diff --git a/CMakeLists.txt b/CMakeLists.txt
index af46dee1..1a090963 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -290,6 +290,7 @@ src/engine/config.cpp
 src/engine/dispatchContainer.cpp
 src/engine/engine.cpp
 src/engine/fileOps.cpp
+src/engine/fileOpsIns.cpp
 src/engine/filter.cpp
 src/engine/instrument.cpp
 src/engine/macroInt.cpp
diff --git a/src/engine/engine.cpp b/src/engine/engine.cpp
index d465a1be..c26058e6 100644
--- a/src/engine/engine.cpp
+++ b/src/engine/engine.cpp
@@ -1270,749 +1270,6 @@ int DivEngine::addInstrumentPtr(DivInstrument* which) {
   return song.insLen;
 }
 
-enum DivInsFormats {
-  DIV_INSFORMAT_DMP,
-  DIV_INSFORMAT_TFI,
-  DIV_INSFORMAT_VGI,
-  DIV_INSFORMAT_FTI,
-  DIV_INSFORMAT_BTI,
-  DIV_INSFORMAT_S3I,
-  DIV_INSFORMAT_SBI,
-  DIV_INSFORMAT_OPM
-};
-
-// TODO: re-organize this function to:
-// - support replacing instruments
-// - support instrument formats which contain multiple instruments
-std::vector<DivInstrument*> DivEngine::instrumentFromFile(const char* path) {
-  std::vector<DivInstrument*> ret;
-  warnings="";
-
-  const char* pathRedux=strrchr(path,DIR_SEPARATOR);
-  if (pathRedux==NULL) {
-    pathRedux=path;
-  } else {
-    pathRedux++;
-  }
-  String stripPath;
-  const char* pathReduxEnd=strrchr(pathRedux,'.');
-  if (pathReduxEnd==NULL) {
-    stripPath=pathRedux;
-  } else {
-    for (const char* i=pathRedux; i!=pathReduxEnd && (*i); i++) {
-      stripPath+=*i;
-    }
-  }
-
-  FILE* f=ps_fopen(path,"rb");
-  if (f==NULL) {
-    lastError=strerror(errno);
-    return ret;
-  }
-  unsigned char* buf;
-  ssize_t len;
-  if (fseek(f,0,SEEK_END)!=0) {
-    lastError=strerror(errno);
-    fclose(f);
-    return ret;
-  }
-  len=ftell(f);
-  if (len<0) {
-    lastError=strerror(errno);
-    fclose(f);
-    return ret;
-  }
-  if (len==0) {
-    lastError=strerror(errno);
-    fclose(f);
-    return ret;
-  }
-  if (fseek(f,0,SEEK_SET)!=0) {
-    lastError=strerror(errno);
-    fclose(f);
-    return ret;
-  }
-  buf=new unsigned char[len];
-  if (fread(buf,1,len,f)!=(size_t)len) {
-    logW("did not read entire instrument file buffer!\n");
-    lastError="did not read entire instrument file!";
-    delete[] buf;
-    return ret;
-  }
-  fclose(f);
-
-  SafeReader reader=SafeReader(buf,len);
-
-  unsigned char magic[16];
-  bool isFurnaceInstr=false;
-  try {
-    reader.read(magic,16);
-    if (memcmp("-Furnace instr.-",magic,16)==0) {
-      isFurnaceInstr=true;
-    }
-  } catch (EndOfFileException& e) {
-    reader.seek(0,SEEK_SET);
-  }
-
-  DivInstrument* ins=new DivInstrument;
-  if (isFurnaceInstr) {
-    try {
-      short version=reader.readS();
-      reader.readS(); // reserved
-
-      if (version>DIV_ENGINE_VERSION) {
-        warnings="this instrument is made with a more recent version of Furnace!";
-      }
-
-      unsigned int dataPtr=reader.readI();
-      reader.seek(dataPtr,SEEK_SET);
-
-      if (ins->readInsData(reader,version)!=DIV_DATA_SUCCESS) {
-        lastError="invalid instrument header/data!";
-        delete ins;
-        delete[] buf;
-        return ret;
-      }
-    } catch (EndOfFileException& e) {
-      lastError="premature end of file";
-      logE("premature end of file!\n");
-      delete ins;
-      delete[] buf;
-      return ret;
-    }
-  } else { // read as a different format
-    const char* ext=strrchr(path,'.');
-    DivInsFormats format=DIV_INSFORMAT_DMP;
-    if (ext!=NULL) {
-      String extS;
-      for (; *ext; ext++) {
-        char i=*ext;
-        if (i>='A' && i<='Z') {
-          i+='a'-'A';
-        }
-        extS+=i;
-      }
-      if (extS==String(".dmp")) {
-        format=DIV_INSFORMAT_DMP;
-      } else if (extS==String(".tfi")) {
-        format=DIV_INSFORMAT_TFI;
-      } else if (extS==String(".vgi")) {
-        format=DIV_INSFORMAT_VGI;
-      } else if (extS==String(".fti")) {
-        format=DIV_INSFORMAT_FTI;
-      } else if (extS==String(".bti")) {
-        format=DIV_INSFORMAT_BTI;
-      } else if (extS==String(".s3i")) {
-        format = DIV_INSFORMAT_S3I;
-      } else if (extS==String(".sbi")) {
-        format = DIV_INSFORMAT_SBI;
-      }
-    }
-
-    // TDOO these really should be re-organized to separate functions per instrument file type.
-    switch (format) {
-      case DIV_INSFORMAT_DMP: {
-        // this is a ridiculous mess
-        unsigned char version=0;
-        unsigned char sys=0;
-        try {
-          reader.seek(0,SEEK_SET);
-          version=reader.readC();
-          logD(".dmp version %d\n",version);
-        } catch (EndOfFileException& e) {
-          lastError="premature end of file";
-          logE("premature end of file!\n");
-          delete ins;
-          delete[] buf;
-          return ret;
-        }
-
-        if (version>11) {
-          lastError="unknown instrument version!";
-          delete ins;
-          delete[] buf;
-          return ret;
-        }
-
-        ins->name=stripPath;
-
-        if (version>=11) { // 1.0
-          try {
-            sys=reader.readC();
-      
-            switch (sys) {
-              case 1: // YMU759
-                ins->type=DIV_INS_FM;
-                logD("instrument type is YMU759\n");
-                break;
-              case 2: // Genesis
-                ins->type=DIV_INS_FM;
-                logD("instrument type is Genesis\n");
-                break;
-              case 3: // SMS
-                ins->type=DIV_INS_STD;
-                logD("instrument type is SMS\n");
-                break;
-              case 4: // Game Boy
-                ins->type=DIV_INS_GB;
-                logD("instrument type is Game Boy\n");
-                break;
-              case 5: // PC Engine
-                ins->type=DIV_INS_PCE;
-                logD("instrument type is PC Engine\n");
-                break;
-              case 6: // NES
-                ins->type=DIV_INS_STD;
-                logD("instrument type is NES\n");
-                break;
-              case 7: case 0x17: // C64
-                ins->type=DIV_INS_C64;
-                logD("instrument type is C64\n");
-                break;
-              case 8: // Arcade
-                ins->type=DIV_INS_FM;
-                logD("instrument type is Arcade\n");
-                break;
-              default:
-                logD("instrument type is unknown\n");
-                lastError="unknown instrument type!";
-                delete ins;
-                delete[] buf;
-                return ret;
-                break;
-            }
-          } catch (EndOfFileException& e) {
-            lastError="premature end of file";
-            logE("premature end of file!\n");
-            delete ins;
-            delete[] buf;
-            return ret;
-          }
-        }
-
-        try {
-          bool mode=true;
-          if (version>1) {
-            mode=reader.readC();
-            logD("instrument mode is %d\n",mode);
-            if (mode==0) {
-              if (version<11) {
-                ins->type=DIV_INS_STD;
-              }
-            } else {
-              ins->type=DIV_INS_FM;
-            }
-          } else {
-            ins->type=DIV_INS_FM;
-          }
-
-          if (mode) { // FM
-            logD("reading FM data...\n");
-            if (version<10) {
-              if (version>1) {
-                ins->fm.ops=reader.readC()?4:2;
-              } else {
-                ins->fm.ops=reader.readC()?2:4;
-              }
-            } else {
-              ins->fm.ops=4;
-            }
-            if (version>1) { // HELP! in which version of the format did we start storing FMS!
