diff --git a/UI.hpp b/UI.hpp
index 0a0ec8d..5ae21a1 100644
--- a/UI.hpp
+++ b/UI.hpp
@@ -158,6 +158,13 @@ void UI_func_bc_range(uint8_t param);
 void UI_func_bc_assign(uint8_t param);
 void UI_func_at_range(uint8_t param);
 void UI_func_at_assign(uint8_t param);
+void UI_func_OP1(uint8_t param);
+void UI_func_OP2(uint8_t param);
+void UI_func_OP3(uint8_t param);
+void UI_func_OP4(uint8_t param);
+void UI_func_OP5(uint8_t param);
+void UI_func_OP6(uint8_t param);
+void UI_handle_OP(uint8_t param, uint8_t op, uint8_t instance_id);
 void UI_func_information(uint8_t param);
 void UI_func_voice_selection(uint8_t param);
 void UI_func_volume(uint8_t param);
@@ -204,12 +211,12 @@ LCDML_add(28, LCDML_0_1_2_12, 1, "Port. Mode 1", UI_function_not_enabled);
 LCDML_add(29, LCDML_0_1_2_12, 2, "Port. Gliss 1", UI_function_not_enabled);
 LCDML_add(30, LCDML_0_1_2_12, 3, "Port. Time 1", UI_function_not_enabled);
 LCDML_add(31, LCDML_0_1_2, 16, "Operator 1", NULL);
-LCDML_add(32, LCDML_0_1_2_13, 1, "OP1 1", UI_function_not_implemented);
-LCDML_add(33, LCDML_0_1_2_13, 2, "OP2 1", UI_function_not_implemented);
-LCDML_add(34, LCDML_0_1_2_13, 3, "OP3 1", UI_function_not_implemented);
-LCDML_add(35, LCDML_0_1_2_13, 4, "OP4 1", UI_function_not_implemented);
-LCDML_add(36, LCDML_0_1_2_13, 5, "OP5 1", UI_function_not_implemented);
-LCDML_add(37, LCDML_0_1_2_13, 6, "OP6 1", UI_function_not_implemented);
+LCDML_add(32, LCDML_0_1_2_13, 1, "OP1 1", UI_func_OP1);
+LCDML_add(33, LCDML_0_1_2_13, 2, "OP2 1", UI_func_OP2);
+LCDML_add(34, LCDML_0_1_2_13, 3, "OP3 1", UI_func_OP3);
+LCDML_add(35, LCDML_0_1_2_13, 4, "OP4 1", UI_func_OP4);
+LCDML_add(36, LCDML_0_1_2_13, 5, "OP5 1", UI_func_OP5);
+LCDML_add(37, LCDML_0_1_2_13, 6, "OP6 1", UI_func_OP6);
 LCDML_add(38, LCDML_0_1, 3, "Instance 2", NULL);
 LCDML_add(39, LCDML_0_1_3, 1, "MIDI Channel 2", UI_func_midi_channel);
 LCDML_add(40, LCDML_0_1_3, 2, "Loudness 2", UI_func_loudness);
@@ -240,12 +247,12 @@ LCDML_add(64, LCDML_0_1_3_12, 1, "Port. Mode 2", UI_function_not_enabled);
 LCDML_add(65, LCDML_0_1_3_12, 2, "Port. Gliss 2", UI_function_not_enabled);
 LCDML_add(66, LCDML_0_1_3_12, 3, "Port. Time 2", UI_function_not_enabled);
 LCDML_add(67, LCDML_0_1_3, 16, "Operator 2", NULL);
-LCDML_add(68, LCDML_0_1_3_13, 1, "OP1 2", UI_function_not_implemented);
-LCDML_add(69, LCDML_0_1_3_13, 2, "OP2 2", UI_function_not_implemented);
-LCDML_add(70, LCDML_0_1_3_13, 3, "OP3 2", UI_function_not_implemented);
-LCDML_add(71, LCDML_0_1_3_13, 4, "OP4 2", UI_function_not_implemented);
-LCDML_add(72, LCDML_0_1_3_13, 5, "OP5 2", UI_function_not_implemented);
-LCDML_add(73, LCDML_0_1_3_13, 6, "OP6 2", UI_function_not_implemented);
+LCDML_add(68, LCDML_0_1_3_13, 1, "OP1 2", UI_func_OP1);
+LCDML_add(69, LCDML_0_1_3_13, 2, "OP2 2", UI_func_OP2);
+LCDML_add(70, LCDML_0_1_3_13, 3, "OP3 2", UI_func_OP3);
+LCDML_add(71, LCDML_0_1_3_13, 4, "OP4 2", UI_func_OP4);
+LCDML_add(72, LCDML_0_1_3_13, 5, "OP5 2", UI_func_OP5);
+LCDML_add(73, LCDML_0_1_3_13, 6, "OP6 2", UI_func_OP6);
 LCDML_add(74, LCDML_0, 2, "Effect", NULL);
 LCDML_add(75, LCDML_0_2, 1, "Reverb", NULL);
 LCDML_add(76, LCDML_0_2_1, 1, "Roomsize", UI_func_reverb_roomsize);
@@ -297,12 +304,12 @@ LCDML_add(26, LCDML_0_1_15, 1, "Port. Mode", UI_function_not_implemented);
 LCDML_add(27, LCDML_0_1_15, 2, "Port. Gliss", UI_function_not_implemented);
 LCDML_add(28, LCDML_0_1_15, 3, "Port. Time", UI_function_not_implemented);
 LCDML_add(29, LCDML_0_1, 16, "Operator", NULL);
-LCDML_add(30, LCDML_0_1_16, 1, "OP1", UI_function_not_implemented);
-LCDML_add(31, LCDML_0_1_16, 2, "OP2", UI_function_not_implemented);
-LCDML_add(32, LCDML_0_1_16, 3, "OP3", UI_function_not_implemented);
-LCDML_add(33, LCDML_0_1_16, 4, "OP4", UI_function_not_implemented);
-LCDML_add(34, LCDML_0_1_16, 5, "OP5", UI_function_not_implemented);
-LCDML_add(35, LCDML_0_1_16, 6, "OP6", UI_function_not_implemented);
+LCDML_add(30, LCDML_0_1_16, 1, "OP1", UI_func_OP1);
+LCDML_add(31, LCDML_0_1_16, 2, "OP2", UI_func_OP2);
+LCDML_add(32, LCDML_0_1_16, 3, "OP3", UI_func_OP3);
+LCDML_add(33, LCDML_0_1_16, 4, "OP4", UI_func_OP4);
+LCDML_add(34, LCDML_0_1_16, 5, "OP5", UI_func_OP5);
+LCDML_add(35, LCDML_0_1_16, 6, "OP6", UI_func_OP6);
 LCDML_add(36, LCDML_0, 2, "Effect", NULL);
 LCDML_add(37, LCDML_0_2, 1, "Reverb", NULL);
 LCDML_add(38, LCDML_0_2_1, 1, "Roomsize", UI_func_reverb_roomsize);
@@ -2483,6 +2490,109 @@ void UI_func_at_assign(uint8_t param)
   }
 }
 
