
-  // Work around a bug in XCode 11.2 with -O0 and -O1
-  const uInt8 initialValue = INITIAL_VALUE;
-
   for(uInt32 page = 0; page < PAGE_NUM; ++page)
   {
     if(myPageHit[page])
     {
-      std::fill_n(myData.get() + page * PAGE_SIZE, PAGE_SIZE, initialValue);
+      std::fill_n(myData.get() + page * PAGE_SIZE, PAGE_SIZE, INITIAL_VALUE);
       myDataChanged = true;
     }
   }
diff --git a/src/gui/DeveloperDialog.hxx b/src/gui/DeveloperDialog.hxx
index e3d31ecfd..fc16e302e 100644
--- a/src/gui/DeveloperDialog.hxx
+++ b/src/gui/DeveloperDialog.hxx
@@ -81,10 +81,10 @@ class DeveloperDialog : public Dialog
     enum SettingsSet { player = 0, developer = 1 };
 
     // MUST be aligned with RewindManager!
-    static const int NUM_INTERVALS = 7;
-    static const int NUM_HORIZONS = 8;
+    static constexpr int NUM_INTERVALS = 7;
+    static constexpr int NUM_HORIZONS = 8;
 
-    static const int DEBUG_COLORS = 6;
+    static constexpr int DEBUG_COLORS = 6;
 
     TabWidget* myTab{nullptr};
     // Emulator widgets
diff --git a/src/gui/TabWidget.hxx b/src/gui/TabWidget.hxx
index 141b29497..9d6f0837d 100644
--- a/src/gui/TabWidget.hxx
+++ b/src/gui/TabWidget.hxx
@@ -26,8 +26,8 @@
 class TabWidget : public Widget, public CommandSender
 {
   public:
-    static const int NO_WIDTH = 0;
-    static const int AUTO_WIDTH = -1;
+    static constexpr int NO_WIDTH = 0;
+    static constexpr int AUTO_WIDTH = -1;
 
     enum {
       kTabChangedCmd = 'TBCH'
diff --git a/src/macos/stella.xcodeproj/project.pbxproj b/src/macos/stella.xcodeproj/project.pbxproj
index d0892bdce..0a337371d 100644
--- a/src/macos/stella.xcodeproj/project.pbxproj
+++ b/src/macos/stella.xcodeproj/project.pbxproj
@@ -413,6 +413,8 @@
 		DC8078DB0B4BD5F3005E9305 /* DebuggerExpressions.hxx in Headers */ = {isa = PBXBuildFile; fileRef = DC8078DA0B4BD5F3005E9305 /* DebuggerExpressions.hxx */; };
 		DC8078EA0B4BD697005E9305 /* UIDialog.cxx in Sources */ = {isa = PBXBuildFile; fileRef = DC8078E60B4BD697005E9305 /* UIDialog.cxx */; };
 		DC8078EB0B4BD697005E9305 /* UIDialog.hxx in Headers */ = {isa = PBXBuildFile; fileRef = DC8078E70B4BD697005E9305 /* UIDialog.hxx */; };
+		DC816CF62572F92A00FBCCDA /* json.hxx in Headers */ = {isa = PBXBuildFile; fileRef = DC816CF42572F92A00FBCCDA /* json.hxx */; };
+		DC816CF72572F92A00FBCCDA /* json_lib.hxx in Headers */ = {isa = PBXBuildFile; fileRef = DC816CF52572F92A00FBCCDA /* json_lib.hxx */; };
 		DC84397B247B294E00C6A4FC /* CartTVBoy.hxx in Headers */ = {isa = PBXBuildFile; fileRef = DC843979247B294D00C6A4FC /* CartTVBoy.hxx */; };
 		DC84397C247B294E00C6A4FC /* CartTVBoy.cxx in Sources */ = {isa = PBXBuildFile; fileRef = DC84397A247B294D00C6A4FC /* CartTVBoy.cxx */; };
 		DC84397F247B297A00C6A4FC /* CartTVBoyWidget.hxx in Headers */ = {isa = PBXBuildFile; fileRef = DC84397D247B297A00C6A4FC /* CartTVBoyWidget.hxx */; };
