diff --git a/src/engine/cmdStream.cpp b/src/engine/cmdStream.cpp
index 568f5ee0c..41c2c3cc8 100644
--- a/src/engine/cmdStream.cpp
+++ b/src/engine/cmdStream.cpp
@@ -704,7 +704,7 @@ bool DivCSPlayer::init() {
 
   // initialize state
   for (int i=0; i<e->getTotalChannelCount(); i++) {
-    chan[i].volMax=(e->getDispatch(e->dispatchOfChan[i])->dispatch(DivCommand(DIV_CMD_GET_VOLMAX,e->dispatchChanOfChan[i]))<<8)|0xff;
+    chan[i].volMax=(e->getDispatch(e->song.dispatchOfChan[i])->dispatch(DivCommand(DIV_CMD_GET_VOLMAX,e->song.dispatchChanOfChan[i]))<<8)|0xff;
     chan[i].volume=chan[i].volMax;
   }
 
diff --git a/src/engine/cmdStreamOps.cpp b/src/engine/cmdStreamOps.cpp
index 4b7718424..295862a65 100644
--- a/src/engine/cmdStreamOps.cpp
+++ b/src/engine/cmdStreamOps.cpp
@@ -1303,7 +1303,7 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
 
   // write header
   w->write("FCS",4);
-  w->writeS(chans);
+  w->writeS(song.chans);
   // flags
   w->writeC((options.longPointers?1:0)|(options.bigEndian?2:0));
   // reserved
@@ -1313,7 +1313,7 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
     w->writeC(0);
   }
   // offsets
-  for (int i=0; i<chans; i++) {
+  for (int i=0; i<song.chans; i++) {
     chanStream[i]=new SafeWriter;
     chanStream[i]->init();
     if (options.longPointers) {
@@ -1323,7 +1323,7 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
     }
   }
   // max stack sizes
-  for (int i=0; i<chans; i++) {
+  for (int i=0; i<song.chans; i++) {
     w->writeC(0);
   }
 
@@ -1338,7 +1338,7 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
 
   // PASS 0: play the song and log channel command streams
   // song beginning marker
-  for (int i=0; i<chans; i++) {
+  for (int i=0; i<song.chans; i++) {
     chanStream[i]->writeC(0xd0);
     chanStream[i]->writeC(i);
     chanStream[i]->writeC(0x00);
@@ -1350,7 +1350,7 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
     chanStream[i]->writeC(0x00);
   }
   while (!done) {
-    for (int i=0; i<chans; i++) {
+    for (int i=0; i<song.chans; i++) {
       tickPos[i].push_back(chanStream[i]->tell());
     }
     if (loopTick==-1) {
@@ -1359,7 +1359,7 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
           logI("loop is on tick %d",tick);
           loopTick=tick;
           // loop marker
-          for (int i=0; i<chans; i++) {
+          for (int i=0; i<song.chans; i++) {
             chanStream[i]->writeC(0xd0);
             chanStream[i]->writeC(i);
             chanStream[i]->writeC(0x00);
@@ -1410,7 +1410,7 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
       }
     }
     cmdStream.clear();
-    for (int i=0; i<chans; i++) {
+    for (int i=0; i<song.chans; i++) {
       chanStream[i]->writeC(0xde);
       // padding
       chanStream[i]->writeC(0x00);
@@ -1424,7 +1424,7 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
     tick++;
   }
   if (!playing || loopTick<0) {
-    for (int i=0; i<chans; i++) {
+    for (int i=0; i<song.chans; i++) {
       chanStream[i]->writeC(0xdf);
       // padding
       chanStream[i]->writeC(0x00);
@@ -1436,7 +1436,7 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
       chanStream[i]->writeC(0x00);
     }
   } else {
-    for (int i=0; i<chans; i++) {
+    for (int i=0; i<song.chans; i++) {
       if ((int)tickPos[i].size()>loopTick) {
         chanStream[i]->writeC(0xda);
         chanStream[i]->writeI(tickPos[i][loopTick]);
@@ -1494,7 +1494,7 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
     }
 
     // set preset instruments
-    for (int h=0; h<chans; h++) {
+    for (int h=0; h<song.chans; h++) {
       unsigned char* buf=chanStream[h]->getFinalBuf();
       for (size_t i=0; i<chanStream[h]->size(); i+=8) {
         if (buf[i]==0xb8) {
@@ -1536,7 +1536,7 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
     }
 
     // set preset volumes
-    for (int h=0; h<chans; h++) {
+    for (int h=0; h<song.chans; h++) {
       unsigned char* buf=chanStream[h]->getFinalBuf();
       for (size_t i=0; i<chanStream[h]->size(); i+=8) {
         if (buf[i]==0xc7) {
@@ -1578,7 +1578,7 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
     }
 
     // set speed dial commands
-    for (int h=0; h<chans; h++) {
+    for (int h=0; h<song.chans; h++) {
       unsigned char* buf=chanStream[h]->getFinalBuf();
       for (size_t i=0; i<chanStream[h]->size(); i+=8) {
         if (buf[i]==0xd7) {
@@ -1601,7 +1601,7 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
   // PASS 2: condense delays
   if (!options.noDelayCondense) {
     // calculate delay usage
-    for (int h=0; h<chans; h++) {
+    for (int h=0; h<song.chans; h++) {
       unsigned char* buf=chanStream[h]->getFinalBuf();
       int delayCount=0;
       for (size_t i=0; i<chanStream[h]->size(); i+=8) {
@@ -1639,7 +1639,7 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
     }
 
     // condense delays
-    for (int h=0; h<chans; h++) {
+    for (int h=0; h<song.chans; h++) {
       unsigned char* buf=chanStream[h]->getFinalBuf();
       int delayPos=-1;
       int delayCount=0;
@@ -1693,7 +1693,7 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
 
   // PASS 3: note off + one-tick wait
   // optimize one-tick gaps sometimes used in songs
-  for (int h=0; h<chans; h++) {
+  for (int h=0; h<song.chans; h++) {
     unsigned char* buf=chanStream[h]->getFinalBuf();
     if (chanStream[h]->size()<8) continue;
     for (size_t i=0; i<chanStream[h]->size()-8; i+=8) {
@@ -1714,12 +1714,12 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
 
   // PASS 4: remove nop's
   // this includes modifying call addresses to compensate
-  for (int h=0; h<chans; h++) {
+  for (int h=0; h<song.chans; h++) {
     chanStream[h]=stripNops(chanStream[h]);
   }
 
   // PASS 5: put all channels together
-  for (int i=0; i<chans; i++) {
+  for (int i=0; i<song.chans; i++) {
     chanStreamOff[i]=globalStream->tell();
     logI("- %d: off %x size %ld",i,chanStreamOff[i],chanStream[i]->size());
     reloc8(chanStream[i]->getFinalBuf(),chanStream[i]->size(),0,globalStream->tell());
@@ -1798,7 +1798,7 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
   // also find new offsets
   globalStream=stripNopsPacked(globalStream,sortedCmd,chanStreamOff);
 
-  for (int h=0; h<chans; h++) {
+  for (int h=0; h<song.chans; h++) {
     chanStreamOff[h]+=w->tell();
   }
 
@@ -1807,7 +1807,7 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
   w->write(globalStream->getFinalBuf(),globalStream->size());
 
   // calculate max stack sizes
-  for (int h=0; h<chans; h++) {
+  for (int h=0; h<song.chans; h++) {
     std::stack<unsigned int> callStack;
     unsigned int maxStackSize=0;
     unsigned char* buf=w->getFinalBuf();
@@ -1866,7 +1866,7 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
   delete globalStream;
 
   w->seek(40,SEEK_SET);
-  for (int i=0; i<chans; i++) {
+  for (int i=0; i<song.chans; i++) {
     if (options.longPointers) {
       if (options.bigEndian) {
         w->writeI_BE(chanStreamOff[i]);
@@ -1884,7 +1884,7 @@ SafeWriter* DivEngine::saveCommand(DivCSProgress* progress, DivCSOptions options
 
   logD("maximum stack sizes:");
   unsigned int cumulativeStackSize=0;
-  for (int i=0; i<chans; i++) {
+  for (int i=0; i<song.chans; i++) {
     w->writeC(chanStackSize[i]);
     logD("- %d: %d",i,chanStackSize[i]);
     cumulativeStackSize+=chanStackSize[i];
diff --git a/src/engine/engine.cpp b/src/engine/engine.cpp
index 5c552290a..1de23a682 100644
--- a/src/engine/engine.cpp
+++ b/src/engine/engine.cpp
@@ -179,19 +179,23 @@ const char* DivEngine::getEffectDesc(unsigned char effect, int chan, bool notNul
           case 0x92:
             return _("92xx: Set sample offset (third byte, ×65536)");
         }
-      } else if (chan>=0 && chan<chans) {
-        DivSysDef* sysDef=sysDefs[sysOfChan[chan]];
-        auto iter=sysDef->effectHandlers.find(effect);
-        if (iter!=sysDef->effectHandlers.end()) {
-          return iter->second.description;
-        }
-        iter=sysDef->postEffectHandlers.find(effect);
-        if (iter!=sysDef->postEffectHandlers.end()) {
-          return iter->second.description;
-        }
-        iter=sysDef->preEffectHandlers.find(effect);
-        if (iter!=sysDef->preEffectHandlers.end()) {
-          return iter->second.description;
+      } else if (chan>=0 && chan<song.chans) {
+        DivSysDef* sysDef=sysDefs[song.sysOfChan[chan]];
+        if (sysDef==NULL) {
+          return notNull?_("Invalid effect"):NULL;
+        } else {
+          auto iter=sysDef->effectHandlers.find(effect);
+          if (iter!=sysDef->effectHandlers.end()) {
+            return iter->second.description;
+          }
+          iter=sysDef->postEffectHandlers.find(effect);
+          if (iter!=sysDef->postEffectHandlers.end()) {
+            return iter->second.description;
+          }
+          iter=sysDef->preEffectHandlers.find(effect);
+          if (iter!=sysDef->preEffectHandlers.end()) {
+            return iter->second.description;
+          }
         }
       }
       break;
@@ -201,7 +205,7 @@ const char* DivEngine::getEffectDesc(unsigned char effect, int chan, bool notNul
 
 void DivEngine::calcSongTimestamps() {
   if (curSubSong!=NULL) {
-    curSubSong->calcTimestamps(chans,song.grooves,song.jumpTreatment,song.ignoreJumpAtEnd,song.brokenSpeedSel,song.delayBehavior);
+    curSubSong->calcTimestamps(song.chans,song.grooves,song.jumpTreatment,song.ignoreJumpAtEnd,song.brokenSpeedSel,song.delayBehavior);
   }
 }
 
@@ -531,6 +535,7 @@ void DivEngine::initSongWithDesc(const char* description, bool inBase64, bool ol
     song.systemFlags[index].loadFromBase64(flags.c_str());
   }
   song.systemLen=index;
+  song.initDefaultSystemChans();
   
   // extra attributes
   song.subsong[0]->hz=c.getDouble("tickRate",60.0);
@@ -564,7 +569,8 @@ void DivEngine::createNew(const char* description, String sysName, bool inBase64
   } else {
     song.systemName=sysName;
   }
-  recalcChans();
+  song.initDefaultSystemChans();
+  song.recalcChans();
   saveLock.unlock();
   BUSY_END;
   initDispatch();
@@ -602,7 +608,8 @@ void DivEngine::createNewFromDefaults() {
     song.systemName=sysName;
   }
 
