Another case of missed inheritance.

src/mame/includes/blstroid.h

@@ -11,7 +11,7 @@ class blstroid_state : public atarigen_state
 public:
 	enum
 	{
-		TIMER_IRQ_OFF,
+		TIMER_IRQ_OFF = TID_UNHALT_CPU+1,
 		TIMER_IRQ_ON
 	};
 

src/mame/video/blstroid.c

@@ -103,7 +103,8 @@ void blstroid_state::device_timer(emu_timer &timer, device_timer_id id, int para
 		update_interrupts();
 		break;
 	default:
-		assert_always(FALSE, "Unknown id in blstroid_state::device_timer");
+		atarigen_state::device_timer(timer, id, param, ptr);
+		break;
 	}
 }