diff -Nru srcold\devices\bus/coco/coco_fdc.cpp src\devices\bus/coco/coco_fdc.cpp
--- srcold\devices\bus/coco/coco_fdc.cpp	2017-08-01 21:20:16.000000000 +0200
+++ src\devices\bus/coco/coco_fdc.cpp	2017-08-02 09:28:58.056055200 +0200
@@ -273,12 +273,8 @@
 	else if (data & 0x40)
 		drive = 3;
 
-	for (int i = 0; i < 4; i++)
-	{
-		floppy_image_device *floppy = m_floppies[i]->get_device();
-		if (floppy)
-			floppy->mon_w(((i == drive) && (data & 0x08)) ? CLEAR_LINE : ASSERT_LINE);
-	}
+	floppy_image_device *floppy = m_floppies[drive]->get_device();
+	floppy->mon_w((data & 0x08) ? CLEAR_LINE : ASSERT_LINE);
 
 	head = ((data & 0x40) && (drive != 3)) ? 1 : 0;