-  recalcChans();
+  song.initDefaultSystemChans();
+  song.recalcChans();
   saveLock.unlock();
   BUSY_END;
   initDispatch();
@@ -710,8 +717,8 @@ void DivEngine::changeSong(size_t songIndex) {
 }
 
 void DivEngine::copyChannelP(int src, int dest) {
-  if (src<0 || src>=chans) return;
-  if (dest<0 || dest>=chans) return;
+  if (src<0 || src>=song.chans) return;
+  if (dest<0 || dest>=song.chans) return;
   BUSY_BEGIN;
   saveLock.lock();
   copyChannel(src,dest);
@@ -720,8 +727,8 @@ void DivEngine::copyChannelP(int src, int dest) {
 }
 
 void DivEngine::swapChannelsP(int src, int dest) {
-  if (src<0 || src>=chans) return;
-  if (dest<0 || dest>=chans) return;
+  if (src<0 || src>=song.chans) return;
+  if (dest<0 || dest>=song.chans) return;
   BUSY_BEGIN;
   saveLock.lock();
   swapChannels(src,dest);
@@ -874,7 +881,7 @@ void DivEngine::delUnusedIns() {
   memset(isUsed,0,256*sizeof(bool));
 
   // scan
-  for (int i=0; i<chans; i++) {
+  for (int i=0; i<song.chans; i++) {
     for (size_t j=0; j<song.subsong.size(); j++) {
       for (int k=0; k<DIV_MAX_PATTERNS; k++) {
         if (song.subsong[j]->pat[i].data[k]==NULL) continue;
@@ -992,12 +999,12 @@ bool DivEngine::changeSystem(int index, DivSystem which, bool preserveOrder) {
     lastError=_("invalid index");
     return false;
   }
-  if (chans-getChannelCount(song.system[index])+getChannelCount(which)>DIV_MAX_CHANS) {
+  if (song.chans-getChannelCount(song.system[index])+getChannelCount(which)>DIV_MAX_CHANS) {
     lastError=fmt::sprintf(_("max number of total channels is %d"),DIV_MAX_CHANS);
     return false;
   }
 
-  int chanCount=chans;
+  int chanCount=song.chans;
   quitDispatch();
   BUSY_BEGIN;
   saveLock.lock();
@@ -1005,7 +1012,7 @@ bool DivEngine::changeSystem(int index, DivSystem which, bool preserveOrder) {
   if (!preserveOrder) {
     int firstChan=0;
     int chanMovement=getChannelCount(which)-getChannelCount(song.system[index]);
-    while (dispatchOfChan[firstChan]!=index) firstChan++;
+    while (song.dispatchOfChan[firstChan]!=index) firstChan++;
     int lastChan=firstChan+getChannelCount(song.system[index]);
     if (chanMovement!=0) {
       if (chanMovement>0) {
@@ -1030,7 +1037,7 @@ bool DivEngine::changeSystem(int index, DivSystem which, bool preserveOrder) {
 
   song.system[index]=which;
   song.systemFlags[index].clear();
-  recalcChans();
+  song.recalcChans();
   saveLock.unlock();
   BUSY_END;
   initDispatch();
@@ -1047,7 +1054,7 @@ bool DivEngine::addSystem(DivSystem which) {
     lastError=fmt::sprintf(_("max number of systems is %d"),DIV_MAX_CHIPS);
     return false;
   }
-  if (chans+getChannelCount(which)>DIV_MAX_CHANS) {
+  if (song.chans+getChannelCount(which)>DIV_MAX_CHANS) {
     lastError=fmt::sprintf(_("max number of total channels is %d"),DIV_MAX_CHANS);
     return false;
   }
@@ -1059,7 +1066,7 @@ bool DivEngine::addSystem(DivSystem which) {
   song.systemPan[song.systemLen]=0;
   song.systemPanFR[song.systemLen]=0;
   song.systemFlags[song.systemLen++].clear();
-  recalcChans();
+  song.recalcChans();
   saveLock.unlock();
   BUSY_END;
   initDispatch();
@@ -1101,7 +1108,7 @@ bool DivEngine::duplicateSystem(int index, bool pat, bool end) {
     lastError=fmt::sprintf(_("max number of systems is %d"),DIV_MAX_CHIPS);
     return false;
   }
-  if (chans+getChannelCount(song.system[index])>DIV_MAX_CHANS) {
+  if (song.chans+getChannelCount(song.system[index])>DIV_MAX_CHANS) {
     lastError=fmt::sprintf(_("max number of total channels is %d"),DIV_MAX_CHANS);
     return false;
   }
@@ -1113,7 +1120,7 @@ bool DivEngine::duplicateSystem(int index, bool pat, bool end) {
   song.systemPan[song.systemLen]=song.systemPan[index];
   song.systemPanFR[song.systemLen]=song.systemPanFR[index];
   song.systemFlags[song.systemLen++]=song.systemFlags[index];
-  recalcChans();
+  song.recalcChans();
   saveLock.unlock();
   BUSY_END;
   initDispatch();
@@ -1184,7 +1191,7 @@ bool DivEngine::duplicateSystem(int index, bool pat, bool end) {
       swapSystemUnsafe(i,i-1,false);
     }
 
-    recalcChans();
+    song.recalcChans();
     saveLock.unlock();
     BUSY_END;
     initDispatch();
@@ -1206,14 +1213,14 @@ bool DivEngine::removeSystem(int index, bool preserveOrder) {
     lastError=_("invalid index");
     return false;
   }
-  int chanCount=chans;
+  int chanCount=song.chans;
   quitDispatch();
   BUSY_BEGIN;
   saveLock.lock();
 
   if (!preserveOrder) {
     int firstChan=0;
-    while (dispatchOfChan[firstChan]!=index) firstChan++;
+    while (song.dispatchOfChan[firstChan]!=index) firstChan++;
     for (int i=0; i<getChannelCount(song.system[index]); i++) {
       stompChannel(i+firstChan);
     }
@@ -1239,7 +1246,7 @@ bool DivEngine::removeSystem(int index, bool preserveOrder) {
     song.systemPanFR[i]=song.systemPanFR[i+1];
     song.systemFlags[i]=song.systemFlags[i+1];
   }
-  recalcChans();
+  song.recalcChans();
   saveLock.unlock();
   BUSY_END;
   initDispatch();
@@ -1391,7 +1398,7 @@ bool DivEngine::swapSystem(int src, int dest, bool preserveOrder) {
 
   swapSystemUnsafe(src,dest,preserveOrder);
 
-  recalcChans();
+  song.recalcChans();
   saveLock.unlock();
   BUSY_END;
   initDispatch();
@@ -1514,28 +1521,28 @@ void DivEngine::setLoops(int loops) {
 }
 
 DivChannelState* DivEngine::getChanState(int ch) {
-  if (ch<0 || ch>=chans) return NULL;
+  if (ch<0 || ch>=song.chans) return NULL;
   return &chan[ch];
 }
 
 unsigned short DivEngine::getChanPan(int ch) {
-  if (ch<0 || ch>=chans) return 0;
-  return disCont[dispatchOfChan[ch]].dispatch->getPan(dispatchChanOfChan[ch]);
+  if (ch<0 || ch>=song.chans) return 0;
+  return disCont[song.dispatchOfChan[ch]].dispatch->getPan(song.dispatchChanOfChan[ch]);
 }
 
 void* DivEngine::getDispatchChanState(int ch) {
-  if (ch<0 || ch>=chans) return NULL;
-  return disCont[dispatchOfChan[ch]].dispatch->getChanState(dispatchChanOfChan[ch]);
+  if (ch<0 || ch>=song.chans) return NULL;
+  return disCont[song.dispatchOfChan[ch]].dispatch->getChanState(song.dispatchChanOfChan[ch]);
 }
 
 void DivEngine::getChanPaired(int ch, std::vector<DivChannelPair>& ret) {
-  if (ch<0 || ch>=chans) return;
-  disCont[dispatchOfChan[ch]].dispatch->getPaired(dispatchChanOfChan[ch],ret);
+  if (ch<0 || ch>=song.chans) return;
+  disCont[song.dispatchOfChan[ch]].dispatch->getPaired(song.dispatchChanOfChan[ch],ret);
 }
 
 DivChannelModeHints DivEngine::getChanModeHints(int ch) {
-  if (ch<0 || ch>=chans) return DivChannelModeHints();
-  return disCont[dispatchOfChan[ch]].dispatch->getModeHints(dispatchChanOfChan[ch]);
+  if (ch<0 || ch>=song.chans) return DivChannelModeHints();
+  return disCont[song.dispatchOfChan[ch]].dispatch->getModeHints(song.dispatchChanOfChan[ch]);
 }
 
 unsigned char* DivEngine::getRegisterPool(int sys, int& size, int& depth) {
@@ -1547,18 +1554,18 @@ unsigned char* DivEngine::getRegisterPool(int sys, int& size, int& depth) {
 }
 
 DivMacroInt* DivEngine::getMacroInt(int chan) {
-  if (chan<0 || chan>=chans) return NULL;
-  return disCont[dispatchOfChan[chan]].dispatch->getChanMacroInt(dispatchChanOfChan[chan]);
+  if (chan<0 || chan>=song.chans) return NULL;
+  return disCont[song.dispatchOfChan[chan]].dispatch->getChanMacroInt(song.dispatchChanOfChan[chan]);
 }
 
 DivSamplePos DivEngine::getSamplePos(int chan) {
-  if (chan<0 || chan>=chans) return DivSamplePos();
-  return disCont[dispatchOfChan[chan]].dispatch->getSamplePos(dispatchChanOfChan[chan]);
+  if (chan<0 || chan>=song.chans) return DivSamplePos();
+  return disCont[song.dispatchOfChan[chan]].dispatch->getSamplePos(song.dispatchChanOfChan[chan]);
 }
 
 DivDispatchOscBuffer* DivEngine::getOscBuffer(int chan) {
-  if (chan<0 || chan>=chans) return NULL;
-  return disCont[dispatchOfChan[chan]].dispatch->getOscBuffer(dispatchChanOfChan[chan]);
+  if (chan<0 || chan>=song.chans) return NULL;
+  return disCont[song.dispatchOfChan[chan]].dispatch->getOscBuffer(song.dispatchChanOfChan[chan]);
 }
 
 void DivEngine::enableCommandStream(bool enable) {
@@ -1694,7 +1701,7 @@ void DivEngine::playSub(bool preserveDrift, int goalRow) {
   if (goal>0 || goalRow>0) {
     for (int i=0; i<song.systemLen; i++) disCont[i].dispatch->forceIns();
   }
-  for (int i=0; i<chans; i++) {
+  for (int i=0; i<song.chans; i++) {
     chan[i].cut=-1;
     chan[i].cutType=0;
   }
@@ -2041,7 +2048,7 @@ void DivEngine::stop() {
   }
   if (output) if (output->midiOut!=NULL) {
     output->midiOut->send(TAMidiMessage(TA_MIDI_MACHINE_STOP,0,0));
-    for (int i=0; i<chans; i++) {
+    for (int i=0; i<song.chans; i++) {
       if (chan[i].curMidiNote>=0) {
         output->midiOut->send(TAMidiMessage(0x80|(i&15),chan[i].curMidiNote,0));
       }
@@ -2053,8 +2060,8 @@ void DivEngine::stop() {
   }
 
