diff --git a/src/devices/cpu/tms0980/tms0980.c b/src/devices/cpu/tms0980/tms0980.c
index 0bd70d45bab..e487564ef23 100644
--- a/src/devices/cpu/tms0980/tms0980.c
+++ b/src/devices/cpu/tms0980/tms0980.c
@@ -1300,6 +1300,15 @@ void tms1xxx_cpu_device::op_sbl()
 }
 
 
+// TMS1980-specific
+
+void tms1980_cpu_device::op_tdo()
+{
+	// TDO: transfer accumulator and status(not status_latch!) to O-output
+	write_o_output(m_status << 4 | m_a);
+}
+
+
 // TMS0270-specific
 
 void tms0270_cpu_device::op_setr()
diff --git a/src/devices/cpu/tms0980/tms0980.h b/src/devices/cpu/tms0980/tms0980.h
index 47600ba6ed0..7101a614e2f 100644
--- a/src/devices/cpu/tms0980/tms0980.h
+++ b/src/devices/cpu/tms0980/tms0980.h
@@ -418,8 +418,7 @@ protected:
 	virtual UINT8 read_k_input() { return tms1xxx_cpu_device::read_k_input(); }
 
 	virtual void op_setr() { tms1xxx_cpu_device::op_setr(); }
-	virtual void op_rstr() { tms1xxx_cpu_device::op_rstr(); }
-	virtual void op_tdo() { tms1xxx_cpu_device::op_tdo(); }
+	virtual void op_tdo();
 };