-              ins->fm.fms=reader.readC();
-            }
-            ins->fm.fb=reader.readC();
-            ins->fm.alg=reader.readC();
-            // DITTO
-            if (sys!=1) ins->fm.ams=reader.readC();
-
-            for (int j=0; j<ins->fm.ops; j++) {
-              logD("OP%d is at %d\n",j,reader.tell());
-              ins->fm.op[j].mult=reader.readC();
-              ins->fm.op[j].tl=reader.readC();
-              ins->fm.op[j].ar=reader.readC();
-              ins->fm.op[j].dr=reader.readC();
-              ins->fm.op[j].sl=reader.readC();
-              ins->fm.op[j].rr=reader.readC();
-              ins->fm.op[j].am=reader.readC();
-              // what the hell how do I tell!
-              if (sys==1) { // YMU759
-                ins->fm.op[j].ws=reader.readC();
-                ins->fm.op[j].ksl=reader.readC();
-                ins->fm.op[j].vib=reader.readC();
-                ins->fm.op[j].egt=reader.readC();
-                ins->fm.op[j].sus=reader.readC();
-                ins->fm.op[j].ksr=reader.readC();
-                ins->fm.op[j].dvb=reader.readC();
-                ins->fm.op[j].dam=reader.readC();
-              } else {
-                ins->fm.op[j].rs=reader.readC();
-                ins->fm.op[j].dt=reader.readC();
-                ins->fm.op[j].dt2=ins->fm.op[j].dt>>4;
-                ins->fm.op[j].dt&=15;
-                ins->fm.op[j].d2r=reader.readC();
-                ins->fm.op[j].ssgEnv=reader.readC();
-              }
-            }
-          } else { // STD
-            logD("reading STD data...\n");
-            if (ins->type!=DIV_INS_GB) {
-              ins->std.volMacroLen=reader.readC();
-              if (version>5) {
-                for (int i=0; i<ins->std.volMacroLen; i++) {
-                  ins->std.volMacro[i]=reader.readI();
-                }
-              } else {
-                for (int i=0; i<ins->std.volMacroLen; i++) {
-                  ins->std.volMacro[i]=reader.readC();
-                }
-              }
-              if (version<11) for (int i=0; i<ins->std.volMacroLen; i++) {
-                if (ins->std.volMacro[i]>15 && ins->type==DIV_INS_STD) ins->type=DIV_INS_PCE;
-              }
-              if (ins->std.volMacroLen>0) {
-                ins->std.volMacroOpen=true;
-                ins->std.volMacroLoop=reader.readC();
-              } else {
-                ins->std.volMacroOpen=false;
-              }
-            }
-
-            ins->std.arpMacroLen=reader.readC();
-            if (version>5) {
-              for (int i=0; i<ins->std.arpMacroLen; i++) {
-                ins->std.arpMacro[i]=reader.readI();
-              }
-            } else {
-              for (int i=0; i<ins->std.arpMacroLen; i++) {
-                ins->std.arpMacro[i]=reader.readC();
-              }
-            }
-            if (ins->std.arpMacroLen>0) {
-              ins->std.arpMacroOpen=true;
-              ins->std.arpMacroLoop=reader.readC();
-            } else {
-              ins->std.arpMacroOpen=false;
-            }
-            if (version>8) { // TODO: when?
-              ins->std.arpMacroMode=reader.readC();
-            }
-
-            ins->std.dutyMacroLen=reader.readC();
-            if (version>5) {
-              for (int i=0; i<ins->std.dutyMacroLen; i++) {
-                ins->std.dutyMacro[i]=reader.readI();
-              }
-            } else {
-              for (int i=0; i<ins->std.dutyMacroLen; i++) {
-                ins->std.dutyMacro[i]=reader.readC();
-              }
-            }
-            if (ins->std.dutyMacroLen>0) {
-              ins->std.dutyMacroOpen=true;
-              ins->std.dutyMacroLoop=reader.readC();
-            } else {
-              ins->std.dutyMacroOpen=false;
-            }
-
-            ins->std.waveMacroLen=reader.readC();
-            if (version>5) {
-              for (int i=0; i<ins->std.waveMacroLen; i++) {
-                ins->std.waveMacro[i]=reader.readI();
-              }
-            } else {
-              for (int i=0; i<ins->std.waveMacroLen; i++) {
-                ins->std.waveMacro[i]=reader.readC();
-              }
-            }
-            if (ins->std.waveMacroLen>0) {
-              ins->std.waveMacroOpen=true;
-              ins->std.waveMacroLoop=reader.readC();
-            } else {
-              ins->std.waveMacroOpen=false;
-            }
-
-            if (ins->type==DIV_INS_C64) {
-              ins->c64.triOn=reader.readC();
-              ins->c64.sawOn=reader.readC();
-              ins->c64.pulseOn=reader.readC();
-              ins->c64.noiseOn=reader.readC();
-
-              ins->c64.a=reader.readC();
-              ins->c64.d=reader.readC();
-              ins->c64.s=reader.readC();
-              ins->c64.r=reader.readC();
-
-              ins->c64.duty=(reader.readC()*4095)/100;
-
-              ins->c64.ringMod=reader.readC();
-              ins->c64.oscSync=reader.readC();
-              ins->c64.toFilter=reader.readC();
-              if (version<0x07) { // TODO: UNSURE
-                ins->c64.volIsCutoff=reader.readI();
-              } else {
-                ins->c64.volIsCutoff=reader.readC();
-              }
-              ins->c64.initFilter=reader.readC();
-
-              ins->c64.res=reader.readC();
-              ins->c64.cut=(reader.readC()*2047)/100;
-              ins->c64.hp=reader.readC();
-              ins->c64.bp=reader.readC();
-              ins->c64.lp=reader.readC();
-              ins->c64.ch3off=reader.readC();
-            }
-            if (ins->type==DIV_INS_GB) {
-              ins->gb.envVol=reader.readC();
-              ins->gb.envDir=reader.readC();
-              ins->gb.envLen=reader.readC();
-              ins->gb.soundLen=reader.readC();
-            }
-          }
-        } catch (EndOfFileException& e) {
-          lastError="premature end of file";
-          logE("premature end of file!\n");
-          delete ins;
-          delete[] buf;
-          return ret;
-        }
-        break;
-      }
-      case DIV_INSFORMAT_TFI:
-        try {
-          reader.seek(0,SEEK_SET);
-
-          ins->type=DIV_INS_FM;
-          ins->name=stripPath;
-          
-          ins->fm.alg=reader.readC();
-          ins->fm.fb=reader.readC();
-
-          for (int i=0; i<4; i++) {
-            DivInstrumentFM::Operator& op=ins->fm.op[i];
-
-            op.mult=reader.readC();
-            op.dt=reader.readC();
-            op.tl=reader.readC();
-            op.rs=reader.readC();
-            op.ar=reader.readC();
-            op.dr=reader.readC();
-            op.d2r=reader.readC();
-            op.rr=reader.readC();
-            op.sl=reader.readC();
-            op.ssgEnv=reader.readC();
-          }
-        } catch (EndOfFileException& e) {
-          lastError="premature end of file";
-          logE("premature end of file!\n");
-          delete ins;
-          delete[] buf;
-          return ret;
-        }
-        break;
-      case DIV_INSFORMAT_VGI:
-        try {
-          reader.seek(0,SEEK_SET);
-
-          ins->type=DIV_INS_FM;
-          ins->name=stripPath;
-          
-          ins->fm.alg=reader.readC();
-          ins->fm.fb=reader.readC();
-          unsigned char fmsams=reader.readC();
-          ins->fm.fms=fmsams&7;