   // reset all chan oscs
-  for (int i=0; i<chans; i++) {
-    DivDispatchOscBuffer* buf=disCont[dispatchOfChan[i]].dispatch->getOscBuffer(dispatchChanOfChan[i]);
+  for (int i=0; i<song.chans; i++) {
+    DivDispatchOscBuffer* buf=disCont[song.dispatchOfChan[i]].dispatch->getOscBuffer(song.dispatchChanOfChan[i]);
     if (buf!=NULL) {
       buf->reset();
     }
@@ -2094,7 +2101,7 @@ const char** DivEngine::getRegisterSheet(int sys) {
 void DivEngine::reset() {
   if (output) if (output->midiOut!=NULL) {
     output->midiOut->send(TAMidiMessage(TA_MIDI_MACHINE_STOP,0,0));
-    for (int i=0; i<chans; i++) {
+    for (int i=0; i<song.chans; i++) {
       if (chan[i].curMidiNote>=0) {
         output->midiOut->send(TAMidiMessage(0x80|(i&15),chan[i].curMidiNote,0));
       }
@@ -2102,7 +2109,7 @@ void DivEngine::reset() {
   }
   for (int i=0; i<DIV_MAX_CHANS; i++) {
     chan[i]=DivChannelState();
-    if (i<chans) chan[i].volMax=(disCont[dispatchOfChan[i]].dispatch->dispatch(DivCommand(DIV_CMD_GET_VOLMAX,dispatchChanOfChan[i]))<<8)|0xff;
+    if (i<song.chans) chan[i].volMax=(disCont[song.dispatchOfChan[i]].dispatch->dispatch(DivCommand(DIV_CMD_GET_VOLMAX,song.dispatchChanOfChan[i]))<<8)|0xff;
     chan[i].volume=chan[i].volMax;
     if (!song.linearPitch) chan[i].vibratoFine=4;
   }
@@ -2375,16 +2382,16 @@ int DivEngine::getMaxVolumeChan(int ch) {
 
 int DivEngine::mapVelocity(int ch, float vel) {
   if (ch<0) return 0;
-  if (ch>=chans) return 0;
-  if (disCont[dispatchOfChan[ch]].dispatch==NULL) return 0;
-  return disCont[dispatchOfChan[ch]].dispatch->mapVelocity(dispatchChanOfChan[ch],vel);
+  if (ch>=song.chans) return 0;
+  if (disCont[song.dispatchOfChan[ch]].dispatch==NULL) return 0;
+  return disCont[song.dispatchOfChan[ch]].dispatch->mapVelocity(song.dispatchChanOfChan[ch],vel);
 }
 
 float DivEngine::getGain(int ch, int vol) {
   if (ch<0) return 0;
-  if (ch>=chans) return 0;
-  if (disCont[dispatchOfChan[ch]].dispatch==NULL) return 0;
-  return disCont[dispatchOfChan[ch]].dispatch->getGain(dispatchChanOfChan[ch],vol);
+  if (ch>=song.chans) return 0;
+  if (disCont[song.dispatchOfChan[ch]].dispatch==NULL) return 0;
+  return disCont[song.dispatchOfChan[ch]].dispatch->getGain(song.dispatchChanOfChan[ch],vol);
 }
 
 unsigned char DivEngine::getOrder() {
@@ -2494,7 +2501,7 @@ void DivEngine::toggleMute(int chan) {
 
 void DivEngine::toggleSolo(int chan) {
   bool solo=false;
-  for (int i=0; i<chans; i++) {
+  for (int i=0; i<song.chans; i++) {
     if (i==chan) {
       solo=true;
       continue;
@@ -2507,17 +2514,17 @@ void DivEngine::toggleSolo(int chan) {
   }
   BUSY_BEGIN;
   if (!solo) {
-    for (int i=0; i<chans; i++) {
+    for (int i=0; i<song.chans; i++) {
       isMuted[i]=(i!=chan);
-      if (disCont[dispatchOfChan[i]].dispatch!=NULL) {
-        disCont[dispatchOfChan[i]].dispatch->muteChannel(dispatchChanOfChan[i],isMuted[i]);
+      if (disCont[song.dispatchOfChan[i]].dispatch!=NULL) {
+        disCont[song.dispatchOfChan[i]].dispatch->muteChannel(song.dispatchChanOfChan[i],isMuted[i]);
       }
     }
   } else {
-    for (int i=0; i<chans; i++) {
+    for (int i=0; i<song.chans; i++) {
       isMuted[i]=false;
-      if (disCont[dispatchOfChan[i]].dispatch!=NULL) {
-        disCont[dispatchOfChan[i]].dispatch->muteChannel(dispatchChanOfChan[i],isMuted[i]);
+      if (disCont[song.dispatchOfChan[i]].dispatch!=NULL) {
+        disCont[song.dispatchOfChan[i]].dispatch->muteChannel(song.dispatchChanOfChan[i],isMuted[i]);
       }
     }
   }
@@ -2527,18 +2534,18 @@ void DivEngine::toggleSolo(int chan) {
 void DivEngine::muteChannel(int chan, bool mute) {
   BUSY_BEGIN;
   isMuted[chan]=mute;
-  if (disCont[dispatchOfChan[chan]].dispatch!=NULL) {
-    disCont[dispatchOfChan[chan]].dispatch->muteChannel(dispatchChanOfChan[chan],isMuted[chan]);
+  if (disCont[song.dispatchOfChan[chan]].dispatch!=NULL) {
+    disCont[song.dispatchOfChan[chan]].dispatch->muteChannel(song.dispatchChanOfChan[chan],isMuted[chan]);
   }
   BUSY_END;
 }
 
 void DivEngine::unmuteAll() {
   BUSY_BEGIN;
-  for (int i=0; i<chans; i++) {
+  for (int i=0; i<song.chans; i++) {
     isMuted[i]=false;
-    if (disCont[dispatchOfChan[i]].dispatch!=NULL) {
-      disCont[dispatchOfChan[i]].dispatch->muteChannel(dispatchChanOfChan[i],isMuted[i]);
+    if (disCont[song.dispatchOfChan[i]].dispatch!=NULL) {
+      disCont[song.dispatchOfChan[i]].dispatch->muteChannel(song.dispatchChanOfChan[i],isMuted[i]);
     }
   }
   BUSY_END;
@@ -2609,8 +2616,8 @@ int DivEngine::addInstrument(int refChan, DivInstrumentType fallbackType) {
   DivInstrument* ins=new DivInstrument;
   int insCount=(int)song.ins.size();
   DivInstrumentType prefType;
-  if (refChan>chans) {
-    refChan=chans-1;
+  if (refChan>song.chans) {
+    refChan=song.chans-1;
   }
   if (refChan<0) {
     prefType=fallbackType;
@@ -2634,7 +2641,7 @@ int DivEngine::addInstrument(int refChan, DivInstrumentType fallbackType) {
       break;
   }
   if (refChan>=0) {
-    if (sysOfChan[refChan]==DIV_SYSTEM_QSOUND) {
+    if (song.sysOfChan[refChan]==DIV_SYSTEM_QSOUND) {
       *ins=song.nullInsQSound;
     }
   }
@@ -2694,7 +2701,7 @@ void DivEngine::delInstrumentUnsafe(int index) {
     delete song.ins[index];
     song.ins.erase(song.ins.begin()+index);
     song.insLen=song.ins.size();
-    for (int i=0; i<chans; i++) {
+    for (int i=0; i<song.chans; i++) {
       for (size_t j=0; j<song.subsong.size(); j++) {
         for (int k=0; k<DIV_MAX_PATTERNS; k++) {
           if (song.subsong[j]->pat[i].data[k]==NULL) continue;
@@ -3004,7 +3011,7 @@ void DivEngine::addOrder(int pos, bool duplicate, bool where) {
     }
   } else {
     bool used[DIV_MAX_PATTERNS];
-    for (int i=0; i<chans; i++) {
+    for (int i=0; i<song.chans; i++) {
       memset(used,0,sizeof(bool)*DIV_MAX_PATTERNS);
       for (int j=0; j<curSubSong->ordersLen; j++) {
         used[curOrders->ord[i][j]]=true;
@@ -3053,7 +3060,7 @@ void DivEngine::deepCloneOrder(int pos, bool where) {
   if (curSubSong->ordersLen>=(DIV_MAX_PATTERNS-1)) return;
   warnings="";
   BUSY_BEGIN_SOFT;
-  for (int i=0; i<chans; i++) {
+  for (int i=0; i<song.chans; i++) {
     bool didNotFind=true;
     logD("channel %d",i);
     order[i]=curOrders->ord[i][pos];
@@ -3077,14 +3084,14 @@ void DivEngine::deepCloneOrder(int pos, bool where) {
   }
   if (where) { // at the end
     saveLock.lock();
-    for (int i=0; i<chans; i++) {
+    for (int i=0; i<song.chans; i++) {
       curOrders->ord[i][curSubSong->ordersLen]=order[i];
     }
     curSubSong->ordersLen++;
     saveLock.unlock();
   } else { // after current order
     saveLock.lock();
-    for (int i=0; i<chans; i++) {
+    for (int i=0; i<song.chans; i++) {
       for (int j=curSubSong->ordersLen; j>pos; j--) {
         curOrders->ord[i][j]=curOrders->ord[i][j-1];
       }
@@ -3182,7 +3189,7 @@ void DivEngine::moveOrderDown(int& pos) {
 }
 
 void DivEngine::exchangeIns(int one, int two) {
-  for (int i=0; i<chans; i++) {
+  for (int i=0; i<song.chans; i++) {
     for (size_t j=0; j<song.subsong.size(); j++) {
       for (int k=0; k<DIV_MAX_PATTERNS; k++) {
         if (song.subsong[j]->pat[i].data[k]==NULL) continue;
@@ -3468,7 +3475,7 @@ void DivEngine::patchDisconnectAll(unsigned int portSet) {
 }
 
 void DivEngine::noteOn(int chan, int ins, int note, int vol) {
-  if (chan<0 || chan>=chans) return;
+  if (chan<0 || chan>=song.chans) return;
   BUSY_BEGIN;
   pendingNotes.push_back(DivNoteEvent(chan,ins,note,vol,true));
   if (!playing) {
@@ -3480,7 +3487,7 @@ void DivEngine::noteOn(int chan, int ins, int note, int vol) {
 }
 
 void DivEngine::noteOff(int chan) {
-  if (chan<0 || chan>=chans) return;
+  if (chan<0 || chan>=song.chans) return;
   BUSY_BEGIN;
   pendingNotes.push_back(DivNoteEvent(chan,-1,-1,-1,false));
   if (!playing) {
@@ -3497,7 +3504,7 @@ int DivEngine::getViableChannel(int chan, int off, int ins) {
 
   // if there isn't an instrument, just offset chan by off
   if (ins==-1) {
-    return (chan+off)%chans;
+    return (chan+off)%song.chans;
   }
   
   bool isViable[DIV_MAX_CHANS];
@@ -3507,7 +3514,7 @@ int DivEngine::getViableChannel(int chan, int off, int ins) {
 
   // this is a copy of the routine in autoNoteOn...... I am lazy
   DivInstrument* insInst=getIns(ins);
-  for (int i=0; i<chans; i++) {
+  for (int i=0; i<song.chans; i++) {
     if (ins==-1 || ins>=song.insLen || getPreferInsType(i)==insInst->type || (getPreferInsType(i)==DIV_INS_NULL && finalChanType==DIV_CH_NOISE) || getPreferInsSecondType(i)==insInst->type) {
       if (insInst->type==DIV_INS_OPL) {
         if (insInst->fm.ops==2 || getChannelType(i)==DIV_CH_OP) {
@@ -3527,12 +3534,12 @@ int DivEngine::getViableChannel(int chan, int off, int ins) {
 
   // screw it if none of the channels are viable
   if (!isAtLeastOneViable) {
-    return (chan+off)%chans;
+    return (chan+off)%song.chans;
   }
 
   // now offset (confined to viable channels)
   int channelsCycled=0;
-  int i=(chan+1)%chans;
+  int i=(chan+1)%song.chans;
   int attempts=0;
   while (true) {
     if (isViable[i]) {
@@ -3543,7 +3550,7 @@ int DivEngine::getViableChannel(int chan, int off, int ins) {
       }
     }
 
-    if (++i>=chans) {
+    if (++i>=song.chans) {
       i=0;
     }
 
@@ -3555,7 +3562,7 @@ int DivEngine::getViableChannel(int chan, int off, int ins) {
   }
 
