diff --git a/hardware.cpp b/hardware.cpp
index 69cfe9a..43debc6 100644
--- a/hardware.cpp
+++ b/hardware.cpp
@@ -71,7 +71,7 @@ void hardware_init(CPU &cpu) {
 	_cpu = &cpu;
 	memory.begin();
 
-#if defined(DEBUGGING) || defined(CPU_DEBUG)
+#if defined(DEBUGGING) || defined(CPU_DEBUG) || defined(USE_SERIAL)
 	Serial.begin(TERMINAL_SPEED);
 #endif
 
diff --git a/hw_serial_dsp.h b/hw_serial_dsp.h
new file mode 100644
index 0000000..b08a112
--- /dev/null
+++ b/hw_serial_dsp.h
@@ -0,0 +1,14 @@
+#if !defined(__HW_SERIAL_DSP_H__)
+#define __HW_SERIAL_DSP_H__
+
+class hw_serial_dsp: public serial_dsp {
+public:
+	hw_serial_dsp(Print &p): _print(p) {}
+
+	void write(uint8_t b) { _print.write(b); }
+
+private:
+	Print &_print;
+};
+
+#endif
diff --git a/hw_serial_kbd.cpp b/hw_serial_kbd.cpp
index 22d6d88..3ffa5a4 100644
--- a/hw_serial_kbd.cpp
+++ b/hw_serial_kbd.cpp
@@ -1,7 +1,6 @@
 #include <Arduino.h>
 #include "hardware.h"
 
-#if defined(HW_SERIAL_KBD)
 #include "serial_kbd.h"
 #include "hw_serial_kbd.h"
 
@@ -25,4 +24,3 @@ bool hw_serial_kbd::available() {
 void hw_serial_kbd::reset() {
 	_serial.begin(TERMINAL_SPEED);
 }
-#endif
diff --git a/r65emu.h b/r65emu.h
index 6ee76b6..9fbe119 100644
--- a/r65emu.h
+++ b/r65emu.h
@@ -19,5 +19,7 @@
 #include "serial_kbd.h"
 #include "ps2_serial_kbd.h"
 #include "hw_serial_kbd.h"
+#include "serial_dsp.h"
+#include "hw_serial_dsp.h"
 
 #endif
diff --git a/serial_dsp.h b/serial_dsp.h
new file mode 100644
index 0000000..bb459fc
--- /dev/null
+++ b/serial_dsp.h
@@ -0,0 +1,10 @@
+#if !defined(__SERIAL_DSP_H__)
+#define __SERIAL_DSP_H__
+
+class serial_dsp {
+public:
+	virtual void write(uint8_t) =0;
+	virtual void reset() {}
+};
+
+#endif