+
+//#define MASTER_CLOCK (12000000)
+//#define SOUND_CLOCK (3579000)
+// MDRV_CPU_ADD("maincpu", M6809, MASTER_CLOCK/3/4)
+// MDRV_CPU_PROGRAM_MAP(defender_map)
+// MDRV_CPU_ADD("soundcpu", M6808, SOUND_CLOCK)
+// MDRV_CPU_PROGRAM_MAP(defender_sound_map)
+
+#define M6808_CLOCK_SPEED_IN_HZ (3579000.0 / 4.0)
+#define M6809_CLOCK_SPEED_IN_HZ (1000000.0)
+
+// Actually, it's 1.1176306230790722 usec
+//#define M6808_CYCLE_IN_USEC (0.9765625)
+#define M6808_CYCLE_IN_USEC (1000000.0 / M6808_CLOCK_SPEEK_IN_HZ)
+#define M6809_CYCLE_IN_USEC (1000000.0 / M6809_CLOCK_SPEED_IN_HZ)