   // fail-safe
-  return (chan+off)%chans;
+  return (chan+off)%song.chans;
 }
 
 bool DivEngine::autoNoteOn(int ch, int ins, int note, int vol, int transpose) {
@@ -3563,7 +3570,7 @@ bool DivEngine::autoNoteOn(int ch, int ins, int note, int vol, int transpose) {
   bool canPlayAnyway=false;
   bool notInViableChannel=false;
   if (midiBaseChan<0) midiBaseChan=0;
-  if (midiBaseChan>=chans) midiBaseChan=chans-1;
+  if (midiBaseChan>=song.chans) midiBaseChan=song.chans-1;
   int finalChan=midiBaseChan;
   int finalChanType=getChannelType(finalChan);
 
@@ -3576,7 +3583,7 @@ bool DivEngine::autoNoteOn(int ch, int ins, int note, int vol, int transpose) {
   // 1. check which channels are viable for this instrument
   DivInstrument* insInst=getIns(ins);
   if (getPreferInsType(finalChan)!=insInst->type && getPreferInsSecondType(finalChan)!=insInst->type && getPreferInsType(finalChan)!=DIV_INS_NULL) notInViableChannel=true;
-  for (int i=0; i<chans; i++) {
+  for (int i=0; i<song.chans; i++) {
     if (ins==-1 || ins>=song.insLen || getPreferInsType(i)==insInst->type || (getPreferInsType(i)==DIV_INS_NULL && finalChanType==DIV_CH_NOISE) || getPreferInsSecondType(i)==insInst->type) {
       if (insInst->type==DIV_INS_OPL) {
         if (insInst->fm.ops==2 || getChannelType(i)==DIV_CH_OP) {
@@ -3604,7 +3611,7 @@ bool DivEngine::autoNoteOn(int ch, int ins, int note, int vol, int transpose) {
       pendingNotes.push_back(DivNoteEvent(finalChan,ins,note+transpose,vol,true));
       return true;
     }
-    if (++finalChan>=chans) {
+    if (++finalChan>=song.chans) {
       finalChan=0;
     }
   } while (finalChan!=midiBaseChan);
@@ -3615,7 +3622,7 @@ bool DivEngine::autoNoteOn(int ch, int ins, int note, int vol, int transpose) {
     if (isViable[finalChan] && (insInst->type==DIV_INS_OPL || getChannelType(finalChan)==finalChanType || notInViableChannel) && chan[finalChan].midiAge<chan[candidate].midiAge) {
       candidate=finalChan;
     }
-    if (++finalChan>=chans) {
+    if (++finalChan>=song.chans) {
       finalChan=0;
     }
   } while (finalChan!=midiBaseChan);
@@ -3630,8 +3637,8 @@ void DivEngine::autoNoteOff(int ch, int note, int vol) {
   if (!playing) {
     return;
   }
-  //if (ch<0 || ch>=chans) return;
-  for (int i=0; i<chans; i++) {
+  //if (ch<0 || ch>=song.chans) return;
+  for (int i=0; i<song.chans; i++) {
     if (chan[i].midiNote==note) {
       pendingNotes.push_back(DivNoteEvent(i,-1,-1,-1,false));
       chan[i].midiNote=-1;
@@ -3643,7 +3650,7 @@ void DivEngine::autoNoteOffAll() {
   if (!playing) {
     return;
   }
-  for (int i=0; i<chans; i++) {
+  for (int i=0; i<song.chans; i++) {
     if (chan[i].midiNote!=-1) {
       pendingNotes.push_back(DivNoteEvent(i,-1,-1,-1,false));
       chan[i].midiNote=-1;
@@ -3768,7 +3775,7 @@ bool DivEngine::switchMaster(bool full) {
 }
 
 void DivEngine::setMidiBaseChan(int chan) {
-  if (chan<0 || chan>=chans) chan=0;
+  if (chan<0 || chan>=song.chans) chan=0;
   midiBaseChan=chan;
 }
 
@@ -3912,7 +3919,7 @@ void DivEngine::initDispatch(bool isRender) {
     autoPatchbay();
     saveLock.unlock();
   }
-  recalcChans();
+  song.recalcChans();
   BUSY_END;
 }
 
@@ -3928,7 +3935,6 @@ void DivEngine::quitDispatch() {
   midiClockDrift=0;
   midiTimeCycles=0;
   midiTimeDrift=0;
-  chans=0;
   playing=false;
   curSpeed=0;
   endOfSong=false;
diff --git a/src/engine/export/amigaValidation.cpp b/src/engine/export/amigaValidation.cpp
index 30224e84f..38b61a41f 100644
--- a/src/engine/export/amigaValidation.cpp
+++ b/src/engine/export/amigaValidation.cpp
@@ -91,7 +91,7 @@ void DivExportAmigaValidation::run() {
   size_t lastTick=0;
   //bool writeLoop=false;
   int loopPos=-1;
-  for (int i=0; i<e->chans; i++) {
+  for (int i=0; i<e->song.chans; i++) {
     e->chan[i].wentThroughNote=false;
     e->chan[i].goneThroughNote=false;
   }
diff --git a/src/engine/fileOps/dmf.cpp b/src/engine/fileOps/dmf.cpp
index 492f0c21f..2557e4b6d 100644
--- a/src/engine/fileOps/dmf.cpp
+++ b/src/engine/fileOps/dmf.cpp
@@ -1168,6 +1168,7 @@ bool DivEngine::loadDMF(unsigned char* file, size_t len) {
     }
 
     ds.systemName=getSongSystemLegacyName(ds,!getConfInt("noMultiSystem",0));
+    ds.initDefaultSystemChans();
     ds.recalcChans();
 
     if (active) quitDispatch();
@@ -1175,6 +1176,7 @@ bool DivEngine::loadDMF(unsigned char* file, size_t len) {
     saveLock.lock();
     song.unload();
     song=ds;
+    hasLoadedSomething=true;
     changeSong(0);
     // always convert to normal sample mode (I have no idea how will I do export)
     convertLegacySampleMode();
diff --git a/src/engine/fileOps/fc.cpp b/src/engine/fileOps/fc.cpp
index 8fbf49502..027dda971 100644
--- a/src/engine/fileOps/fc.cpp
+++ b/src/engine/fileOps/fc.cpp
@@ -664,6 +664,7 @@ bool DivEngine::loadFC(unsigned char* file, size_t len) {
     ds.subsong[0]->optimizePatterns();
     ds.subsong[0]->rearrangePatterns();
 
+    ds.initDefaultSystemChans();
     ds.recalcChans();
 
     if (active) quitDispatch();
@@ -671,8 +672,8 @@ bool DivEngine::loadFC(unsigned char* file, size_t len) {
     saveLock.lock();
     song.unload();
     song=ds;
+    hasLoadedSomething=true;
     changeSong(0);
-    recalcChans();
     saveLock.unlock();
     BUSY_END;
     if (active) {
diff --git a/src/engine/fileOps/ftm.cpp b/src/engine/fileOps/ftm.cpp
index 1fee6f053..b2df53798 100644
--- a/src/engine/fileOps/ftm.cpp
+++ b/src/engine/fileOps/ftm.cpp
@@ -2802,6 +2802,7 @@ bool DivEngine::loadFTM(unsigned char* file, size_t len, bool dnft, bool dnft_si
       }
     }
 
+    ds.initDefaultSystemChans();
     ds.recalcChans();
 
     if (active) quitDispatch();
@@ -2809,6 +2810,7 @@ bool DivEngine::loadFTM(unsigned char* file, size_t len, bool dnft, bool dnft_si
     saveLock.lock();
     song.unload();
     song=ds;
+    hasLoadedSomething=true;
     changeSong(0);
     saveLock.unlock();
     BUSY_END;
diff --git a/src/engine/fileOps/fur.cpp b/src/engine/fileOps/fur.cpp
index 7a22eed00..6436ba98a 100644
--- a/src/engine/fileOps/fur.cpp
+++ b/src/engine/fileOps/fur.cpp
@@ -2136,6 +2136,7 @@ bool DivEngine::loadFur(unsigned char* file, size_t len, int variantID) {
     saveLock.lock();
     song.unload();
     song=ds;
+    hasLoadedSomething=true;
     changeSong(0);
     // removal of legacy sample mode
     if (song.version<239) {
diff --git a/src/engine/fileOps/it.cpp b/src/engine/fileOps/it.cpp
index 3fe6285a1..3ea6c2bfc 100644
--- a/src/engine/fileOps/it.cpp
+++ b/src/engine/fileOps/it.cpp
@@ -1675,6 +1675,7 @@ bool DivEngine::loadIT(unsigned char* file, size_t len) {
     ds.systemName="PC";
 
     // find subsongs
+    ds.initDefaultSystemChans();
     ds.recalcChans();
     ds.findSubSongs();
 
@@ -1708,6 +1709,7 @@ bool DivEngine::loadIT(unsigned char* file, size_t len) {
     saveLock.lock();
     song.unload();
     song=ds;
+    hasLoadedSomething=true;
     changeSong(0);
     saveLock.unlock();
     BUSY_END;
diff --git a/src/engine/fileOps/mod.cpp b/src/engine/fileOps/mod.cpp
index 7f933b27f..774a0004b 100644
--- a/src/engine/fileOps/mod.cpp
+++ b/src/engine/fileOps/mod.cpp
@@ -431,6 +431,7 @@ bool DivEngine::loadMod(unsigned char* file, size_t len) {
     ds.insLen=ds.ins.size();
 
     // find subsongs
+    ds.initDefaultSystemChans();
     ds.recalcChans();
     ds.findSubSongs();
     
@@ -439,6 +440,7 @@ bool DivEngine::loadMod(unsigned char* file, size_t len) {
     saveLock.lock();
     song.unload();
     song=ds;
+    hasLoadedSomething=true;
     changeSong(0);
     saveLock.unlock();
     BUSY_END;
diff --git a/src/engine/fileOps/s3m.cpp b/src/engine/fileOps/s3m.cpp
index b866b2920..3c03ad2d9 100644
--- a/src/engine/fileOps/s3m.cpp
+++ b/src/engine/fileOps/s3m.cpp
@@ -1179,6 +1179,7 @@ bool DivEngine::loadS3M(unsigned char* file, size_t len) {
     }
 
     // find subsongs
+    ds.initDefaultSystemChans();
     ds.recalcChans();
     ds.findSubSongs();
 
@@ -1215,6 +1216,7 @@ bool DivEngine::loadS3M(unsigned char* file, size_t len) {
     saveLock.lock();
     song.unload();
     song=ds;
+    hasLoadedSomething=true;
     changeSong(0);
     saveLock.unlock();
     BUSY_END;
diff --git a/src/engine/fileOps/text.cpp b/src/engine/fileOps/text.cpp
index 3dbc598d3..bab5dc7ea 100644
--- a/src/engine/fileOps/text.cpp
+++ b/src/engine/fileOps/text.cpp
@@ -302,7 +302,7 @@ SafeWriter* DivEngine::saveText(bool separatePatterns) {
 
     for (int j=0; j<s->ordersLen; j++) {
       w->writeText(fmt::sprintf("%.2X |",j));
-      for (int k=0; k<chans; k++) {
+      for (int k=0; k<song.chans; k++) {
         w->writeText(fmt::sprintf(" %.2X",s->orders.ord[k][j]));
       }
       w->writeText("\n");
@@ -318,7 +318,7 @@ SafeWriter* DivEngine::saveText(bool separatePatterns) {
         for (int k=0; k<s->patLen; k++) {
           w->writeText(fmt::sprintf("%.2X ",k));
 
-          for (int l=0; l<chans; l++) {
+          for (int l=0; l<song.chans; l++) {
             DivPattern* p=s->pat[l].getPattern(s->orders.ord[l][j],false);
             short note, octave;
             noteToSplitNote(p->newData[k][DIV_PAT_NOTE],note,octave);
diff --git a/src/engine/fileOps/tfm.cpp b/src/engine/fileOps/tfm.cpp
index 557ad351b..7ea370f1d 100644
--- a/src/engine/fileOps/tfm.cpp
+++ b/src/engine/fileOps/tfm.cpp
@@ -711,6 +711,7 @@ bool DivEngine::loadTFMv1(unsigned char* file, size_t len) {
     saveLock.lock();
     song.unload();
     song=ds;
+    hasLoadedSomething=true;
     changeSong(0);
     saveLock.unlock();
     BUSY_END;
@@ -905,6 +906,7 @@ bool DivEngine::loadTFMv2(unsigned char* file, size_t len) {
     info.loopPos=loopPos;
     TFMParsePattern(info);
 
