diff --git a/src/core/cpu_inline.h b/src/core/cpu_inline.h
index a0e04335d..42be81739 100644
--- a/src/core/cpu_inline.h
+++ b/src/core/cpu_inline.h
@@ -729,9 +729,6 @@ static BYTE INLINE fds_rd_mem(WORD address, BYTE made_tick) {
 			} else if (!fds.drive.scan) {
 				cpu.openbus |= 0x02;
 			}
-#if !defined (RELEASE)
-			//fprintf(stderr, "0x%04X 0x%02X\n", address, cpu.openbus);
-#endif
 			return (TRUE);
 		}
 		if (address == 0x4033) {
@@ -2016,7 +2013,6 @@ static BYTE INLINE fds_wr_mem(WORD address, BYTE value) {
 			if (!fds.drive.enabled_dsk_reg) {
 				return (TRUE);
 			}
-
 			fds.drive.data_external_connector = value;
 			return (TRUE);
 		}
@@ -2028,51 +2024,43 @@ static BYTE INLINE fds_wr_mem(WORD address, BYTE value) {
 		if (fds.drive.enabled_snd_reg) {
 			if ((address >= 0x4040) && (address <= 0x407F)) {
 				fds.snd.wave.data[address & 0x003F] = value & 0x3F;
-
 				return (TRUE);
 			}
 			if (address == 0x4080) {
 				fds.snd.volume.speed = value & 0x3F;
 				fds.snd.volume.increase = value & 0x40;
 				fds.snd.volume.mode = value & 0x80;
-
 				return (TRUE);
 			}
 			if (address == 0x4082) {
 				fds.snd.main.frequency = (fds.snd.main.frequency & 0xFF00) | value;
-
 				return (TRUE);
 			}
 			if (address == 0x4083) {
 				fds.snd.main.frequency = ((value & 0x0F) << 8) | (fds.snd.main.frequency & 0x00FF);
 				fds.snd.envelope.disabled = value & 0x40;
 				fds.snd.main.silence = value & 0x80;
-
 				return (TRUE);
 			}
 			if (address == 0x4084) {
 				fds.snd.sweep.speed = value & 0x3F;
 				fds.snd.sweep.increase = value & 0x40;
 				fds.snd.sweep.mode = value & 0x80;
-
 				return (TRUE);
 			}
 			if (address == 0x4085) {
 				fds.snd.sweep.bias = ((SBYTE) (value << 1)) / 2;
 				fds.snd.modulation.index = 0;
-
 				return (TRUE);
 			}
 			if (address == 0x4086) {
 				fds.snd.modulation.frequency = (fds.snd.modulation.frequency & 0xFF00) | value;
-
 				return (TRUE);
 			}
 			if (address == 0x4087) {
 				fds.snd.modulation.frequency = ((value & 0x0F) << 8)
 			        		| (fds.snd.modulation.frequency & 0x00FF);
 				fds.snd.modulation.disabled = value & 0x80;
-
 				return (TRUE);
 			}
 			if (address == 0x4088) {
@@ -2090,18 +2078,15 @@ static BYTE INLINE fds_wr_mem(WORD address, BYTE value) {
 					}
 					fds.snd.modulation.data[a + 1] = fds.snd.modulation.data[a];
 				}
-
 				return (TRUE);
 			}
 			if (address == 0x4089) {
 				fds.snd.wave.writable = value & 0x80;
 				fds.snd.wave.volume = value & 0x03;
-
 				return (TRUE);
 			}
 			if (address == 0x408A) {
 				fds.snd.envelope.speed = value;
-
 				return (TRUE);
 			}
 		}
diff --git a/src/core/fds.c b/src/core/fds.c
index 36e6a78ba..566326321 100644
--- a/src/core/fds.c
+++ b/src/core/fds.c
@@ -42,6 +42,8 @@ typedef struct _fds_diff_ele {
 void fds_init(void) {
 	memset(&fds, 0x00, sizeof(fds));
 
