diff --git a/src/emu/machine/z80dart.c b/src/emu/machine/z80dart.c
index e964cb4b5a2..c5998ac21de 100644
--- a/src/emu/machine/z80dart.c
+++ b/src/emu/machine/z80dart.c
@@ -422,6 +422,16 @@ void z80dart_device::take_interrupt(int priority)
 }
 
 
+//-------------------------------------------------
+//  m1_r - interrupt acknowledge
+//-------------------------------------------------
+
+int z80dart_device::m1_r()
+{
+	return z80daisy_irq_ack();
+}
+
+
 
 //**************************************************************************
 //  DART CHANNEL
diff --git a/src/emu/machine/z80dart.h b/src/emu/machine/z80dart.h
index 805c9427f0d..de89be0e6c4 100644
--- a/src/emu/machine/z80dart.h
+++ b/src/emu/machine/z80dart.h
@@ -195,6 +195,9 @@ public:
 	// put data on the input lines
 	void receive_data(int which, UINT8 data) { m_channel[which].receive_data(data); }
 
+	// interrupt acknowledge
+	int m1_r();
+
 	// control line access
 	void cts_w(int which, int state) { m_channel[which].cts_w(state); }
 	void dcd_w(int which, int state) { m_channel[which].dcd_w(state); }