-          ins->fm.ams=fmsams>>4;
-
-          for (int i=0; i<4; i++) {
-            DivInstrumentFM::Operator& op=ins->fm.op[i];
-
-            op.mult=reader.readC();
-            op.dt=reader.readC();
-            op.tl=reader.readC();
-            op.rs=reader.readC();
-            op.ar=reader.readC();
-            op.dr=reader.readC();
-            if (op.dr&0x80) {
-              op.am=1;
-              op.dr&=0x7f;
-            }
-            op.d2r=reader.readC();
-            op.rr=reader.readC();
-            op.sl=reader.readC();
-            op.ssgEnv=reader.readC();
-          }
-        } catch (EndOfFileException& e) {
-          lastError="premature end of file";
-          logE("premature end of file!\n");
-          delete ins;
-          delete[] buf;
-          return ret;
-        }
-        break;
-      case DIV_INSFORMAT_FTI: // TODO
-        break;
-      case DIV_INSFORMAT_BTI: // TODO
-        break;
-      case DIV_INSFORMAT_OPM: // TODO
-        break;
-      case DIV_INSFORMAT_S3I:
-        try {
-          reader.seek(0, SEEK_SET);
-
-          uint8_t s3i_type = reader.readC();
-
-          if (s3i_type >= 2) {
-            ins->type = DIV_INS_OPL;
-            // skip internal filename - we'll use the long name description
-            reader.seek(12, SEEK_CUR);
-
-            // skip reserved bytes
-            reader.seek(3, SEEK_CUR);
-
-            // 12-byte opl value
-            uint8_t s3i_Mcharacteristics = reader.readC();
-            uint8_t s3i_Ccharacteristics = reader.readC();
-            uint8_t s3i_Mscaling_output = reader.readC();
-            uint8_t s3i_Cscaling_output = reader.readC();
-            uint8_t s3i_Meg_AD = reader.readC();
-            uint8_t s3i_Ceg_AD = reader.readC();
-            uint8_t s3i_Meg_SR = reader.readC();
-            uint8_t s3i_Ceg_SR = reader.readC();
-            uint8_t s3i_Mwave = reader.readC();
-            uint8_t s3i_Cwave = reader.readC();
-            uint8_t s3i_FeedConnect = reader.readC();
-            
-            DivInstrumentFM::Operator& opM = ins->fm.op[0];
-            DivInstrumentFM::Operator& opC = ins->fm.op[1];
-            ins->fm.ops = 2;
-            opM.mult = s3i_Mcharacteristics & 0xF;
-            opM.ksr = ((s3i_Mcharacteristics >> 4) & 0x1);
-            opM.sus = ((s3i_Mcharacteristics >> 5) & 0x1);
-            opM.vib = ((s3i_Mcharacteristics >> 6) & 0x1);
-            opM.am = ((s3i_Mcharacteristics >> 7) & 0x1);
-            opM.tl = s3i_Mscaling_output & 0x3F;
-            opM.ksl = ((s3i_Mscaling_output >> 6) & 0x3);
-            opM.ar = ((s3i_Meg_AD >> 4) & 0xF);
-            opM.dr = (s3i_Meg_AD & 0xF);
-            opM.rr = (s3i_Meg_SR & 0xF);
-            opM.sl = ((s3i_Meg_SR >> 4) & 0xF);
-            opM.ws = s3i_Mwave;
-
-            ins->fm.alg = (s3i_FeedConnect & 0x1);
-            ins->fm.fb = ((s3i_FeedConnect >> 1) & 0x7);
-
-            opC.mult = s3i_Ccharacteristics & 0xF;
-            opC.ksr = ((s3i_Ccharacteristics >> 4) & 0x1);
-            opC.sus = ((s3i_Ccharacteristics >> 5) & 0x1);
-            opC.vib = ((s3i_Ccharacteristics >> 6) & 0x1);
-            opC.am = ((s3i_Ccharacteristics >> 7) & 0x1);
-            opC.tl = s3i_Cscaling_output & 0x3F;
-            opC.ksl = ((s3i_Cscaling_output >> 6) & 0x3);
-            opC.ar = ((s3i_Ceg_AD >> 4) & 0xF);
-            opC.dr = (s3i_Ceg_AD & 0xF);
-            opC.rr = (s3i_Ceg_SR & 0xF);
-            opC.sl = ((s3i_Ceg_SR >> 4) & 0xF);
-            opC.ws = s3i_Cwave;
-
-            // Skip more stuff we don't need
-            reader.seek(21, SEEK_CUR);
-          } else {
-            logE("S3I PCM samples currently not supported.");
-          }
-          ins->name = reader.readString(28);
-          int s3i_signature = reader.readI();
-
-          if (s3i_signature != 0x49524353) {
-            logW("S3I signature invalid.");
-          };
-        }
-        catch (EndOfFileException& e) {
-          lastError = "premature end of file";
-          logE("premature end of file!\n");
-          delete ins;
-          delete[] buf;
-          return ret;
-        }
-        break;
-      case DIV_INSFORMAT_SBI:
-        try {
-          reader.seek(0, SEEK_SET);
-          ins->type = DIV_INS_OPL;
-
-          int sbi_header = reader.readI();
-          // SBI header determines format
-          bool is_2op = (sbi_header == 0x1A494253); // SBI\x1A
-          bool is_4op = (sbi_header == 0x1A504F34); // 4OP\x1A
-          bool is_6op = (sbi_header == 0x1A504F36); // 6OP\x1A - Freq Monster 801-specific
-
-          // 32-byte null terminated instrument name
-          ins->name = reader.readString(32);
-
-          // 2op SBI
-          uint8_t sbi_Mcharacteristics = reader.readC();
-          uint8_t sbi_Ccharacteristics = reader.readC();
-          uint8_t sbi_Mscaling_output = reader.readC();
-          uint8_t sbi_Cscaling_output = reader.readC();
-          uint8_t sbi_Meg_AD = reader.readC();
-          uint8_t sbi_Ceg_AD = reader.readC();
-          uint8_t sbi_Meg_SR = reader.readC();
-          uint8_t sbi_Ceg_SR = reader.readC();
-          uint8_t sbi_Mwave = reader.readC();
-          uint8_t sbi_Cwave = reader.readC();
-          uint8_t sbi_FeedConnect = reader.readC();
-
-          // 4op SBI
-          uint8_t sbi_M4characteristics;
-          uint8_t sbi_C4characteristics;
-          uint8_t sbi_M4scaling_output;
-          uint8_t sbi_C4scaling_output;
-          uint8_t sbi_M4eg_AD;
-          uint8_t sbi_C4eg_AD;
-          uint8_t sbi_M4eg_SR;
-          uint8_t sbi_C4eg_SR;
-          uint8_t sbi_M4wave;
-          uint8_t sbi_C4wave;
-          uint8_t sbi_4opConnect;
-          
-          if (is_2op) {
-            DivInstrumentFM::Operator& opM = ins->fm.op[0];
-            DivInstrumentFM::Operator& opC = ins->fm.op[1];
-            ins->fm.ops = 2;
-            opM.mult = sbi_Mcharacteristics & 0xF;
-            opM.ksr = ((sbi_Mcharacteristics >> 4) & 0x1);
-            opM.sus = ((sbi_Mcharacteristics >> 5) & 0x1);
-            opM.vib = ((sbi_Mcharacteristics >> 6) & 0x1);
-            opM.am = ((sbi_Mcharacteristics >> 7) & 0x1);
-            opM.tl = sbi_Mscaling_output & 0x3F;
-            opM.ksl = ((sbi_Mscaling_output >> 6) & 0x3);
-            opM.ar = ((sbi_Meg_AD >> 4) & 0xF);
-            opM.dr = (sbi_Meg_AD & 0xF);
-            opM.rr = (sbi_Meg_SR & 0xF);
-            opM.sl = ((sbi_Meg_SR >> 4) & 0xF);
-            opM.ws = sbi_Mwave;
-
-            ins->fm.alg = (sbi_FeedConnect & 0x1);
-            ins->fm.fb = ((sbi_FeedConnect >> 1) & 0x7);
-
-            opC.mult = sbi_Ccharacteristics & 0xF;
-            opC.ksr = ((sbi_Ccharacteristics >> 4) & 0x1);
-            opC.sus = ((sbi_Ccharacteristics >> 5) & 0x1);
-            opC.vib = ((sbi_Ccharacteristics >> 6) & 0x1);
-            opC.am = ((sbi_Ccharacteristics >> 7) & 0x1);
-            opC.tl = sbi_Cscaling_output & 0x3F;
-            opC.ksl = ((sbi_Cscaling_output >> 6) & 0x3);
-            opC.ar = ((sbi_Ceg_AD >> 4) & 0xF);
-            opC.dr = (sbi_Ceg_AD & 0xF);
-            opC.rr = (sbi_Ceg_SR & 0xF);
-            opC.sl = ((sbi_Ceg_SR >> 4) & 0xF);
-            opC.ws = sbi_Cwave;
-
-            // Ignore rest of file - rest is 'reserved padding'.