+void UI_func_OP1(uint8_t param)
+{
+  uint8_t instance_id = 0;
+
+  if (LCDML.FUNC_getID() > MENU_ID_OF_INSTANCE_2)
+    instance_id = 1;
+
+  UI_handle_OP(param, 0, instance_id);
+}
+
+void UI_func_OP2(uint8_t param)
+{
+  uint8_t instance_id = 0;
+
+  if (LCDML.FUNC_getID() > MENU_ID_OF_INSTANCE_2)
+    instance_id = 1;
+
+  UI_handle_OP(param, 0, instance_id);
+}
+
+void UI_func_OP3(uint8_t param)
+{
+  uint8_t instance_id = 0;
+
+  if (LCDML.FUNC_getID() > MENU_ID_OF_INSTANCE_2)
+    instance_id = 1;
+
+  UI_handle_OP(param, 2, instance_id);
+}
+
+void UI_func_OP4(uint8_t param)
+{
+  uint8_t instance_id = 0;
+
+  if (LCDML.FUNC_getID() > MENU_ID_OF_INSTANCE_2)
+    instance_id = 1;
+
+  UI_handle_OP(param, 3, instance_id);
+}
+
+void UI_func_OP5(uint8_t param)
+{
+  uint8_t instance_id = 0;
+
+  if (LCDML.FUNC_getID() > MENU_ID_OF_INSTANCE_2)
+    instance_id = 1;
+
+  UI_handle_OP(param, 4, instance_id);
+}
+
+void UI_func_OP6(uint8_t param)
+{
+  uint8_t instance_id = 0;
+
+  if (LCDML.FUNC_getID() > MENU_ID_OF_INSTANCE_2)
+    instance_id = 1;
+
+  UI_handle_OP(param, 5, instance_id);
+}
+
+void UI_handle_OP(uint8_t param, uint8_t op, uint8_t instance_id)
+{
+  bool state = bitRead(configuration.dexed[instance_id].op_enabled, op);
+
+  if (LCDML.FUNC_setup())         // ****** SETUP *********
+  {
+    // setup function
+    lcd.setCursor(0, 0);
+    lcd.print(F("Operator "));
+    lcd.print(op + 1);
+  }
+
+  if (LCDML.FUNC_loop())          // ****** LOOP *********
+  {
+    if (LCDML.BT_checkEnter())
+    {
+      LCDML.FUNC_goBackToMenu();
+    }
+    else if (LCDML.BT_checkUp() && state == true)
+      bitClear(configuration.dexed[instance_id].op_enabled, op);
+    else if (LCDML.BT_checkDown() && state == false)
+      bitSet(configuration.dexed[instance_id].op_enabled, op);
+  }
+
+  lcd.setCursor(0, 1);
+  if (state == true)
+  {
+    lcd.print(F("[ENABLED ]"));
+  }
+  else
+  {
+    lcd.print(F("[DISABLED]"));
+  }
+  MicroDexed[instance_id]->setOPs(configuration.dexed[instance_id].op_enabled);
+  MicroDexed[instance_id]->doRefreshVoice();
+
+  if (LCDML.FUNC_close())     // ****** STABLE END *********
+  {
+    // you can here reset some global vars or do nothing
+    eeprom_write();
+  }
+}
+
 void UI_func_information(uint8_t param)
 {
   if (LCDML.FUNC_setup())         // ****** SETUP *********
diff --git a/config.h b/config.h
index 6c31157..2457409 100644
--- a/config.h
+++ b/config.h
@@ -386,7 +386,9 @@ enum { DEXED, REVERB, DELAY, CHORUS };
 #define AT_ASSIGN_MAX 7
 #define AT_ASSIGN_DEFAULT 0 // Bitmapped: 0: Pitch, 1: Amp, 2: Bias
 
-#define OP_ENABLED_DEFAULT 0x3f
+#define OP_ENABLED_MIN 0
+#define OP_ENABLED_MAX 0x3f
+#define OP_ENABLED_DEFAULT OP_ENABLED_MAX
 
 #define PORTAMENTO_MODE_MIN 0
 #define PORTAMENTO_MODE_MAX 1