+    ds.initDefaultSystemChans();
     ds.recalcChans();
 
     if (active) quitDispatch();
@@ -912,6 +914,7 @@ bool DivEngine::loadTFMv2(unsigned char* file, size_t len) {
     saveLock.lock();
     song.unload();
     song=ds;
+    hasLoadedSomething=true;
     changeSong(0);
     saveLock.unlock();
     BUSY_END;
diff --git a/src/engine/fileOps/xm.cpp b/src/engine/fileOps/xm.cpp
index fe0ec35c1..57e59ab3a 100644
--- a/src/engine/fileOps/xm.cpp
+++ b/src/engine/fileOps/xm.cpp
@@ -1377,6 +1377,7 @@ bool DivEngine::loadXM(unsigned char* file, size_t len) {
     }
 
     // find subsongs
+    ds.initDefaultSystemChans();
     ds.recalcChans();
     ds.findSubSongs();
 
@@ -1385,6 +1386,7 @@ bool DivEngine::loadXM(unsigned char* file, size_t len) {
     saveLock.lock();
     song.unload();
     song=ds;
+    hasLoadedSomething=true;
     changeSong(0);
     saveLock.unlock();
     BUSY_END;
diff --git a/src/engine/legacySample.cpp b/src/engine/legacySample.cpp
index 21734c903..db827adda 100644
--- a/src/engine/legacySample.cpp
+++ b/src/engine/legacySample.cpp
@@ -22,6 +22,7 @@
 #include "engine.h"
 #include <fmt/printf.h>
 
+// TODO: this function could be in DivSong instead
 bool DivEngine::convertLegacySampleMode() {
   logD("converting legacy sample mode...");
   int legacyInsInit=-1;
@@ -114,7 +115,7 @@ bool DivEngine::convertLegacySampleMode() {
   };
 
   for (DivSubSong* h: song.subsong) {
-    for (int i=0; i<chans; i++) {
+    for (int i=0; i<song.chans; i++) {
       // 0: sample off
       // 1: legacy mode
       // 2: normal mode
@@ -125,11 +126,11 @@ bool DivEngine::convertLegacySampleMode() {
       bool noteOffDisablesSampleMode=false;
       bool hasLegacyToggle=false;
 
-      switch (sysOfChan[i]) {
+      switch (song.sysOfChan[i]) {
         case DIV_SYSTEM_NES:
         case DIV_SYSTEM_5E01:
           // NES PCM channel (on by default)
-          if (dispatchChanOfChan[i]!=4) {
+          if (song.dispatchChanOfChan[i]!=4) {
             continue;
           }
           sampleMode=1;
@@ -137,14 +138,14 @@ bool DivEngine::convertLegacySampleMode() {
           break;
         case DIV_SYSTEM_MMC5:
           // MMC5 PCM channel
-          if (dispatchChanOfChan[i]!=2) {
+          if (song.dispatchChanOfChan[i]!=2) {
             continue;
           }
           sampleMode=1;
           break;
         case DIV_SYSTEM_YM2612:
           // YM2612 DAC channel
-          if (dispatchChanOfChan[i]!=5) {
+          if (song.dispatchChanOfChan[i]!=5) {
             continue;
           }
           hasLegacyToggle=true;
@@ -152,7 +153,7 @@ bool DivEngine::convertLegacySampleMode() {
         case DIV_SYSTEM_YM2612_EXT:
         case DIV_SYSTEM_YM2612_CSM:
           // YM2612 DAC channel
-          if (dispatchChanOfChan[i]!=8) {
+          if (song.dispatchChanOfChan[i]!=8) {
             continue;
           }
           hasLegacyToggle=true;
@@ -170,7 +171,7 @@ bool DivEngine::convertLegacySampleMode() {
         case DIV_SYSTEM_YM2610:
         case DIV_SYSTEM_YM2610_FULL:
           // Neo Geo CD ADPCM channels
-          if (dispatchChanOfChan[i]<7) {
+          if (song.dispatchChanOfChan[i]<7) {
             continue;
           }
           sampleMode=1;
@@ -180,7 +181,7 @@ bool DivEngine::convertLegacySampleMode() {
         case DIV_SYSTEM_YM2610_EXT:
         case DIV_SYSTEM_YM2610_FULL_EXT:
           // Neo Geo CD ADPCM channels
-          if (dispatchChanOfChan[i]<10) {
+          if (song.dispatchChanOfChan[i]<10) {
             continue;
           }
           sampleMode=1;
@@ -189,7 +190,7 @@ bool DivEngine::convertLegacySampleMode() {
           break;
         case DIV_SYSTEM_YM2612_DUALPCM:
           // DualPCM DAC
-          if (dispatchChanOfChan[i]<5) {
+          if (song.dispatchChanOfChan[i]<5) {
             continue;
           }
           sampleMode=1;
@@ -197,7 +198,7 @@ bool DivEngine::convertLegacySampleMode() {
           break;
         case DIV_SYSTEM_YM2612_DUALPCM_EXT:
           // DualPCM DAC
-          if (dispatchChanOfChan[i]<8 || dispatchChanOfChan[i]>9) {
+          if (song.dispatchChanOfChan[i]<8 || song.dispatchChanOfChan[i]>9) {
             continue;
           }
           sampleMode=1;
@@ -205,7 +206,7 @@ bool DivEngine::convertLegacySampleMode() {
           break;
         case DIV_SYSTEM_YM2610_CSM:
           // Neo Geo CD ADPCM channels
-          if (dispatchChanOfChan[i]<11) {
+          if (song.dispatchChanOfChan[i]<11) {
             continue;
           }
           sampleMode=1;
@@ -214,7 +215,7 @@ bool DivEngine::convertLegacySampleMode() {
           break;
         case DIV_SYSTEM_YM2610B:
           // ADPCM channels
-          if (dispatchChanOfChan[i]<9) {
+          if (song.dispatchChanOfChan[i]<9) {
             continue;
           }
           sampleMode=1;
@@ -223,7 +224,7 @@ bool DivEngine::convertLegacySampleMode() {
           break;
         case DIV_SYSTEM_YM2610B_EXT:
           // ADPCM channels
-          if (dispatchChanOfChan[i]<12) {
+          if (song.dispatchChanOfChan[i]<12) {
             continue;
           }
           sampleMode=1;
@@ -232,7 +233,7 @@ bool DivEngine::convertLegacySampleMode() {
           break;
         case DIV_SYSTEM_YM2610B_CSM:
           // ADPCM channels
-          if (dispatchChanOfChan[i]<13) {
+          if (song.dispatchChanOfChan[i]<13) {
             continue;
           }
           sampleMode=1;
@@ -241,7 +242,7 @@ bool DivEngine::convertLegacySampleMode() {
           break;
         case DIV_SYSTEM_YM2608:
           // ADPCM channel
-          if (dispatchChanOfChan[i]!=15) {
+          if (song.dispatchChanOfChan[i]!=15) {
             continue;
           }
           sampleMode=1;
@@ -249,7 +250,7 @@ bool DivEngine::convertLegacySampleMode() {
           break;
         case DIV_SYSTEM_YM2608_EXT:
           // ADPCM channel
-          if (dispatchChanOfChan[i]!=18) {
+          if (song.dispatchChanOfChan[i]!=18) {
             continue;
           }
           sampleMode=1;
@@ -257,7 +258,7 @@ bool DivEngine::convertLegacySampleMode() {
           break;
         case DIV_SYSTEM_YM2608_CSM:
           // ADPCM channel
-          if (dispatchChanOfChan[i]!=19) {
+          if (song.dispatchChanOfChan[i]!=19) {
             continue;
           }
           sampleMode=1;
@@ -279,21 +280,21 @@ bool DivEngine::convertLegacySampleMode() {
           break;
         case DIV_SYSTEM_Y8950:
           // Y8950 ADPCM
-          if (dispatchChanOfChan[i]!=9) {
+          if (song.dispatchChanOfChan[i]!=9) {
             continue;
           }
           sampleMode=1;
           break;
         case DIV_SYSTEM_Y8950_DRUMS:
           // Y8950 ADPCM
-          if (dispatchChanOfChan[i]!=11) {
+          if (song.dispatchChanOfChan[i]!=11) {
             continue;
           }
           sampleMode=1;
           break;
         case DIV_SYSTEM_SWAN:
           // PCM channel
-          if (dispatchChanOfChan[i]!=1) {
+          if (song.dispatchChanOfChan[i]!=1) {
             continue;
           }
           noteOffDisablesSampleMode=true;
@@ -301,7 +302,7 @@ bool DivEngine::convertLegacySampleMode() {
           break;
         case DIV_SYSTEM_VRC6:
           // pulse DAC mode
-          if (dispatchChanOfChan[i]>=2) {
+          if (song.dispatchChanOfChan[i]>=2) {
             continue;
           }
           hasLegacyToggle=true;
diff --git a/src/engine/playback.cpp b/src/engine/playback.cpp
index 72852444d..abd79aa6c 100644
--- a/src/engine/playback.cpp
+++ b/src/engine/playback.cpp
@@ -498,16 +498,16 @@ int DivEngine::dispatchCmd(DivCommand c) {
 
   // map the channel to channel of chip
   // c.dis is a copy of c.chan because we'll use it in the next call
-  c.chan=dispatchChanOfChan[c.dis];
+  c.chan=song.dispatchChanOfChan[c.dis];
 
   // dispatch command to chip dispatch
-  return disCont[dispatchOfChan[c.dis]].dispatch->dispatch(c);
+  return disCont[song.dispatchOfChan[c.dis]].dispatch->dispatch(c);
 }
 
 // this function handles per-chip normal effects
 bool DivEngine::perSystemEffect(int ch, unsigned char effect, unsigned char effectVal) {
   // don't process invalid chips
-  DivSysDef* sysDef=sysDefs[sysOfChan[ch]];
+  DivSysDef* sysDef=sysDefs[song.sysOfChan[ch]];
   if (sysDef==NULL) return false;
   // find the effect handler
   auto iter=sysDef->effectHandlers.find(effect);
@@ -530,7 +530,7 @@ bool DivEngine::perSystemEffect(int ch, unsigned char effect, unsigned char effe
 // this handles per-chip post effects...
 bool DivEngine::perSystemPostEffect(int ch, unsigned char effect, unsigned char effectVal) {
   // don't process invalid chips
-  DivSysDef* sysDef=sysDefs[sysOfChan[ch]];
+  DivSysDef* sysDef=sysDefs[song.sysOfChan[ch]];
   if (sysDef==NULL) return false;
   // find the effect handler
   auto iter=sysDef->postEffectHandlers.find(effect);
@@ -552,7 +552,7 @@ bool DivEngine::perSystemPostEffect(int ch, unsigned char effect, unsigned char
 