-            reader.seek(0, SEEK_END);
-          }
-
-          if (is_4op || is_6op) {
-            // Operator placement is different so need to place in correct registers.
-            // Note: 6op is an unofficial extension of 4op SBIs by Darron Broad (Freq Monster 801).
-            // We'll only use the 4op portion here for pure OPL3.
-            DivInstrumentFM::Operator& opM = ins->fm.op[0];
-            DivInstrumentFM::Operator& opC = ins->fm.op[2];
-            DivInstrumentFM::Operator& opM4 = ins->fm.op[1];
-            DivInstrumentFM::Operator& opC4 = ins->fm.op[3];
-            ins->fm.ops = 4;
-
-            sbi_M4characteristics = reader.readC();
-            sbi_C4characteristics = reader.readC();
-            sbi_M4scaling_output = reader.readC();
-            sbi_C4scaling_output = reader.readC();
-            sbi_M4eg_AD = reader.readC();
-            sbi_C4eg_AD = reader.readC();
-            sbi_M4eg_SR = reader.readC();
-            sbi_C4eg_SR = reader.readC();
-            sbi_M4wave = reader.readC();
-            sbi_C4wave = reader.readC();
-            sbi_4opConnect = reader.readC();
-            
-            ins->fm.alg = (sbi_FeedConnect & 0x1) | ((sbi_4opConnect & 0x1) << 1);
-            ins->fm.fb = ((sbi_FeedConnect >> 1) & 0x7);
-
-            opM.mult = sbi_Mcharacteristics & 0xF;
-            opM.ksr = ((sbi_Mcharacteristics >> 4) & 0x1);
-            opM.sus = ((sbi_Mcharacteristics >> 5) & 0x1);
-            opM.vib = ((sbi_Mcharacteristics >> 6) & 0x1);
-            opM.am = ((sbi_Mcharacteristics >> 7) & 0x1);
-            opM.tl = sbi_Mscaling_output & 0x3F;
-            opM.ksl = ((sbi_Mscaling_output >> 6) & 0x3);
-            opM.ar = ((sbi_Meg_AD >> 4) & 0xF);
-            opM.dr = (sbi_Meg_AD & 0xF);
-            opM.rr = (sbi_Meg_SR & 0xF);
-            opM.sl = ((sbi_Meg_SR >> 4) & 0xF);
-            opM.ws = sbi_Mwave;
-
-            opC.mult = sbi_Ccharacteristics & 0xF;
-            opC.ksr = ((sbi_Ccharacteristics >> 4) & 0x1);
-            opC.sus = ((sbi_Ccharacteristics >> 5) & 0x1);
-            opC.vib = ((sbi_Ccharacteristics >> 6) & 0x1);
-            opC.am = ((sbi_Ccharacteristics >> 7) & 0x1);
-            opC.tl = sbi_Cscaling_output & 0x3F;
-            opC.ksl = ((sbi_Cscaling_output >> 6) & 0x3);
-            opC.ar = ((sbi_Ceg_AD >> 4) & 0xF);
-            opC.dr = (sbi_Ceg_AD & 0xF);
-            opC.rr = (sbi_Ceg_SR & 0xF);
-            opC.sl = ((sbi_Ceg_SR >> 4) & 0xF);
-            opC.ws = sbi_Cwave;
-            
-            opM4.mult = sbi_M4characteristics & 0xF;
-            opM4.ksr = ((sbi_M4characteristics >> 4) & 0x1);
-            opM4.sus = ((sbi_M4characteristics >> 5) & 0x1);
-            opM4.vib = ((sbi_M4characteristics >> 6) & 0x1);
-            opM4.am = ((sbi_M4characteristics >> 7) & 0x1);
-            opM4.tl = sbi_M4scaling_output & 0x3F;
-            opM4.ksl = ((sbi_M4scaling_output >> 6) & 0x3);
-            opM4.ar = ((sbi_M4eg_AD >> 4) & 0xF);
-            opM4.dr = (sbi_M4eg_AD & 0xF);
-            opM4.rr = (sbi_M4eg_SR & 0xF);
-            opM4.sl = ((sbi_M4eg_SR >> 4) & 0xF);
-            opM4.ws = sbi_M4wave;
-
-            opC4.mult = sbi_C4characteristics & 0xF;
-            opC4.ksr = ((sbi_C4characteristics >> 4) & 0x1);
-            opC4.sus = ((sbi_C4characteristics >> 5) & 0x1);
-            opC4.vib = ((sbi_C4characteristics >> 6) & 0x1);
-            opC4.am = ((sbi_C4characteristics >> 7) & 0x1);
-            opC4.tl = sbi_C4scaling_output & 0x3F;
-            opC4.ksl = ((sbi_C4scaling_output >> 6) & 0x3);
-            opC4.ar = ((sbi_C4eg_AD >> 4) & 0xF);
-            opC4.dr = (sbi_C4eg_AD & 0xF);
-            opC4.rr = (sbi_C4eg_SR & 0xF);
-            opC4.sl = ((sbi_C4eg_SR >> 4) & 0xF);
-            opC4.ws = sbi_C4wave;
-
-            // Ignore rest of file once we've read in all we need.
-            // Note: Freq Monster 801 adds a ton of other additional fields irrelevant to chip registers.
