Superdrive: report track zero status.

devices/floppy/superdrive.cpp

@@ -111,6 +111,8 @@ uint8_t MacSuperDrive::status(uint8_t addr)
         return this->has_disk ^ 1;   // reverse logic (active low)!
     case StatusAddr::Write_Protect:
         return this->wr_protect ^ 1; // reverse logic
+    case StatusAddr::Track_Zero:
+        return this->track_zero ^ 1; // reverse logic
     case StatusAddr::Drive_Mode:
         return this->drive_mode;
     case StatusAddr::Drive_Ready:

devices/floppy/superdrive.h

@@ -43,6 +43,7 @@ enum StatusAddr : uint8_t {
     Drive_Exists  = 7,
     Disk_In_Drive = 8,
     Write_Protect = 9,
+    Track_Zero    = 0xA,
     Drive_Mode    = 0xD,
     Drive_Ready   = 0xE,
     Media_Kind    = 0xF