 // ...and this handles chip pre-effects
 bool DivEngine::perSystemPreEffect(int ch, unsigned char effect, unsigned char effectVal) {
-  DivSysDef* sysDef=sysDefs[sysOfChan[ch]];
+  DivSysDef* sysDef=sysDefs[song.sysOfChan[ch]];
   if (sysDef==NULL) return false;
   auto iter=sysDef->preEffectHandlers.find(effect);
   if (iter==sysDef->preEffectHandlers.end()) return false;
@@ -721,7 +721,7 @@ void DivEngine::processRow(int i, bool afterDelay) {
               // this hack is disabled due to its dirtiness and the fact I
               // don't feel like being compatible with a buggy tracker any further
               if (effectVal==nextSpeed) {
-                //if (sysOfChan[i]!=DIV_SYSTEM_YM2610 && sysOfChan[i]!=DIV_SYSTEM_YM2610_EXT) chan[i].delayLocked=true;
+                //if (song.sysOfChan[i]!=DIV_SYSTEM_YM2610 && song.sysOfChan[i]!=DIV_SYSTEM_YM2610_EXT) chan[i].delayLocked=true;
               } else {
                 chan[i].delayLocked=false;
               }
@@ -784,12 +784,12 @@ void DivEngine::processRow(int i, bool afterDelay) {
         chan[i].stopOnOff=false;
       }
       // depending on the system, portamento may still be disabled
-      if (disCont[dispatchOfChan[i]].dispatch->keyOffAffectsPorta(dispatchChanOfChan[i])) {
+      if (disCont[song.dispatchOfChan[i]].dispatch->keyOffAffectsPorta(song.dispatchChanOfChan[i])) {
         chan[i].portaNote=-1;
         chan[i].portaSpeed=-1;
         dispatchCmd(DivCommand(DIV_CMD_HINT_PORTA,i,CLAMP(chan[i].portaNote,-128,127),MAX(chan[i].portaSpeed,0)));
         // this here is a now-disabled hack which makes the noise channel also stop when square 3 is
-        /*if (i==2 && sysOfChan[i]==DIV_SYSTEM_SMS) {
+        /*if (i==2 && song.sysOfChan[i]==DIV_SYSTEM_SMS) {
           chan[i+1].portaNote=-1;
           chan[i+1].portaSpeed=-1;
         }*/
@@ -812,11 +812,11 @@ void DivEngine::processRow(int i, bool afterDelay) {
         dispatchCmd(DivCommand(DIV_CMD_HINT_PORTA,i,CLAMP(chan[i].portaNote,-128,127),MAX(chan[i].portaSpeed,0)));
         chan[i].stopOnOff=false;
       }
-      if (disCont[dispatchOfChan[i]].dispatch->keyOffAffectsPorta(dispatchChanOfChan[i])) {
+      if (disCont[song.dispatchOfChan[i]].dispatch->keyOffAffectsPorta(song.dispatchChanOfChan[i])) {
         chan[i].portaNote=-1;
         chan[i].portaSpeed=-1;
         dispatchCmd(DivCommand(DIV_CMD_HINT_PORTA,i,CLAMP(chan[i].portaNote,-128,127),MAX(chan[i].portaSpeed,0)));
-        /*if (i==2 && sysOfChan[i]==DIV_SYSTEM_SMS) {
+        /*if (i==2 && song.sysOfChan[i]==DIV_SYSTEM_SMS) {
           chan[i+1].portaNote=-1;
           chan[i+1].portaSpeed=-1;
         }*/
@@ -839,7 +839,7 @@ void DivEngine::processRow(int i, bool afterDelay) {
     // ...unless there's a way to trigger keyOn twice
     if (!chan[i].keyOn) {
       // the behavior of arpeggio reset upon note off varies per system
-      if (disCont[dispatchOfChan[i]].dispatch->keyOffAffectsArp(dispatchChanOfChan[i])) {
+      if (disCont[song.dispatchOfChan[i]].dispatch->keyOffAffectsArp(song.dispatchChanOfChan[i])) {
         chan[i].arp=0;
         dispatchCmd(DivCommand(DIV_CMD_HINT_ARPEGGIO,i,chan[i].arp));
       }
@@ -876,7 +876,7 @@ void DivEngine::processRow(int i, bool afterDelay) {
     // COMPAT FLAG: legacy ALWAYS_SET_VOLUME behavior (oldAlwaysSetVolume)
     // - prior to its addition, volume changes wouldn't be effective depending on the system if the volume is the same as the current one
     // - afterwards, volume change is made regardless in order to set the bottom byte of volume ("subvolume")
-    if (!song.oldAlwaysSetVolume || disCont[dispatchOfChan[i]].dispatch->getLegacyAlwaysSetVolume() || (MIN(chan[i].volMax,chan[i].volume)>>8)!=pat->newData[whatRow][DIV_PAT_VOL]) {
+    if (!song.oldAlwaysSetVolume || disCont[song.dispatchOfChan[i]].dispatch->getLegacyAlwaysSetVolume() || (MIN(chan[i].volMax,chan[i].volume)>>8)!=pat->newData[whatRow][DIV_PAT_VOL]) {
       // here we let dispatchCmd() know we can do MIDI aftertouch if there isn't a note
       if (pat->newData[whatRow][DIV_PAT_NOTE]==-1) {
         chan[i].midiAftertouch=true;
@@ -1039,7 +1039,7 @@ void DivEngine::processRow(int i, bool afterDelay) {
           // COMPAT FLAG: limit slide range
           // - this confines pitch slides from dispatch->getPortaFloor to C-8 (I think)
           // - yep, the lowest portamento note depends on the system...
-          chan[i].portaNote=song.limitSlides?disCont[dispatchOfChan[i]].dispatch->getPortaFloor(dispatchChanOfChan[i]):-60;
+          chan[i].portaNote=song.limitSlides?disCont[song.dispatchOfChan[i]].dispatch->getPortaFloor(song.dispatchChanOfChan[i]):-60;
           chan[i].portaSpeed=effectVal;
           dispatchCmd(DivCommand(DIV_CMD_HINT_PORTA,i,CLAMP(chan[i].portaNote,-128,127),MAX(chan[i].portaSpeed,0)));
           chan[i].portaStop=true;
@@ -1684,7 +1684,7 @@ void DivEngine::processRow(int i, bool afterDelay) {
             chan[i].portaNote=song.limitSlides?0x60:255;
           } else {
             // COMPAT FLAG: limit slide range
-            chan[i].portaNote=song.limitSlides?disCont[dispatchOfChan[i]].dispatch->getPortaFloor(dispatchChanOfChan[i]):-60;
+            chan[i].portaNote=song.limitSlides?disCont[song.dispatchOfChan[i]].dispatch->getPortaFloor(song.dispatchChanOfChan[i]):-60;
           }
           chan[i].portaSpeed=effectVal;
           chan[i].portaStop=true;
@@ -1726,7 +1726,7 @@ void DivEngine::nextRow() {
   if (view==DIV_STATUS_PATTERN && !skipping) {
     strcpy(pb1,"");
     strcpy(pb3,"");
-    for (int i=0; i<chans; i++) {
+    for (int i=0; i<song.chans; i++) {
       // orders
       snprintf(pb,4095," %.2x",curOrders->ord[i][curOrder]);
       strcat(pb1,pb);
@@ -1792,13 +1792,13 @@ void DivEngine::nextRow() {
   }
 
   // process row pre on all channels
-  for (int i=0; i<chans; i++) {
+  for (int i=0; i<song.chans; i++) {
     // try to find pre effects
     processRowPre(i);
   }
 
   // process row on all channels
-  for (int i=0; i<chans; i++) {
+  for (int i=0; i<song.chans; i++) {
     // COMPAT FLAG: cut/delay effect policy (delayBehavior)
     // - if not lax, reset the row delay timer so it never happens
     if (song.delayBehavior!=2) {
@@ -1895,7 +1895,7 @@ void DivEngine::nextRow() {
 
   // post row details
   // schedule pre-notes and delays (for C64 and/or a compat flag)
-  for (int i=0; i<chans; i++) {
+  for (int i=0; i<song.chans; i++) {
     DivPattern* pat=curPat[i].getPattern(curOrders->ord[i][curOrder],false);
     if (pat->newData[curRow][DIV_PAT_NOTE]!=-1) {
       // if there is a note
@@ -1904,8 +1904,8 @@ void DivEngine::nextRow() {
         if (!chan[i].legato) {
           // check whether we should fire a pre-note event
           bool wantPreNote=false;
-          if (disCont[dispatchOfChan[i]].dispatch!=NULL) {
-            wantPreNote=disCont[dispatchOfChan[i]].dispatch->getWantPreNote();
+          if (disCont[song.dispatchOfChan[i]].dispatch!=NULL) {
+            wantPreNote=disCont[song.dispatchOfChan[i]].dispatch->getWantPreNote();
             if (wantPreNote) {
               bool doPreparePreNote=true;
               int addition=0;
@@ -2039,7 +2039,7 @@ bool DivEngine::nextTick(bool noAccum, bool inhibitLowLat) {
     // this is a check that nullifies any note off event that right after a note on
     // it prevents a situation where some notes do not play
     for (int i=pendingNotes.size()-1; i>=0; i--) {
-      if (pendingNotes[i].channel<0 || pendingNotes[i].channel>=chans) continue;
+      if (pendingNotes[i].channel<0 || pendingNotes[i].channel>=song.chans) continue;
       if (pendingNotes[i].on) {
         isOn[pendingNotes[i].channel]=true;
       } else {
@@ -2058,7 +2058,7 @@ bool DivEngine::nextTick(bool noAccum, bool inhibitLowLat) {
     // fetch event
     DivNoteEvent& note=pendingNotes.front();
     // don't if channel is out of bounds or event is canceled
-    if (note.nop || note.channel<0 || note.channel>=chans) {
+    if (note.nop || note.channel<0 || note.channel>=song.chans) {
       pendingNotes.pop_front();
       continue;
     }
@@ -2077,10 +2077,10 @@ bool DivEngine::nextTick(bool noAccum, bool inhibitLowLat) {
       }
       // set volume as long as there's one associated with the event
       // and the chip has per-channel volume
-      if (note.volume>=0 && !disCont[dispatchOfChan[note.channel]].dispatch->isVolGlobal()) {
+      if (note.volume>=0 && !disCont[song.dispatchOfChan[note.channel]].dispatch->isVolGlobal()) {
         // map velocity to curve and then to equivalent chip volume
         float curvedVol=pow((float)note.volume/127.0f,midiVolExp);
-        int mappedVol=disCont[dispatchOfChan[note.channel]].dispatch->mapVelocity(dispatchChanOfChan[note.channel],curvedVol);
+        int mappedVol=disCont[song.dispatchOfChan[note.channel]].dispatch->mapVelocity(song.dispatchChanOfChan[note.channel],curvedVol);
         // fire command
         dispatchCmd(DivCommand(DIV_CMD_VOLUME,note.channel,mappedVol));
       }
@@ -2094,11 +2094,11 @@ bool DivEngine::nextTick(bool noAccum, bool inhibitLowLat) {
       chan[note.channel].lastIns=note.ins;
     } else {
       // note off
-      DivMacroInt* macroInt=disCont[dispatchOfChan[note.channel]].dispatch->getChanMacroInt(dispatchChanOfChan[note.channel]);
+      DivMacroInt* macroInt=disCont[song.dispatchOfChan[note.channel]].dispatch->getChanMacroInt(song.dispatchChanOfChan[note.channel]);
       if (macroInt!=NULL) {
         // if the current instrument has a release point in any macros and
         // volume is per-channel, send a note release instead of a note off
-        if (macroInt->hasRelease && !disCont[dispatchOfChan[note.channel]].dispatch->isVolGlobal()) {
+        if (macroInt->hasRelease && !disCont[song.dispatchOfChan[note.channel]].dispatch->isVolGlobal()) {
           dispatchCmd(DivCommand(DIV_CMD_NOTE_OFF_ENV,note.channel));
         } else {
           dispatchCmd(DivCommand(DIV_CMD_NOTE_OFF,note.channel));
@@ -2123,7 +2123,7 @@ bool DivEngine::nextTick(bool noAccum, bool inhibitLowLat) {
       // delayed row's state before it has a chance to do anything. a typical example would be
       // a delay scheduling a note-on to be simultaneous with the next row, and the next row also
       // containing a delayed note. if we don't apply the delayed row first, the world explodes.
-      for (int i=0; i<chans; i++) {
+      for (int i=0; i<song.chans; i++) {
         // delay effects
         if (chan[i].rowDelay>0) {
           if (--chan[i].rowDelay==0) {
@@ -2189,7 +2189,7 @@ bool DivEngine::nextTick(bool noAccum, bool inhibitLowLat) {
       }
 