-            reader.seek(0, SEEK_END);
-          }
-
-        } catch (EndOfFileException& e) {
-          lastError = "premature end of file";
-          logE("premature end of file!\n");
-          delete ins;
-          delete[] buf;
-          return ret;
-        }
-        break;
-    }
-
-    if (reader.tell()<reader.size()) {
-      addWarning("https://github.com/tildearrow/furnace/issues/84");
-      addWarning("there is more data at the end of the file! what happened here!");
-      addWarning(fmt::sprintf("exactly %d bytes, if you are curious",reader.size()-reader.tell()));
-    }
-  }
-
-  ret.push_back(ins);
-  return ret;
-}
-
 void DivEngine::delInstrument(int index) {
   BUSY_BEGIN;
   saveLock.lock();
diff --git a/src/engine/fileOpsIns.cpp b/src/engine/fileOpsIns.cpp
new file mode 100644
index 00000000..6b96db59
--- /dev/null
+++ b/src/engine/fileOpsIns.cpp
@@ -0,0 +1,765 @@
+/**
+ * Furnace Tracker - multi-system chiptune tracker
+ * Copyright (C) 2021-2022 tildearrow and contributors
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "engine.h"
+#include "../ta-log.h"
+#include "../fileutils.h"
+#include <fmt/printf.h>
+
+enum DivInsFormats {
+  DIV_INSFORMAT_DMP,
+  DIV_INSFORMAT_TFI,
+  DIV_INSFORMAT_VGI,
+  DIV_INSFORMAT_FTI,
+  DIV_INSFORMAT_BTI,
+  DIV_INSFORMAT_S3I,
+  DIV_INSFORMAT_SBI,
+  DIV_INSFORMAT_OPM
+};
+
+std::vector<DivInstrument*> DivEngine::instrumentFromFile(const char* path) {
+  std::vector<DivInstrument*> ret;
+  warnings="";
+
+  const char* pathRedux=strrchr(path,DIR_SEPARATOR);
+  if (pathRedux==NULL) {
+    pathRedux=path;
+  } else {
+    pathRedux++;
+  }
+  String stripPath;
+  const char* pathReduxEnd=strrchr(pathRedux,'.');
+  if (pathReduxEnd==NULL) {
+    stripPath=pathRedux;
+  } else {
+    for (const char* i=pathRedux; i!=pathReduxEnd && (*i); i++) {
+      stripPath+=*i;
+    }
+  }
+
+  FILE* f=ps_fopen(path,"rb");
+  if (f==NULL) {
+    lastError=strerror(errno);
+    return ret;
+  }
+  unsigned char* buf;
+  ssize_t len;
+  if (fseek(f,0,SEEK_END)!=0) {
+    lastError=strerror(errno);
+    fclose(f);
+    return ret;
+  }
+  len=ftell(f);
+  if (len<0) {
+    lastError=strerror(errno);
+    fclose(f);
+    return ret;
+  }
+  if (len==0) {
+    lastError=strerror(errno);
+    fclose(f);
+    return ret;
+  }
+  if (fseek(f,0,SEEK_SET)!=0) {
+    lastError=strerror(errno);
+    fclose(f);
+    return ret;
+  }
+  buf=new unsigned char[len];
+  if (fread(buf,1,len,f)!=(size_t)len) {
+    logW("did not read entire instrument file buffer!\n");
+    lastError="did not read entire instrument file!";
+    delete[] buf;
+    return ret;
+  }
+  fclose(f);
+
+  SafeReader reader=SafeReader(buf,len);
+
+  unsigned char magic[16];
+  bool isFurnaceInstr=false;
+  try {
+    reader.read(magic,16);
+    if (memcmp("-Furnace instr.-",magic,16)==0) {
+      isFurnaceInstr=true;
+    }
+  } catch (EndOfFileException& e) {
+    reader.seek(0,SEEK_SET);
+  }
+
+  DivInstrument* ins=new DivInstrument;
+  if (isFurnaceInstr) {
+    try {
+      short version=reader.readS();
+      reader.readS(); // reserved
+
+      if (version>DIV_ENGINE_VERSION) {
+        warnings="this instrument is made with a more recent version of Furnace!";
+      }
+
+      unsigned int dataPtr=reader.readI();
+      reader.seek(dataPtr,SEEK_SET);
+
+      if (ins->readInsData(reader,version)!=DIV_DATA_SUCCESS) {
+        lastError="invalid instrument header/data!";
+        delete ins;
+        delete[] buf;
+        return ret;
+      }
+    } catch (EndOfFileException& e) {
+      lastError="premature end of file";
+      logE("premature end of file!\n");
+      delete ins;
+      delete[] buf;
+      return ret;
+    }
+  } else { // read as a different format
+    const char* ext=strrchr(path,'.');
+    DivInsFormats format=DIV_INSFORMAT_DMP;
+    if (ext!=NULL) {
+      String extS;
+      for (; *ext; ext++) {
+        char i=*ext;
+        if (i>='A' && i<='Z') {
+          i+='a'-'A';
+        }
+        extS+=i;
+      }
+      if (extS==String(".dmp")) {
+        format=DIV_INSFORMAT_DMP;
+      } else if (extS==String(".tfi")) {
+        format=DIV_INSFORMAT_TFI;
+      } else if (extS==String(".vgi")) {
+        format=DIV_INSFORMAT_VGI;
+      } else if (extS==String(".fti")) {
+        format=DIV_INSFORMAT_FTI;
+      } else if (extS==String(".bti")) {
+        format=DIV_INSFORMAT_BTI;
+      } else if (extS==String(".s3i")) {
+        format=DIV_INSFORMAT_S3I;
+      } else if (extS==String(".sbi")) {
+        format=DIV_INSFORMAT_SBI;
+      } else if (extS==String(".opm")) {
+        format=DIV_INSFORMAT_OPM;
+      }
+    }
+
+    // TDOO these really should be re-organized to separate functions per instrument file type.
+    switch (format) {
+      case DIV_INSFORMAT_DMP: {
+        // this is a ridiculous mess
+        unsigned char version=0;
+        unsigned char sys=0;
+        try {
+          reader.seek(0,SEEK_SET);
+          version=reader.readC();
+          logD(".dmp version %d\n",version);
+        } catch (EndOfFileException& e) {
+          lastError="premature end of file";
+          logE("premature end of file!\n");
+          delete ins;
+          delete[] buf;
+          return ret;
+        }
+
+        if (version>11) {
+          lastError="unknown instrument version!";
+          delete ins;
+          delete[] buf;
+          return ret;
+        }
+
+        ins->name=stripPath;
+
+        if (version>=11) { // 1.0
+          try {
+            sys=reader.readC();
+      
+            switch (sys) {
+              case 1: // YMU759
+                ins->type=DIV_INS_FM;
+                logD("instrument type is YMU759\n");
+                break;
+              case 2: // Genesis
+                ins->type=DIV_INS_FM;
+                logD("instrument type is Genesis\n");
+                break;
+              case 3: // SMS
+                ins->type=DIV_INS_STD;
+                logD("instrument type is SMS\n");
+                break;
+              case 4: // Game Boy
+                ins->type=DIV_INS_GB;
+                logD("instrument type is Game Boy\n");
+                break;
+              case 5: // PC Engine
+                ins->type=DIV_INS_PCE;
+                logD("instrument type is PC Engine\n");
+                break;
+              case 6: // NES
+                ins->type=DIV_INS_STD;
+                logD("instrument type is NES\n");
+                break;
+              case 7: case 0x17: // C64
+                ins->type=DIV_INS_C64;
+                logD("instrument type is C64\n");
+                break;
+              case 8: // Arcade
+                ins->type=DIV_INS_FM;
+                logD("instrument type is Arcade\n");
+                break;
+              default:
+                logD("instrument type is unknown\n");
+                lastError="unknown instrument type!";
+                delete ins;
+                delete[] buf;
+                return ret;
+                break;
+            }
+          } catch (EndOfFileException& e) {
+            lastError="premature end of file";
+            logE("premature end of file!\n");
+            delete ins;
+            delete[] buf;
+            return ret;
+          }
+        }
+
+        try {
+          bool mode=true;
+          if (version>1) {
+            mode=reader.readC();
+            logD("instrument mode is %d\n",mode);
+            if (mode==0) {
+              if (version<11) {
+                ins->type=DIV_INS_STD;
+              }
+            } else {
+              ins->type=DIV_INS_FM;
+            }
+          } else {
+            ins->type=DIV_INS_FM;
+          }
+
+          if (mode) { // FM
+            logD("reading FM data...\n");
+            if (version<10) {
+              if (version>1) {
+                ins->fm.ops=reader.readC()?4:2;
+              } else {
+                ins->fm.ops=reader.readC()?2:4;
+              }
+            } else {
+              ins->fm.ops=4;
+            }
+            if (version>1) { // HELP! in which version of the format did we start storing FMS!
