diff --git a/Machines/Apple/AppleIIgs/AppleIIgs.cpp b/Machines/Apple/AppleIIgs/AppleIIgs.cpp
index f672afb76..c740d4f38 100644
--- a/Machines/Apple/AppleIIgs/AppleIIgs.cpp
+++ b/Machines/Apple/AppleIIgs/AppleIIgs.cpp
@@ -470,11 +470,18 @@ class ConcreteMachine:
 							iwm_->set_select(*value & 0x80);
 
 							// Presumably bit 6 selects between two 5.25" drives rather than the two 3.5"?
+							if(*value & 0x40) {
+								iwm_->set_drive(0, &drives_[0]);
+								iwm_->set_drive(1, &drives_[1]);
+							} else {
+								// TODO: add 5.25" drives.
+								// (and any Smartport devices?)
+								iwm_->set_drive(0, nullptr);
+								iwm_->set_drive(1, nullptr);
+							}
 						} else {
 							*value = disk_select_;
 						}
-
-						printf("TODO: Disk interface register [%d; %02x]\n", is_read, *value);
 					break;
 
 					default:
diff --git a/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal.xcscheme b/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal.xcscheme
index b974f72bf..01069c685 100644
--- a/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal.xcscheme	
+++ b/OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal.xcscheme	
@@ -62,7 +62,7 @@
       </Testables>
    </TestAction>
    <LaunchAction
-      buildConfiguration = "Release"
+      buildConfiguration = "Debug"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
       enableASanStackUseAfterReturn = "YES"