diff --git a/artiq/devices/rtio_core.py b/artiq/devices/rtio_core.py
new file mode 100644
index 000000000..2c0b1988f
--- /dev/null
+++ b/artiq/devices/rtio_core.py
@@ -0,0 +1,39 @@
+from artiq.language.core import *
+
+
+class RTIOOut(AutoContext):
+    parameters = "channel"
+
+    def build(self):
+        self.previous_timestamp = int64(0)
+        self.previous_value = 0
+
+    kernel_attr = "previous_timestamp previous_value"
+
+    @kernel
+    def _set_value(self, value):
+        if self.previous_value != value:
+            if self.previous_timestamp == now():
+                syscall("rtio_replace", now(), self.channel, value)
+            else:
+                syscall("rtio_set", now(), self.channel, value)
+            self.previous_timestamp = now()
+            self.previous_value = value
+
+    @kernel
+    def sync(self):
+        syscall("rtio_sync", self.channel)
+
+    @kernel
+    def on(self):
+        self._set_value(1)
+
+    @kernel
+    def off(self):
+        self._set_value(0)
+
+    @kernel
+    def pulse(self, duration):
+        self.on()
+        delay(duration)
+        self.off()
diff --git a/artiq/devices/ttl_core.py b/artiq/devices/ttl_core.py
deleted file mode 100644
index 4320e6a9c..000000000
--- a/artiq/devices/ttl_core.py
+++ /dev/null
@@ -1,11 +0,0 @@
-from artiq.language.core import *
-
-
-class TTLOut(AutoContext):
-    parameters = "channel"
-
-    @kernel
-    def pulse(self, duration):
-        syscall("rtio_set", now(), self.channel, 1)
-        delay(duration)
-        syscall("rtio_set", now(), self.channel, 0)