+              ins->fm.fms=reader.readC();
+            }
+            ins->fm.fb=reader.readC();
+            ins->fm.alg=reader.readC();
+            // DITTO
+            if (sys!=1) ins->fm.ams=reader.readC();
+
+            for (int j=0; j<ins->fm.ops; j++) {
+              logD("OP%d is at %d\n",j,reader.tell());
+              ins->fm.op[j].mult=reader.readC();
+              ins->fm.op[j].tl=reader.readC();
+              ins->fm.op[j].ar=reader.readC();
+              ins->fm.op[j].dr=reader.readC();
+              ins->fm.op[j].sl=reader.readC();
+              ins->fm.op[j].rr=reader.readC();
+              ins->fm.op[j].am=reader.readC();
+              // what the hell how do I tell!
+              if (sys==1) { // YMU759
+                ins->fm.op[j].ws=reader.readC();
+                ins->fm.op[j].ksl=reader.readC();
+                ins->fm.op[j].vib=reader.readC();
+                ins->fm.op[j].egt=reader.readC();
+                ins->fm.op[j].sus=reader.readC();
+                ins->fm.op[j].ksr=reader.readC();
+                ins->fm.op[j].dvb=reader.readC();
+                ins->fm.op[j].dam=reader.readC();
+              } else {
+                ins->fm.op[j].rs=reader.readC();
+                ins->fm.op[j].dt=reader.readC();
+                ins->fm.op[j].dt2=ins->fm.op[j].dt>>4;
+                ins->fm.op[j].dt&=15;
+                ins->fm.op[j].d2r=reader.readC();
+                ins->fm.op[j].ssgEnv=reader.readC();
+              }
+            }
+          } else { // STD
+            logD("reading STD data...\n");
+            if (ins->type!=DIV_INS_GB) {
+              ins->std.volMacroLen=reader.readC();
+              if (version>5) {
+                for (int i=0; i<ins->std.volMacroLen; i++) {
+                  ins->std.volMacro[i]=reader.readI();
+                }
+              } else {
+                for (int i=0; i<ins->std.volMacroLen; i++) {
+                  ins->std.volMacro[i]=reader.readC();
+                }
+              }
+              if (version<11) for (int i=0; i<ins->std.volMacroLen; i++) {
+                if (ins->std.volMacro[i]>15 && ins->type==DIV_INS_STD) ins->type=DIV_INS_PCE;
+              }
+              if (ins->std.volMacroLen>0) {
+                ins->std.volMacroOpen=true;
+                ins->std.volMacroLoop=reader.readC();
+              } else {
+                ins->std.volMacroOpen=false;
+              }
+            }
+
+            ins->std.arpMacroLen=reader.readC();
+            if (version>5) {
+              for (int i=0; i<ins->std.arpMacroLen; i++) {
+                ins->std.arpMacro[i]=reader.readI();
+              }
+            } else {
+              for (int i=0; i<ins->std.arpMacroLen; i++) {
+                ins->std.arpMacro[i]=reader.readC();
+              }
+            }
+            if (ins->std.arpMacroLen>0) {
+              ins->std.arpMacroOpen=true;
+              ins->std.arpMacroLoop=reader.readC();
+            } else {
+              ins->std.arpMacroOpen=false;
+            }
+            if (version>8) { // TODO: when?
+              ins->std.arpMacroMode=reader.readC();
+            }
+
+            ins->std.dutyMacroLen=reader.readC();
+            if (version>5) {
+              for (int i=0; i<ins->std.dutyMacroLen; i++) {
+                ins->std.dutyMacro[i]=reader.readI();
+              }
+            } else {
+              for (int i=0; i<ins->std.dutyMacroLen; i++) {
+                ins->std.dutyMacro[i]=reader.readC();
+              }
+            }
+            if (ins->std.dutyMacroLen>0) {
+              ins->std.dutyMacroOpen=true;
+              ins->std.dutyMacroLoop=reader.readC();
+            } else {
+              ins->std.dutyMacroOpen=false;
+            }
+
+            ins->std.waveMacroLen=reader.readC();
+            if (version>5) {
+              for (int i=0; i<ins->std.waveMacroLen; i++) {
+                ins->std.waveMacro[i]=reader.readI();
+              }
+            } else {
+              for (int i=0; i<ins->std.waveMacroLen; i++) {
+                ins->std.waveMacro[i]=reader.readC();
+              }
+            }
+            if (ins->std.waveMacroLen>0) {
+              ins->std.waveMacroOpen=true;
+              ins->std.waveMacroLoop=reader.readC();
+            } else {
+              ins->std.waveMacroOpen=false;
+            }
+
+            if (ins->type==DIV_INS_C64) {
+              ins->c64.triOn=reader.readC();
+              ins->c64.sawOn=reader.readC();
+              ins->c64.pulseOn=reader.readC();
+              ins->c64.noiseOn=reader.readC();
+
+              ins->c64.a=reader.readC();
+              ins->c64.d=reader.readC();
+              ins->c64.s=reader.readC();
+              ins->c64.r=reader.readC();
+
+              ins->c64.duty=(reader.readC()*4095)/100;
+
+              ins->c64.ringMod=reader.readC();
+              ins->c64.oscSync=reader.readC();
+              ins->c64.toFilter=reader.readC();
+              if (version<0x07) { // TODO: UNSURE
+                ins->c64.volIsCutoff=reader.readI();
+              } else {
+                ins->c64.volIsCutoff=reader.readC();
+              }
+              ins->c64.initFilter=reader.readC();
+
+              ins->c64.res=reader.readC();
+              ins->c64.cut=(reader.readC()*2047)/100;
+              ins->c64.hp=reader.readC();
+              ins->c64.bp=reader.readC();
+              ins->c64.lp=reader.readC();
+              ins->c64.ch3off=reader.readC();
+            }
+            if (ins->type==DIV_INS_GB) {
+              ins->gb.envVol=reader.readC();
+              ins->gb.envDir=reader.readC();
+              ins->gb.envLen=reader.readC();
+              ins->gb.soundLen=reader.readC();
+            }
+          }
+        } catch (EndOfFileException& e) {
+          lastError="premature end of file";
+          logE("premature end of file!\n");
+          delete ins;
+          delete[] buf;
+          return ret;
+        }
+        break;
+      }
+      case DIV_INSFORMAT_TFI:
+        try {
+          reader.seek(0,SEEK_SET);
+
+          ins->type=DIV_INS_FM;
+          ins->name=stripPath;
+          
+          ins->fm.alg=reader.readC();
+          ins->fm.fb=reader.readC();
+
+          for (int i=0; i<4; i++) {
+            DivInstrumentFM::Operator& op=ins->fm.op[i];
+
+            op.mult=reader.readC();
+            op.dt=reader.readC();
+            op.tl=reader.readC();
+            op.rs=reader.readC();
+            op.ar=reader.readC();
+            op.dr=reader.readC();
+            op.d2r=reader.readC();
+            op.rr=reader.readC();
+            op.sl=reader.readC();
+            op.ssgEnv=reader.readC();
+          }
+        } catch (EndOfFileException& e) {
+          lastError="premature end of file";
+          logE("premature end of file!\n");
+          delete ins;
+          delete[] buf;
+          return ret;
+        }
+        break;
+      case DIV_INSFORMAT_VGI:
+        try {
+          reader.seek(0,SEEK_SET);
+
+          ins->type=DIV_INS_FM;
+          ins->name=stripPath;
+          
+          ins->fm.alg=reader.readC();
+          ins->fm.fb=reader.readC();
+          unsigned char fmsams=reader.readC();
+          ins->fm.fms=fmsams&7;
