diff --git a/src/engine/engine.h b/src/engine/engine.h
index 394639505..f4c46de32 100644
--- a/src/engine/engine.h
+++ b/src/engine/engine.h
@@ -54,8 +54,8 @@ class DivWorkPool;
 
 #define DIV_UNSTABLE
 
-#define DIV_VERSION "dev185"
-#define DIV_ENGINE_VERSION 185
+#define DIV_VERSION "dev186"
+#define DIV_ENGINE_VERSION 186
 // for imports
 #define DIV_VERSION_MOD 0xff01
 #define DIV_VERSION_FC 0xff02
diff --git a/src/engine/fileOps.cpp b/src/engine/fileOps.cpp
index 78b79cb5b..0175c02e2 100644
--- a/src/engine/fileOps.cpp
+++ b/src/engine/fileOps.cpp
@@ -3008,6 +3008,15 @@ bool DivEngine::loadFur(unsigned char* file, size_t len) {
       }
     }
 
+    // C64 1Exy compat
+    if (ds.version<186) {
+      for (int i=0; i<ds.systemLen; i++) {
+        if (ds.system[i]==DIV_SYSTEM_C64_8580 || ds.system[i]==DIV_SYSTEM_C64_6581) {
+          ds.systemFlags[i].set("no1EUpdate",true);
+        }
+      }
+    }
+
     if (active) quitDispatch();
     BUSY_BEGIN_SOFT;
     saveLock.lock();
diff --git a/src/engine/platform/c64.cpp b/src/engine/platform/c64.cpp
index 15ff00d92..a7e2e3e03 100644
--- a/src/engine/platform/c64.cpp
+++ b/src/engine/platform/c64.cpp
@@ -457,15 +457,27 @@ int DivPlatformC64::dispatch(DivCommand c) {
       switch (c.value>>4) {
         case 0:
           chan[c.chan].attack=c.value&15;
+          if (!no1EUpdate) {
+            rWrite(c.chan*7+5,(chan[c.chan].attack<<4)|(chan[c.chan].decay));
+          }
           break;
         case 1:
           chan[c.chan].decay=c.value&15;
+          if (!no1EUpdate) {
+            rWrite(c.chan*7+5,(chan[c.chan].attack<<4)|(chan[c.chan].decay));
+          }
           break;
         case 2:
           chan[c.chan].sustain=c.value&15;
+          if (!no1EUpdate) {
+            rWrite(c.chan*7+6,(chan[c.chan].sustain<<4)|(chan[c.chan].release));
+          }
           break;
         case 3:
           chan[c.chan].release=c.value&15;
+          if (!no1EUpdate) {
+            rWrite(c.chan*7+6,(chan[c.chan].sustain<<4)|(chan[c.chan].release));
+          }
           break;
         case 4:
           chan[c.chan].ring=c.value;
@@ -652,6 +664,7 @@ void DivPlatformC64::setFlags(const DivConfig& flags) {
     if (sidCore==1) sid_fp->setSamplingParameters(chipClock,reSIDfp::DECIMATE,rate,0);
   }
   keyPriority=flags.getBool("keyPriority",true);
+  no1EUpdate=flags.getBool("no1EUpdate",false);
   testAD=((flags.getInt("testAttack",0)&15)<<4)|(flags.getInt("testDecay",0)&15);
   testSR=((flags.getInt("testSustain",0)&15)<<4)|(flags.getInt("testRelease",0)&15);
 
diff --git a/src/engine/platform/c64.h b/src/engine/platform/c64.h
index 38e735d9a..67ead6aa7 100644
--- a/src/engine/platform/c64.h
+++ b/src/engine/platform/c64.h
@@ -72,7 +72,7 @@ class DivPlatformC64: public DivDispatch {
   unsigned char sidCore;
   int filtCut, resetTime;
 
-  bool keyPriority, sidIs6581, needInitTables;
+  bool keyPriority, sidIs6581, needInitTables, no1EUpdate;
   unsigned char chanOrder[3];
   unsigned char testAD, testSR;
 
diff --git a/src/gui/sysConf.cpp b/src/gui/sysConf.cpp
index b8caa7390..19a42a877 100644
--- a/src/gui/sysConf.cpp
+++ b/src/gui/sysConf.cpp
@@ -586,6 +586,7 @@ bool FurnaceGUI::drawSysConf(int chan, int sysPos, DivSystem type, DivConfig& fl
     case DIV_SYSTEM_C64_6581: {
       int clockSel=flags.getInt("clockSel",0);
       bool keyPriority=flags.getBool("keyPriority",true);
+      bool no1EUpdate=flags.getBool("no1EUpdate",false);
       int testAttack=flags.getInt("testAttack",0);
       int testDecay=flags.getInt("testDecay",0);
       int testSustain=flags.getInt("testSustain",0);
@@ -644,10 +645,15 @@ bool FurnaceGUI::drawSysConf(int chan, int sysPos, DivSystem type, DivConfig& fl
         altered=true;
       }
 
+      if (ImGui::Checkbox("Disable 1Exy env ipdate (compatibility)",&no1EUpdate)) {
+        altered=true;
+      }
+
       if (altered) {
         e->lockSave([&]() {
           flags.set("clockSel",clockSel);
           flags.set("keyPriority",keyPriority);
+          flags.set("no1EUpdate",no1EUpdate);
           flags.set("testAttack",testAttack);
           flags.set("testDecay",testDecay);
           flags.set("testSustain",testSustain);