       // process stuff such as effects
-      if (!shallStop) for (int i=0; i<chans; i++) {
+      if (!shallStop) for (int i=0; i<song.chans; i++) {
         // retrigger
         if (chan[i].retrigSpeed) {
           if (--chan[i].retrigTick<0) {
@@ -2463,7 +2463,7 @@ bool DivEngine::nextTick(bool noAccum, bool inhibitLowLat) {
                   chan[i].stopOnOff=false;
                 }
                 // depending on the system, portamento may still be disabled
-                if (disCont[dispatchOfChan[i]].dispatch->keyOffAffectsPorta(dispatchChanOfChan[i])) {
+                if (disCont[song.dispatchOfChan[i]].dispatch->keyOffAffectsPorta(song.dispatchChanOfChan[i])) {
                   chan[i].portaNote=-1;
                   chan[i].portaSpeed=-1;
                   dispatchCmd(DivCommand(DIV_CMD_HINT_PORTA,i,CLAMP(chan[i].portaNote,-128,127),MAX(chan[i].portaSpeed,0)));
@@ -2564,8 +2564,8 @@ bool DivEngine::nextTick(bool noAccum, bool inhibitLowLat) {
     shallStop=false;
     shallStopSched=false;
     // reset all chan oscs
-    for (int i=0; i<chans; i++) {
-      DivDispatchOscBuffer* buf=disCont[dispatchOfChan[i]].dispatch->getOscBuffer(dispatchChanOfChan[i]);
+    for (int i=0; i<song.chans; i++) {
+      DivDispatchOscBuffer* buf=disCont[song.dispatchOfChan[i]].dispatch->getOscBuffer(song.dispatchChanOfChan[i]);
       if (buf!=NULL) {
         buf->reset();
       }
@@ -2858,7 +2858,7 @@ void DivEngine::nextBuf(float** in, float** out, int inChans, int outChans, unsi
         case TA_MIDI_NOTE_OFF: {
           if (midiIsDirect) {
             // in direct mode, map the event directly to the channel
-            if (chan<0 || chan>=chans) break;
+            if (chan<0 || chan>=song.chans) break;
             pendingNotes.push_back(DivNoteEvent(chan,-1,-1,-1,false,false,true));
           } else {
             // find a suitable channel and add this event to the queue
@@ -2877,7 +2877,7 @@ void DivEngine::nextBuf(float** in, float** out, int inChans, int outChans, unsi
           if (msg.data[1]==0) {
             if (midiIsDirect) {
               // in direct mode, map the event directly to the channel
-              if (chan<0 || chan>=chans) break;
+              if (chan<0 || chan>=song.chans) break;
               pendingNotes.push_back(DivNoteEvent(chan,-1,-1,-1,false,false,true));
             } else {
               // find a suitable channel and add this event to the queue
@@ -2886,7 +2886,7 @@ void DivEngine::nextBuf(float** in, float** out, int inChans, int outChans, unsi
           } else {
             if (midiIsDirect) {
               // in direct mode, map the event directly to the channel
-              if (chan<0 || chan>=chans) break;
+              if (chan<0 || chan>=song.chans) break;
               pendingNotes.push_back(DivNoteEvent(chan,ins,msg.data[0]-12,msg.data[1],true,false,true));
             } else {
               // find a suitable channel and add this event to the queue
diff --git a/src/engine/song.cpp b/src/engine/song.cpp
index 7bf33dd9d..dad02d708 100644
--- a/src/engine/song.cpp
+++ b/src/engine/song.cpp
@@ -17,7 +17,7 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#include "song.h"
+#include "engine.h"
 #include "../ta-log.h"
 #include <inttypes.h>
 #include <chrono>
@@ -691,7 +691,20 @@ void DivSong::findSubSongs() {
   }
 }
 
+void DivSong::initDefaultSystemChans() {
+  for (int i=0; i<systemLen; i++) {
+    const DivSysDef* sysDef=DivEngine::getSystemDef(system[i]);
+    if (sysDef==NULL) {
+      systemChans[i]=0;
+    } else {
+      systemChans[i]=sysDef->channels;
+    }
+  }
+}
+
 void DivSong::recalcChans() {
+  logV("DivSong: recalcChans() called");
+
   bool isInsTypePossible[DIV_INS_MAX];
   chans=0;
   int chanIndex=0;
@@ -707,7 +720,7 @@ void DivSong::recalcChans() {
       dispatchFirstChan[chanIndex]=firstChan;
       chanIndex++;
 
-      DivSysDef* sysDef=DivEngine::getSystemDef(system[i]);
+      const DivSysDef* sysDef=DivEngine::getSystemDef(system[i]);
       if (sysDef!=NULL) {
         if (sysDef->chanInsType[j][0]!=DIV_INS_NULL) {
           isInsTypePossible[sysDef->chanInsType[j][0]]=true;
@@ -729,10 +742,9 @@ void DivSong::recalcChans() {
   checkAssetDir(waveDir,wave.size());
   checkAssetDir(sampleDir,sample.size());
 
-  hasLoadedSomething=true;
+  logV("%d channels (%d chips)",chans,systemLen);
 }
 
-
 void DivSong::clearSongData() {
   for (DivSubSong* i: subsong) {
     i->clearData();
diff --git a/src/engine/song.h b/src/engine/song.h
index 83414452a..e0bde3f10 100644
--- a/src/engine/song.h
+++ b/src/engine/song.h
@@ -429,9 +429,15 @@ struct DivSong {
    */
   void clearSamples();
 
+  /**
+   * set systemChans[] to default values.
+   * call recalcChans() afterwards.
+   */
+  void initDefaultSystemChans();
+
   /**
    * recalculate channel count and internal state.
-   " call after editing system[] or systemChans[].
+   * call after editing system[] or systemChans[].
    */
   void recalcChans();
 
@@ -538,6 +544,8 @@ struct DivSong {
     subsong.push_back(new DivSubSong);
     system[0]=DIV_SYSTEM_YM2612;
     system[1]=DIV_SYSTEM_SMS;
+    systemChans[0]=6;
+    systemChans[1]=4;
 
     // OPLL default instrument contest winner - piano_guitar_idk by Weeppiko
     nullInsOPLL.type=DIV_INS_OPLL;
diff --git a/src/engine/sysDef.cpp b/src/engine/sysDef.cpp
index 9f00cb7cf..2baaee2c6 100644
--- a/src/engine/sysDef.cpp
+++ b/src/engine/sysDef.cpp
@@ -51,11 +51,11 @@ int DivEngine::getChannelCount(DivSystem sys) {
 }
 
 int DivEngine::getTotalChannelCount() {
-  return chans;
+  return song.chans;
 }
 
 std::vector<DivInstrumentType>& DivEngine::getPossibleInsTypes() {
-  return possibleInsTypes;
+  return song.possibleInsTypes;
 }
 
 // for pre-dev103 modules
@@ -311,41 +311,41 @@ bool DivEngine::isSTDSystem(DivSystem sys) {
 }
 
 const char* DivEngine::getChannelName(int chan) {
-  if (chan<0 || chan>chans) return "??";
+  if (chan<0 || chan>song.chans) return "??";
   if (!curSubSong->chanName[chan].empty()) return curSubSong->chanName[chan].c_str();
-  if (sysDefs[sysOfChan[chan]]==NULL) return "??";
+  if (sysDefs[song.sysOfChan[chan]]==NULL) return "??";
   
-  const char* ret=sysDefs[sysOfChan[chan]]->chanNames[dispatchChanOfChan[chan]];
+  const char* ret=sysDefs[song.sysOfChan[chan]]->chanNames[song.dispatchChanOfChan[chan]];
   if (ret==NULL) return "??";
   return ret;
 }
 
 const char* DivEngine::getChannelShortName(int chan) {
-  if (chan<0 || chan>chans) return "??";
+  if (chan<0 || chan>song.chans) return "??";
   if (!curSubSong->chanShortName[chan].empty()) return curSubSong->chanShortName[chan].c_str();
-  if (sysDefs[sysOfChan[chan]]==NULL) return "??";
+  if (sysDefs[song.sysOfChan[chan]]==NULL) return "??";
   
-  const char* ret=sysDefs[sysOfChan[chan]]->chanShortNames[dispatchChanOfChan[chan]];
+  const char* ret=sysDefs[song.sysOfChan[chan]]->chanShortNames[song.dispatchChanOfChan[chan]];
   if (ret==NULL) return "??";
   return ret;
 }
 
 int DivEngine::getChannelType(int chan) {
-  if (chan<0 || chan>chans) return DIV_CH_NOISE;
-  if (sysDefs[sysOfChan[chan]]==NULL) return DIV_CH_NOISE;
-  return sysDefs[sysOfChan[chan]]->chanTypes[dispatchChanOfChan[chan]];
+  if (chan<0 || chan>song.chans) return DIV_CH_NOISE;
+  if (sysDefs[song.sysOfChan[chan]]==NULL) return DIV_CH_NOISE;
+  return sysDefs[song.sysOfChan[chan]]->chanTypes[song.dispatchChanOfChan[chan]];
 }
 
 DivInstrumentType DivEngine::getPreferInsType(int chan) {
-  if (chan<0 || chan>chans) return DIV_INS_STD;
-  if (sysDefs[sysOfChan[chan]]==NULL) return DIV_INS_STD;
-  return sysDefs[sysOfChan[chan]]->chanInsType[dispatchChanOfChan[chan]][0];
+  if (chan<0 || chan>song.chans) return DIV_INS_STD;
+  if (sysDefs[song.sysOfChan[chan]]==NULL) return DIV_INS_STD;
+  return sysDefs[song.sysOfChan[chan]]->chanInsType[song.dispatchChanOfChan[chan]][0];
 }
 
 DivInstrumentType DivEngine::getPreferInsSecondType(int chan) {
-  if (chan<0 || chan>chans) return DIV_INS_NULL;
-  if (sysDefs[sysOfChan[chan]]==NULL) return DIV_INS_NULL;
-  return sysDefs[sysOfChan[chan]]->chanInsType[dispatchChanOfChan[chan]][1];
+  if (chan<0 || chan>song.chans) return DIV_INS_NULL;
+  if (sysDefs[song.sysOfChan[chan]]==NULL) return DIV_INS_NULL;
+  return sysDefs[song.sysOfChan[chan]]->chanInsType[song.dispatchChanOfChan[chan]][1];
 }
 