+          ins->fm.ams=fmsams>>4;
+
+          for (int i=0; i<4; i++) {
+            DivInstrumentFM::Operator& op=ins->fm.op[i];
+
+            op.mult=reader.readC();
+            op.dt=reader.readC();
+            op.tl=reader.readC();
+            op.rs=reader.readC();
+            op.ar=reader.readC();
+            op.dr=reader.readC();
+            if (op.dr&0x80) {
+              op.am=1;
+              op.dr&=0x7f;
+            }
+            op.d2r=reader.readC();
+            op.rr=reader.readC();
+            op.sl=reader.readC();
+            op.ssgEnv=reader.readC();
+          }
+        } catch (EndOfFileException& e) {
+          lastError="premature end of file";
+          logE("premature end of file!\n");
+          delete ins;
+          delete[] buf;
+          return ret;
+        }
+        break;
+      case DIV_INSFORMAT_FTI: // TODO
+        break;
+      case DIV_INSFORMAT_BTI: // TODO
+        break;
+      case DIV_INSFORMAT_OPM: // TODO
+        break;
+      case DIV_INSFORMAT_S3I:
+        try {
+          reader.seek(0, SEEK_SET);
+
+          uint8_t s3i_type = reader.readC();
+
+          if (s3i_type >= 2) {
+            ins->type = DIV_INS_OPL;
+            // skip internal filename - we'll use the long name description
+            reader.seek(12, SEEK_CUR);
+
+            // skip reserved bytes
+            reader.seek(3, SEEK_CUR);
+
+            // 12-byte opl value
+            uint8_t s3i_Mcharacteristics = reader.readC();
+            uint8_t s3i_Ccharacteristics = reader.readC();
+            uint8_t s3i_Mscaling_output = reader.readC();
+            uint8_t s3i_Cscaling_output = reader.readC();
+            uint8_t s3i_Meg_AD = reader.readC();
+            uint8_t s3i_Ceg_AD = reader.readC();
+            uint8_t s3i_Meg_SR = reader.readC();
+            uint8_t s3i_Ceg_SR = reader.readC();
+            uint8_t s3i_Mwave = reader.readC();
+            uint8_t s3i_Cwave = reader.readC();
+            uint8_t s3i_FeedConnect = reader.readC();
+            
+            DivInstrumentFM::Operator& opM = ins->fm.op[0];
+            DivInstrumentFM::Operator& opC = ins->fm.op[1];
+            ins->fm.ops = 2;
+            opM.mult = s3i_Mcharacteristics & 0xF;
+            opM.ksr = ((s3i_Mcharacteristics >> 4) & 0x1);
+            opM.sus = ((s3i_Mcharacteristics >> 5) & 0x1);
+            opM.vib = ((s3i_Mcharacteristics >> 6) & 0x1);
+            opM.am = ((s3i_Mcharacteristics >> 7) & 0x1);
+            opM.tl = s3i_Mscaling_output & 0x3F;
+            opM.ksl = ((s3i_Mscaling_output >> 6) & 0x3);
+            opM.ar = ((s3i_Meg_AD >> 4) & 0xF);
+            opM.dr = (s3i_Meg_AD & 0xF);
+            opM.rr = (s3i_Meg_SR & 0xF);
+            opM.sl = ((s3i_Meg_SR >> 4) & 0xF);
+            opM.ws = s3i_Mwave;
+
+            ins->fm.alg = (s3i_FeedConnect & 0x1);
+            ins->fm.fb = ((s3i_FeedConnect >> 1) & 0x7);
+
+            opC.mult = s3i_Ccharacteristics & 0xF;
+            opC.ksr = ((s3i_Ccharacteristics >> 4) & 0x1);
+            opC.sus = ((s3i_Ccharacteristics >> 5) & 0x1);
+            opC.vib = ((s3i_Ccharacteristics >> 6) & 0x1);
+            opC.am = ((s3i_Ccharacteristics >> 7) & 0x1);
+            opC.tl = s3i_Cscaling_output & 0x3F;
+            opC.ksl = ((s3i_Cscaling_output >> 6) & 0x3);
+            opC.ar = ((s3i_Ceg_AD >> 4) & 0xF);
+            opC.dr = (s3i_Ceg_AD & 0xF);
+            opC.rr = (s3i_Ceg_SR & 0xF);
+            opC.sl = ((s3i_Ceg_SR >> 4) & 0xF);
+            opC.ws = s3i_Cwave;
+
+            // Skip more stuff we don't need
+            reader.seek(21, SEEK_CUR);
+          } else {
+            logE("S3I PCM samples currently not supported.");
+          }
+          ins->name = reader.readString(28);
+          int s3i_signature = reader.readI();
+
+          if (s3i_signature != 0x49524353) {
+            logW("S3I signature invalid.");
+          };
+        }
+        catch (EndOfFileException& e) {
+          lastError = "premature end of file";
+          logE("premature end of file!\n");
+          delete ins;
+          delete[] buf;
+          return ret;
+        }
+        break;
+      case DIV_INSFORMAT_SBI:
+        try {
+          reader.seek(0, SEEK_SET);
+          ins->type = DIV_INS_OPL;
+
+          int sbi_header = reader.readI();
+          // SBI header determines format
+          bool is_2op = (sbi_header == 0x1A494253); // SBI\x1A
+          bool is_4op = (sbi_header == 0x1A504F34); // 4OP\x1A
+          bool is_6op = (sbi_header == 0x1A504F36); // 6OP\x1A - Freq Monster 801-specific
+
+          // 32-byte null terminated instrument name
+          ins->name = reader.readString(32);
+
+          // 2op SBI
+          uint8_t sbi_Mcharacteristics = reader.readC();
+          uint8_t sbi_Ccharacteristics = reader.readC();
+          uint8_t sbi_Mscaling_output = reader.readC();
+          uint8_t sbi_Cscaling_output = reader.readC();
+          uint8_t sbi_Meg_AD = reader.readC();
+          uint8_t sbi_Ceg_AD = reader.readC();
+          uint8_t sbi_Meg_SR = reader.readC();
+          uint8_t sbi_Ceg_SR = reader.readC();
+          uint8_t sbi_Mwave = reader.readC();
+          uint8_t sbi_Cwave = reader.readC();
+          uint8_t sbi_FeedConnect = reader.readC();
+
+          // 4op SBI
+          uint8_t sbi_M4characteristics;
+          uint8_t sbi_C4characteristics;
+          uint8_t sbi_M4scaling_output;
+          uint8_t sbi_C4scaling_output;
+          uint8_t sbi_M4eg_AD;
+          uint8_t sbi_C4eg_AD;
+          uint8_t sbi_M4eg_SR;
+          uint8_t sbi_C4eg_SR;
+          uint8_t sbi_M4wave;
+          uint8_t sbi_C4wave;
+          uint8_t sbi_4opConnect;
+          
+          if (is_2op) {
+            DivInstrumentFM::Operator& opM = ins->fm.op[0];
+            DivInstrumentFM::Operator& opC = ins->fm.op[1];
+            ins->fm.ops = 2;
+            opM.mult = sbi_Mcharacteristics & 0xF;
+            opM.ksr = ((sbi_Mcharacteristics >> 4) & 0x1);
+            opM.sus = ((sbi_Mcharacteristics >> 5) & 0x1);
+            opM.vib = ((sbi_Mcharacteristics >> 6) & 0x1);
+            opM.am = ((sbi_Mcharacteristics >> 7) & 0x1);
+            opM.tl = sbi_Mscaling_output & 0x3F;
+            opM.ksl = ((sbi_Mscaling_output >> 6) & 0x3);
+            opM.ar = ((sbi_Meg_AD >> 4) & 0xF);
+            opM.dr = (sbi_Meg_AD & 0xF);
+            opM.rr = (sbi_Meg_SR & 0xF);
+            opM.sl = ((sbi_Meg_SR >> 4) & 0xF);
+            opM.ws = sbi_Mwave;
+
+            ins->fm.alg = (sbi_FeedConnect & 0x1);
+            ins->fm.fb = ((sbi_FeedConnect >> 1) & 0x7);
+
+            opC.mult = sbi_Ccharacteristics & 0xF;
+            opC.ksr = ((sbi_Ccharacteristics >> 4) & 0x1);
+            opC.sus = ((sbi_Ccharacteristics >> 5) & 0x1);
+            opC.vib = ((sbi_Ccharacteristics >> 6) & 0x1);
+            opC.am = ((sbi_Ccharacteristics >> 7) & 0x1);
+            opC.tl = sbi_Cscaling_output & 0x3F;
+            opC.ksl = ((sbi_Cscaling_output >> 6) & 0x3);
+            opC.ar = ((sbi_Ceg_AD >> 4) & 0xF);
+            opC.dr = (sbi_Ceg_AD & 0xF);
+            opC.rr = (sbi_Ceg_SR & 0xF);
+            opC.sl = ((sbi_Ceg_SR >> 4) & 0xF);
+            opC.ws = sbi_Cwave;
+
+            // Ignore rest of file - rest is 'reserved padding'.
