diff --git a/keyboard.h b/keyboard.h
new file mode 100644
index 0000000..f70c0a1
--- /dev/null
+++ b/keyboard.h
@@ -0,0 +1,11 @@
+#ifndef _KEYBOARD_H
+#define _KEYBOARD_H
+
+class Keyboard {
+public:
+	virtual void up(byte) = 0;
+	virtual void down(byte) = 0;
+	virtual void reset() = 0;
+};
+
+#endif
diff --git a/memory.h b/memory.h
index 9944fe8..1b87d91 100644
--- a/memory.h
+++ b/memory.h
@@ -6,6 +6,14 @@
 
 typedef unsigned char byte;
 
+class Stream;
+
+class Checkpointable {
+public:
+	virtual void checkpoint(Stream &s) = 0;
+	virtual void restore(Stream &s) = 0;
+};
+
 class Memory {
 public:
 	typedef unsigned short address;
diff --git a/r65emu.h b/r65emu.h
index 26dd1cc..47b7166 100644
--- a/r65emu.h
+++ b/r65emu.h
@@ -9,6 +9,7 @@
 #include "prom.h"
 #include "ps2drv.h"
 #include "utftdisplay.h"
+#include "keyboard.h"
 #include "hardware.h"
 
 #endif
diff --git a/ram.h b/ram.h
index 5ebd418..2c18d18 100644
--- a/ram.h
+++ b/ram.h
@@ -1,17 +1,17 @@
 #ifndef _RAM_H
 #define _RAM_H
 
-class ram: public Memory::Device {
+class ram: public Memory::Device, public Checkpointable {
 public:
-  virtual void operator= (byte c) { _mem[_acc] = c; }
-  virtual operator byte () { return _mem[_acc]; }
+	virtual void operator= (byte c) { _mem[_acc] = c; }
+	virtual operator byte () { return _mem[_acc]; }
 
-  void checkpoint(Stream &s) { s.write(_mem, sizeof(_mem)); }
-  void restore(Stream &s) { s.readBytes((char *)_mem, sizeof(_mem)); }
+	virtual void checkpoint(Stream &s) { s.write(_mem, sizeof(_mem)); }
+	virtual void restore(Stream &s) { s.readBytes((char *)_mem, sizeof(_mem)); }
 
-  ram (): Memory::Device(sizeof(_mem)) {}
+	ram (): Memory::Device(sizeof(_mem)) {}
 
 private:
-  byte _mem[1024];
+	byte _mem[1024];
 };
 #endif
diff --git a/spiram.h b/spiram.h
index a98683d..82783ab 100644
--- a/spiram.h
+++ b/spiram.h
@@ -1,16 +1,16 @@
 #ifndef __SPIRAM_H__
 #define __SPIRAM_H__
 
-class spiram: public Memory::Device {
+class spiram: public Memory::Device, public Checkpointable {
 public:
-  virtual void operator= (byte c);
-  virtual operator byte ();
+	virtual void operator= (byte c);
+	virtual operator byte ();
 
-  void checkpoint(Stream &s);
-  void restore(Stream &s);
+	virtual void checkpoint(Stream &s);
+	virtual void restore(Stream &s);
 
-  spiram(int bytes): Memory::Device(bytes) {}
-  void begin(byte cs, int module);
+	spiram(int bytes): Memory::Device(bytes) {}
+	void begin(byte cs, int module);
 };
 
 #endif
diff --git a/utftdisplay.h b/utftdisplay.h
index cfb81ee..9b164a3 100644
--- a/utftdisplay.h
+++ b/utftdisplay.h
@@ -3,13 +3,16 @@
 
 class Stream;
 
-class UTFTDisplay: public Memory::Device {
+class UTFTDisplay: public Memory::Device, public Checkpointable {
 public:
 	void begin(unsigned bg, unsigned fg);
 	void clear();
 	void error(char *);
 	void status(const char *);
 
+	virtual void checkpoint(Stream &s) = 0;
+	virtual void restore(Stream &s) = 0;
+
 protected:
 	UTFTDisplay(unsigned size): Memory::Device(size) {}