 int DivEngine::minVGMVersion(DivSystem which) {
diff --git a/src/engine/vgmOps.cpp b/src/engine/vgmOps.cpp
index cab97710f..6b59a7e86 100644
--- a/src/engine/vgmOps.cpp
+++ b/src/engine/vgmOps.cpp
@@ -2689,8 +2689,8 @@ SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version, bool p
   bool alreadyWroteLoop=false;
   int ord=-1;
   int exportChans=0;
-  for (int i=0; i<chans; i++) {
-    if (!willExport[dispatchOfChan[i]]) continue;
+  for (int i=0; i<song.chans; i++) {
+    if (!willExport[song.dispatchOfChan[i]]) continue;
     exportChans++;
     chan[i].wentThroughNote=false;
     chan[i].goneThroughNote=false;
@@ -2710,8 +2710,8 @@ SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version, bool p
       if (trailing) beenOneLoopAlready=true;
       trailing=true;
       if (!loop) countDown=0;
-      for (int i=0; i<chans; i++) {
-        if (!willExport[dispatchOfChan[i]]) continue;
+      for (int i=0; i<song.chans; i++) {
+        if (!willExport[song.dispatchOfChan[i]]) continue;
         chan[i].wentThroughNote=false;
       }
     }
@@ -2719,8 +2719,8 @@ SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version, bool p
       switch (trailingTicks) {
         case -1: { // automatic
           bool stillHaveTo=false;
-          for (int i=0; i<chans; i++) {
-            if (!willExport[dispatchOfChan[i]]) continue;
+          for (int i=0; i<song.chans; i++) {
+            if (!willExport[song.dispatchOfChan[i]]) continue;
             if (!chan[i].goneThroughNote) continue;
             if (!chan[i].wentThroughNote) {
               stillHaveTo=true;
@@ -2777,8 +2777,8 @@ SafeWriter* DivEngine::saveVGM(bool* sysToExport, bool loop, int version, bool p
           w->writeC(0x01);
           w->writeC(prevOrder);
           w->writeC(prevRow);
-          for (int i=0; i<chans; i++) {
-            if (!willExport[dispatchOfChan[i]]) continue;
+          for (int i=0; i<song.chans; i++) {
+            if (!willExport[song.dispatchOfChan[i]]) continue;
             w->writeC(curSubSong->orders.ord[i][prevOrder]);
           }
         }
diff --git a/src/engine/wavOps.cpp b/src/engine/wavOps.cpp
index 899f729f8..d65af451d 100644
--- a/src/engine/wavOps.cpp
+++ b/src/engine/wavOps.cpp
@@ -63,7 +63,7 @@ void DivEngine::getTotalAudioFiles(int &files) {
       break;
     }
     case DIV_EXPORT_MODE_MANY_CHAN: {
-      for (int i=0; i<chans; i++) {
+      for (int i=0; i<song.chans; i++) {
         if (!exportChannelMask[i]) continue;
 
         files++;
@@ -71,7 +71,7 @@ void DivEngine::getTotalAudioFiles(int &files) {
         if (getChannelType(i)==5) {
           i++;
           while (true) {
-            if (i>=chans) break;
+            if (i>=song.chans) break;
             if (getChannelType(i)!=5) break;
             i++;
           }
@@ -425,7 +425,7 @@ void DivEngine::runExportThread() {
 
       logI("rendering to files...");
       
-      for (int i=0; i<chans; i++) {
+      for (int i=0; i<song.chans; i++) {
         if (!exportChannelMask[i]) continue;
 
         SNDFILE* sf;
@@ -476,19 +476,19 @@ void DivEngine::runExportThread() {
 
         MAP_BITRATE;
 
-        for (int j=0; j<chans; j++) {
+        for (int j=0; j<song.chans; j++) {
           bool mute=(j!=i);
           isMuted[j]=mute;
         }
         if (getChannelType(i)==5) {
-          for (int j=i; j<chans; j++) {
+          for (int j=i; j<song.chans; j++) {
             if (getChannelType(j)!=5) break;
             isMuted[j]=false;
           }
         }
-        for (int j=0; j<chans; j++) {
-          if (disCont[dispatchOfChan[j]].dispatch!=NULL) {
-            disCont[dispatchOfChan[j]].dispatch->muteChannel(dispatchChanOfChan[j],isMuted[j]);
+        for (int j=0; j<song.chans; j++) {
+          if (disCont[song.dispatchOfChan[j]].dispatch!=NULL) {
+            disCont[song.dispatchOfChan[j]].dispatch->muteChannel(song.dispatchChanOfChan[j],isMuted[j]);
           }
         }
         
@@ -549,7 +549,7 @@ void DivEngine::runExportThread() {
         if (getChannelType(i)==5) {
           i++;
           while (true) {
-            if (i>=chans) break;
+            if (i>=song.chans) break;
             if (getChannelType(i)!=5) break;
             i++;
           }
@@ -564,10 +564,10 @@ void DivEngine::runExportThread() {
         delete[] outBuf[i];
       }
 
-      for (int i=0; i<chans; i++) {
+      for (int i=0; i<song.chans; i++) {
         isMuted[i]=false;
-        if (disCont[dispatchOfChan[i]].dispatch!=NULL) {
-          disCont[dispatchOfChan[i]].dispatch->muteChannel(dispatchChanOfChan[i],false);
+        if (disCont[song.dispatchOfChan[i]].dispatch!=NULL) {
+          disCont[song.dispatchOfChan[i]].dispatch->muteChannel(song.dispatchChanOfChan[i],false);
         }
       }
 
@@ -642,7 +642,7 @@ bool DivEngine::saveAudio(const char* path, DivAudioExportOptions options) {
     quitDispatch();
     initDispatch(true);
     renderSamplesP();
-    for (int i=0; i<chans; i++) {
+    for (int i=0; i<song.chans; i++) {
       if (isMutedBefore[i]) {
         muteChannel(i,true);
       }
@@ -680,7 +680,7 @@ void DivEngine::finishAudioFile() {
     quitDispatch();
     initDispatch(false);
     renderSamplesP();
-    for (int i=0; i<chans; i++) {
+    for (int i=0; i<song.chans; i++) {
       if (isMutedBefore[i]) {
         muteChannel(i,true);
       }
diff --git a/src/gui/chanOsc.cpp b/src/gui/chanOsc.cpp
index 30c854520..3bd6bf415 100644
--- a/src/gui/chanOsc.cpp
+++ b/src/gui/chanOsc.cpp
@@ -868,15 +868,15 @@ void FurnaceGUI::drawChanOsc() {
                         break;
                       }
                       case 's': {
-                        text+=e->getSystemName(e->sysOfChan[ch]);
+                        text+=e->getSystemName(e->song.sysOfChan[ch]);
                         break;
                       }
                       case 'p': {
-                        text+=FurnaceGUI::getSystemPartNumber(e->sysOfChan[ch],e->song.systemFlags[e->dispatchOfChan[ch]]);
+                        text+=FurnaceGUI::getSystemPartNumber(e->song.sysOfChan[ch],e->song.systemFlags[e->song.dispatchOfChan[ch]]);
                         break;
                       }
                       case 'S': {
-                        text+=fmt::sprintf("%d",e->dispatchOfChan[ch]);
+                        text+=fmt::sprintf("%d",e->song.dispatchOfChan[ch]);
                         break;
                       }
                       case 'v': {
diff --git a/src/gui/channels.cpp b/src/gui/channels.cpp
index 091a4103a..34f7caab3 100644
--- a/src/gui/channels.cpp
+++ b/src/gui/channels.cpp
@@ -78,7 +78,7 @@ void FurnaceGUI::drawChannels() {
           ImGui::Button(ICON_FA_ARROWS "##ChanDrag");
           ImGui::EndDragDropSource();
         } else if (ImGui::IsItemHovered()) {
-          ImGui::SetTooltip(_("%s #%d\n(drag to swap channels)\n(Shift-drag to copy channel contents)"),e->getSystemName(e->sysOfChan[i]),e->dispatchChanOfChan[i]);
+          ImGui::SetTooltip(_("%s #%d\n(drag to swap channels)\n(Shift-drag to copy channel contents)"),e->getSystemName(e->song.sysOfChan[i]),e->song.dispatchChanOfChan[i]);
         }
         if (ImGui::BeginDragDropTarget()) {
           const ImGuiPayload* dragItem=ImGui::AcceptDragDropPayload("FUR_CHAN");
diff --git a/src/gui/debugWindow.cpp b/src/gui/debugWindow.cpp
index 8e152ebec..96d0a2dce 100644
--- a/src/gui/debugWindow.cpp
+++ b/src/gui/debugWindow.cpp
@@ -118,11 +118,11 @@ void FurnaceGUI::drawDebug() {
       ImGui::Columns(e->getTotalChannelCount());
       for (int i=0; i<e->getTotalChannelCount(); i++) {
         void* ch=e->getDispatchChanState(i);
-        ImGui::TextColored(uiColors[GUI_COLOR_ACCENT_PRIMARY],"Ch. %d: %d, %d",i,e->dispatchOfChan[i],e->dispatchChanOfChan[i]);
+        ImGui::TextColored(uiColors[GUI_COLOR_ACCENT_PRIMARY],"Ch. %d: %d, %d",i,e->song.dispatchOfChan[i],e->song.dispatchChanOfChan[i]);
         if (ch==NULL) {
           ImGui::Text("NULL");
         } else {
-          putDispatchChan(ch,e->dispatchChanOfChan[i],e->sysOfChan[i]);
+          putDispatchChan(ch,e->song.dispatchChanOfChan[i],e->song.sysOfChan[i]);
         }
         ImGui::NextColumn();
       }
diff --git a/src/gui/effectList.cpp b/src/gui/effectList.cpp
index e4339e301..284b8cb1a 100644
--- a/src/gui/effectList.cpp
+++ b/src/gui/effectList.cpp
@@ -15,7 +15,7 @@ void FurnaceGUI::drawEffectList() {
     float availB=ImGui::GetContentRegionAvail().x-ImGui::GetFrameHeightWithSpacing();
     if (availB>0) {
       ImGui::PushTextWrapPos(availB);
-      ImGui::TextWrapped(_("Chip at cursor: %s"),e->getSystemName(e->sysOfChan[cursor.xCoarse]));
+      ImGui::TextWrapped(_("Chip at cursor: %s"),e->getSystemName(e->song.sysOfChan[cursor.xCoarse]));
       ImGui::PopTextWrapPos();
     }
     effectSearch.Draw(_("Search"));
@@ -55,7 +55,7 @@ void FurnaceGUI::drawEffectList() {
         }
         prevName=name;
         if (fxColors[i]==GUI_COLOR_PATTERN_EFFECT_PANNING) {
-          DivDispatch* dispatch=e->getDispatch(e->dispatchOfChan[cursor.xCoarse]);
+          DivDispatch* dispatch=e->getDispatch(e->song.dispatchOfChan[cursor.xCoarse]);
           if (dispatch!=NULL) {
             int outputs=dispatch->getOutputCount();
             if (outputs<2) {
diff --git a/src/gui/pattern.cpp b/src/gui/pattern.cpp
index 46f799c27..e905d8762 100644
--- a/src/gui/pattern.cpp
+++ b/src/gui/pattern.cpp
@@ -1458,7 +1458,7 @@ void FurnaceGUI::drawPattern() {
 
           for (int j=0; j<8; j++) {
             if (pair.pairs[j]==-1) continue;
-            int pairCh=e->dispatchFirstChan[i]+pair.pairs[j];
+            int pairCh=e->song.dispatchFirstChan[i]+pair.pairs[j];
             if (!e->curSubSong->chanShow[pairCh]) {
               continue;
             }
@@ -1514,7 +1514,7 @@ void FurnaceGUI::drawPattern() {
 
           for (int j=0; j<8; j++) {
             if (pair.pairs[j]==-1) continue;
-            int pairCh=e->dispatchFirstChan[i]+pair.pairs[j];
+            int pairCh=e->song.dispatchFirstChan[i]+pair.pairs[j];
             if (!e->curSubSong->chanShow[pairCh]) {
               continue;
             }
diff --git a/src/log.cpp b/src/log.cpp
index 215b4ddfc..0504c8f00 100644
--- a/src/log.cpp
+++ b/src/log.cpp
@@ -32,8 +32,8 @@ int logLevel=LOGLEVEL_TRACE;
 int logLevel=LOGLEVEL_TRACE; // until done
 #endif
 
-FILE* logOut;
-FILE* logFile;
+FILE* logOut=NULL;
+FILE* logFile=NULL;
 char* logFileBuf;
 char* logFileWriteBuf;
 unsigned int logFilePosI;
@@ -140,6 +140,7 @@ int writeLog(int level, const char* msg, fmt::printf_args args) {
   }
 
   if (logLevel<level) return 0;
+  if (logOut==NULL) return -1;
   switch (level) {
     case LOGLEVEL_ERROR:
       return fmt::fprintf(logOut,"\x1b[1;31m[ERROR]\x1b[m %s\n",logEntries[pos].text);