+	fds.side.change.new_side = 0xFF;
+
 	fds.drive.disk_ejected = TRUE;
 	fds.drive.motor_on = TRUE;
 	fds.drive.enabled_dsk_reg = 0x01;
@@ -249,9 +251,7 @@ void fds_disk_op(WORD type, BYTE side_to_insert) {
 #endif
 
 			fds.side.data = (WORD *) malloc(fds.info.sides_size[side_to_insert] * sizeof(WORD));
-
 			fds.side.counted_files = 0xFFFF;
-
 			break;
 	}
 
@@ -405,10 +405,12 @@ void fds_disk_op(WORD type, BYTE side_to_insert) {
 			break;
 		case FDS_DISK_SELECT_AND_INSERT:
 			type = FDS_DISK_INSERT;
+			fds.side.change.new_side = 0xFF;
 			fds.drive.side_inserted = side_to_insert;
 			fds_diff_op(FDS_OP_READ, 0, 0);
 			goto fds_disk_op_start;
 		case FDS_DISK_SELECT:
+			fds.side.change.new_side = 0xFF;
 			fds.drive.side_inserted = side_to_insert;
 			text_add_line_info(1, "Disk [cyan]%d [normal]side [cyan]%c [brown]selected",
 					(fds.drive.side_inserted / 2) + 1, (fds.drive.side_inserted & 0x01) + 'A');
diff --git a/src/core/fds.h b/src/core/fds.h
index 1d2c0e390..573fbc65d 100644
--- a/src/core/fds.h
+++ b/src/core/fds.h
@@ -86,6 +86,10 @@ EXTERNC struct _fds {
 				uint32_t position;
 			} block_4;
 		} file[0xFF];
+		struct _fds_side_change {
+			BYTE new_side;
+			uint32_t delay;
+		} change;
 		WORD *data;
 		uint32_t counted_files;
 	} side;
diff --git a/src/core/mappers/mapper_FDS.c b/src/core/mappers/mapper_FDS.c
index 603fbf7ff..654ac1cc8 100644
--- a/src/core/mappers/mapper_FDS.c
+++ b/src/core/mappers/mapper_FDS.c
@@ -71,6 +71,14 @@ void extcl_cpu_every_cycle_FDS(void) {
 		}
 	}
 
+	/* se c'e' un delay aspetto */
+	if (fds.side.change.delay > 0) {
+		if (!(--fds.side.change.delay)) {
+			fds_disk_op(FDS_DISK_SELECT_AND_INSERT, fds.side.change.new_side);
+		}
+		return;
+	}
+
 	/* no disco, no party */
 	if (fds.drive.disk_ejected) {
 		fds.drive.delay = 1000;
diff --git a/src/gui/mainWindow.cpp b/src/gui/mainWindow.cpp
index 65029992b..c061afb63 100644
--- a/src/gui/mainWindow.cpp
+++ b/src/gui/mainWindow.cpp
@@ -1211,7 +1211,12 @@ void mainWindow::ctrl_disk_side(QAction *action) {
 	} else {
 		action->setEnabled(false);
 	}
-	if (side == fds.drive.side_inserted) {
+
+	if (fds.side.change.new_side == 0xFF) {
+		if (side == fds.drive.side_inserted) {
+			action->setChecked(true);
+		}
+	} else if (side == fds.side.change.new_side) {
 		action->setChecked(true);
 	}
 }
@@ -1821,9 +1826,9 @@ void mainWindow::s_disk_side() {
 	int side = QVariant(((QObject *)sender())->property("myValue")).toInt();
 
 	if (side == 0xFFF) {
-		side = fds.drive.side_inserted;
-		if (++side >= fds.info.total_sides) {
-			side = 0;
+		side = fds.drive.side_inserted ^ 0x01;
+		if (side >= fds.info.total_sides) {
+			return;
 		}
 	}
 
@@ -1831,7 +1836,15 @@ void mainWindow::s_disk_side() {
 		return;
 	}
 
-	fds_disk_op(FDS_DISK_SELECT, side);
+	if (fds.drive.disk_ejected) {
+		fds.side.change.new_side = 0xFF;
+		fds.side.change.delay = 0;
+		fds_disk_op(FDS_DISK_SELECT, side);
+	} else {
+		fds.side.change.new_side = side;
+		fds.side.change.delay = 3000000;
+		fds_disk_op(FDS_DISK_EJECT, 0);
+	}
 
 	update_menu_nes();
 }