@@ -520,7 +522,6 @@
 		DCB60ACC25430FC600A5C1D2 /* FBBackend.hxx in Headers */ = {isa = PBXBuildFile; fileRef = DCB60ACB25430FC600A5C1D2 /* FBBackend.hxx */; };
 		DCB60AD02543100900A5C1D2 /* FBBackendSDL2.cxx in Sources */ = {isa = PBXBuildFile; fileRef = DCB60ACD2543100900A5C1D2 /* FBBackendSDL2.cxx */; };
 		DCB60AD12543100900A5C1D2 /* FBBackendSDL2.hxx in Headers */ = {isa = PBXBuildFile; fileRef = DCB60ACE2543100900A5C1D2 /* FBBackendSDL2.hxx */; };
-		DCB60AD22543100900A5C1D2 /* audio in Resources */ = {isa = PBXBuildFile; fileRef = DCB60ACF2543100900A5C1D2 /* audio */; };
 		DCB87E581A104C1E00BF2A3B /* MediaFactory.hxx in Headers */ = {isa = PBXBuildFile; fileRef = DCB87E571A104C1E00BF2A3B /* MediaFactory.hxx */; };
 		DCBA539925557E2800087DD7 /* UndoHandler.hxx in Headers */ = {isa = PBXBuildFile; fileRef = DCBA539725557E2700087DD7 /* UndoHandler.hxx */; };
 		DCBA539A25557E2800087DD7 /* UndoHandler.cxx in Sources */ = {isa = PBXBuildFile; fileRef = DCBA539825557E2800087DD7 /* UndoHandler.cxx */; };
@@ -1182,6 +1183,8 @@
 		DC8078DA0B4BD5F3005E9305 /* DebuggerExpressions.hxx */ = {isa = PBXFileReference; fileEncoding = 30; lastKnownFileType = sourcecode.cpp.h; path = DebuggerExpressions.hxx; sourceTree = "<group>"; };
 		DC8078E60B4BD697005E9305 /* UIDialog.cxx */ = {isa = PBXFileReference; fileEncoding = 30; lastKnownFileType = sourcecode.cpp.cpp; path = UIDialog.cxx; sourceTree = "<group>"; };
 		DC8078E70B4BD697005E9305 /* UIDialog.hxx */ = {isa = PBXFileReference; fileEncoding = 30; lastKnownFileType = sourcecode.cpp.h; path = UIDialog.hxx; sourceTree = "<group>"; };
+		DC816CF42572F92A00FBCCDA /* json.hxx */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = json.hxx; sourceTree = "<group>"; };
+		DC816CF52572F92A00FBCCDA /* json_lib.hxx */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = json_lib.hxx; sourceTree = "<group>"; };
 		DC843979247B294D00C6A4FC /* CartTVBoy.hxx */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = CartTVBoy.hxx; sourceTree = "<group>"; };
 		DC84397A247B294D00C6A4FC /* CartTVBoy.cxx */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = CartTVBoy.cxx; sourceTree = "<group>"; };
 		DC84397D247B297A00C6A4FC /* CartTVBoyWidget.hxx */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = CartTVBoyWidget.hxx; sourceTree = "<group>"; };
@@ -1290,7 +1293,6 @@
 		DCB60ACB25430FC600A5C1D2 /* FBBackend.hxx */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = FBBackend.hxx; sourceTree = "<group>"; };
 		DCB60ACD2543100900A5C1D2 /* FBBackendSDL2.cxx */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = FBBackendSDL2.cxx; sourceTree = "<group>"; };
 		DCB60ACE2543100900A5C1D2 /* FBBackendSDL2.hxx */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = FBBackendSDL2.hxx; sourceTree = "<group>"; };