+            reader.seek(0, SEEK_END);
+          }
+
+          if (is_4op || is_6op) {
+            // Operator placement is different so need to place in correct registers.
+            // Note: 6op is an unofficial extension of 4op SBIs by Darron Broad (Freq Monster 801).
+            // We'll only use the 4op portion here for pure OPL3.
+            DivInstrumentFM::Operator& opM = ins->fm.op[0];
+            DivInstrumentFM::Operator& opC = ins->fm.op[2];
+            DivInstrumentFM::Operator& opM4 = ins->fm.op[1];
+            DivInstrumentFM::Operator& opC4 = ins->fm.op[3];
+            ins->fm.ops = 4;
+
+            sbi_M4characteristics = reader.readC();
+            sbi_C4characteristics = reader.readC();
+            sbi_M4scaling_output = reader.readC();
+            sbi_C4scaling_output = reader.readC();
+            sbi_M4eg_AD = reader.readC();
+            sbi_C4eg_AD = reader.readC();
+            sbi_M4eg_SR = reader.readC();
+            sbi_C4eg_SR = reader.readC();
+            sbi_M4wave = reader.readC();
+            sbi_C4wave = reader.readC();
+            sbi_4opConnect = reader.readC();
+            
+            ins->fm.alg = (sbi_FeedConnect & 0x1) | ((sbi_4opConnect & 0x1) << 1);
+            ins->fm.fb = ((sbi_FeedConnect >> 1) & 0x7);
+
+            opM.mult = sbi_Mcharacteristics & 0xF;
+            opM.ksr = ((sbi_Mcharacteristics >> 4) & 0x1);
+            opM.sus = ((sbi_Mcharacteristics >> 5) & 0x1);
+            opM.vib = ((sbi_Mcharacteristics >> 6) & 0x1);
+            opM.am = ((sbi_Mcharacteristics >> 7) & 0x1);
+            opM.tl = sbi_Mscaling_output & 0x3F;
+            opM.ksl = ((sbi_Mscaling_output >> 6) & 0x3);
+            opM.ar = ((sbi_Meg_AD >> 4) & 0xF);
+            opM.dr = (sbi_Meg_AD & 0xF);
+            opM.rr = (sbi_Meg_SR & 0xF);
+            opM.sl = ((sbi_Meg_SR >> 4) & 0xF);
+            opM.ws = sbi_Mwave;
+
+            opC.mult = sbi_Ccharacteristics & 0xF;
+            opC.ksr = ((sbi_Ccharacteristics >> 4) & 0x1);
+            opC.sus = ((sbi_Ccharacteristics >> 5) & 0x1);
+            opC.vib = ((sbi_Ccharacteristics >> 6) & 0x1);
+            opC.am = ((sbi_Ccharacteristics >> 7) & 0x1);
+            opC.tl = sbi_Cscaling_output & 0x3F;
+            opC.ksl = ((sbi_Cscaling_output >> 6) & 0x3);
+            opC.ar = ((sbi_Ceg_AD >> 4) & 0xF);
+            opC.dr = (sbi_Ceg_AD & 0xF);
+            opC.rr = (sbi_Ceg_SR & 0xF);
+            opC.sl = ((sbi_Ceg_SR >> 4) & 0xF);
+            opC.ws = sbi_Cwave;
+            
+            opM4.mult = sbi_M4characteristics & 0xF;
+            opM4.ksr = ((sbi_M4characteristics >> 4) & 0x1);
+            opM4.sus = ((sbi_M4characteristics >> 5) & 0x1);
+            opM4.vib = ((sbi_M4characteristics >> 6) & 0x1);
+            opM4.am = ((sbi_M4characteristics >> 7) & 0x1);
+            opM4.tl = sbi_M4scaling_output & 0x3F;
+            opM4.ksl = ((sbi_M4scaling_output >> 6) & 0x3);
+            opM4.ar = ((sbi_M4eg_AD >> 4) & 0xF);
+            opM4.dr = (sbi_M4eg_AD & 0xF);
+            opM4.rr = (sbi_M4eg_SR & 0xF);
+            opM4.sl = ((sbi_M4eg_SR >> 4) & 0xF);
+            opM4.ws = sbi_M4wave;
+
+            opC4.mult = sbi_C4characteristics & 0xF;
+            opC4.ksr = ((sbi_C4characteristics >> 4) & 0x1);
+            opC4.sus = ((sbi_C4characteristics >> 5) & 0x1);
+            opC4.vib = ((sbi_C4characteristics >> 6) & 0x1);
+            opC4.am = ((sbi_C4characteristics >> 7) & 0x1);
+            opC4.tl = sbi_C4scaling_output & 0x3F;
+            opC4.ksl = ((sbi_C4scaling_output >> 6) & 0x3);
+            opC4.ar = ((sbi_C4eg_AD >> 4) & 0xF);
+            opC4.dr = (sbi_C4eg_AD & 0xF);
+            opC4.rr = (sbi_C4eg_SR & 0xF);
+            opC4.sl = ((sbi_C4eg_SR >> 4) & 0xF);
+            opC4.ws = sbi_C4wave;
+
+            // Ignore rest of file once we've read in all we need.
+            // Note: Freq Monster 801 adds a ton of other additional fields irrelevant to chip registers.
+            reader.seek(0, SEEK_END);
+          }
+
+        } catch (EndOfFileException& e) {
+          lastError = "premature end of file";
+          logE("premature end of file!\n");
+          delete ins;
+          delete[] buf;
+          return ret;
+        }
+        break;
+    }
+
+    if (reader.tell()<reader.size()) {
+      addWarning("https://github.com/tildearrow/furnace/issues/84");
+      addWarning("there is more data at the end of the file! what happened here!");
+      addWarning(fmt::sprintf("exactly %d bytes, if you are curious",reader.size()-reader.tell()));
+    }
+  }
+
+  ret.push_back(ins);
+  return ret;
+}
\ No newline at end of file