diff --git a/software/filemanager/dos.cc b/software/filemanager/dos.cc
index fab27055..c58f5073 100644
--- a/software/filemanager/dos.cc
+++ b/software/filemanager/dos.cc
@@ -132,6 +132,14 @@ void Dos :: parse_command(Message *command, Message **reply, Message **status)
        if (cmd >= 0x16 && cmd <= 0x1f)   command->message[1] = 0xff;
        if (cmd >= 0x23 && cmd <= 0x2f)   command->message[1] = 0xff;
     }
+    if (ultimatedosversion == -2)
+    {
+       int cmd = command->message[1];
+       if (cmd >= 0x09 && cmd <= 0x0f)   command->message[1] = 0xff;
+       if (cmd >= 0x16 && cmd <= 0x1f)   command->message[1] = 0xff;
+       if (cmd >= 0x23 && cmd <= 0x2f)   command->message[1] = 0xff;
+       if (cmd == 0x15)   command->message[1] = 0x17;
+    }
     
     switch(command->message[1]) {
         case DOS_CMD_IDENTIFY:
diff --git a/software/io/c64/c64.cc b/software/io/c64/c64.cc
index 8777316a..7a18cd36 100644
--- a/software/io/c64/c64.cc
+++ b/software/io/c64/c64.cc
@@ -216,7 +216,8 @@ void C64 :: set_emulation_flags(cart_def *def)
         if(getFpgaCapabilities() & CAPAB_COMMAND_INTF) {
         	int choice = cfg->get_value(CFG_CMD_ENABLE);
         	CMD_IF_SLOT_ENABLE = !!choice;
-		ultimatedosversion = choice;
+		if (choice != 2 || ultimatedosversion != -2)
+		   ultimatedosversion = choice;
             CMD_IF_SLOT_BASE = 0x47; // $DF1C
         }
     }
diff --git a/software/userinterface/config_menu.cc b/software/userinterface/config_menu.cc
index 4a27ddd9..dcad651b 100644
--- a/software/userinterface/config_menu.cc
+++ b/software/userinterface/config_menu.cc
@@ -8,6 +8,10 @@ extern "C" {
 #include "config.h"
 #include "config_menu.h"
 
+
+extern int ultimatedosversion;
+
+
 /************************/
 /* ConfigBrowser Object */
 /************************/
@@ -147,6 +151,10 @@ int ConfigBrowser :: handle_key(int c)
         	}
         	ret = -2;
             break;
+        case KEY_CTRL_HOME:
+	    if (ultimatedosversion == 2)
+	       ultimatedosversion = -2;
+	    break;
         case KEY_DOWN: // down
             state->down(1);
             break;