-		DCB60ACF2543100900A5C1D2 /* audio */ = {isa = PBXFileReference; lastKnownFileType = folder; path = audio; sourceTree = "<group>"; };
 		DCB87E571A104C1E00BF2A3B /* MediaFactory.hxx */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = MediaFactory.hxx; sourceTree = "<group>"; };
 		DCBA539725557E2700087DD7 /* UndoHandler.hxx */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = UndoHandler.hxx; sourceTree = "<group>"; };
 		DCBA539825557E2800087DD7 /* UndoHandler.cxx */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = UndoHandler.cxx; sourceTree = "<group>"; };
@@ -1563,6 +1565,7 @@
 				2D605130089879BA00C6DE89 /* debugger */,
 				2D6050CC0898776500C6DE89 /* emucore */,
 				2D6050FA0898786C00C6DE89 /* gui */,
+				DC816CF32572F8B400FBCCDA /* json */,
 				DCD6FC5A11C281A1005DA767 /* libpng */,
 				2D6050C60898771C00C6DE89 /* macos */,
 				2D6050C90898774B00C6DE89 /* unix */,
@@ -1773,7 +1776,6 @@
 			isa = PBXGroup;
 			children = (
 				DCC6A4AD20A2620D00863C59 /* audio */,
-				DCB60ACF2543100900A5C1D2 /* audio */,
 				E09F413A201E901D004A3391 /* AudioQueue.cxx */,
 				E09F4139201E901C004A3391 /* AudioQueue.hxx */,
 				E0FABEEA20E9948100EB8E28 /* AudioSettings.cxx */,
@@ -2274,6 +2276,15 @@
 			name = exception;
 			sourceTree = "<group>";
 		};
+		DC816CF32572F8B400FBCCDA /* json */ = {
+			isa = PBXGroup;
+			children = (
+				DC816CF52572F92A00FBCCDA /* json_lib.hxx */,
+				DC816CF42572F92A00FBCCDA /* json.hxx */,
+			);
+			path = json;
+			sourceTree = "<group>";
+		};
 		DCC467EA14FBEC9600E15508 /* tv_filters */ = {
 			isa = PBXGroup;
 			children = (
@@ -2533,6 +2544,7 @@
 				DCBD31E92299ADB400567357 /* Rect.hxx in Headers */,
 				DCBA539925557E2800087DD7 /* UndoHandler.hxx in Headers */,
 				2D91741A09BA90380026E9FF /* FSNode.hxx in Headers */,
+				DC816CF72572F92A00FBCCDA /* json_lib.hxx in Headers */,
 				2D91741B09BA90380026E9FF /* OSystem.hxx in Headers */,
 				DC6A18F919B3E65500DEB242 /* CartMDMWidget.hxx in Headers */,
 				2D91741F09BA90380026E9FF /* AboutBox.h in Headers */,
@@ -2743,6 +2755,7 @@
 				DCF8621A21C9D43300F95F52 /* StaggeredLogger.hxx in Headers */,
 				DCAAE5E31715887B0080BB82 /* CartF0Widget.hxx in Headers */,
 				DCAAE5E51715887B0080BB82 /* CartF4SCWidget.hxx in Headers */,
+				DC816CF62572F92A00FBCCDA /* json.hxx in Headers */,
 				DCAAE5E71715887B0080BB82 /* CartF4Widget.hxx in Headers */,
 				DC5963142139FA14002736F2 /* Bankswitch.hxx in Headers */,
 				DCAAE5E91715887B0080BB82 /* CartF6SCWidget.hxx in Headers */,
@@ -2876,7 +2889,6 @@
 				2D91747109BA90380026E9FF /* docs in Resources */,
 				2D91747209BA90380026E9FF /* AboutBox.nib in Resources */,
 				2DEFB40C09C3386F00754289 /* Cart.icns in Resources */,
-				DCB60AD22543100900A5C1D2 /* audio in Resources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};