diff --git a/src/mess/includes/nes.h b/src/mess/includes/nes.h
index f3bca66e2af..9ac9c4db8c7 100644
--- a/src/mess/includes/nes.h
+++ b/src/mess/includes/nes.h
@@ -452,8 +452,11 @@ public:
 
 	nes_state(const machine_config &mconfig, device_type type, const char *tag)
 		: driver_device(mconfig, type, tag),
-		m_cartslot(*this, "nes_slot")
-	{ }
+			m_maincpu(*this, "maincpu"),
+			m_ppu(*this, "ppu"),
+			m_sound(*this, "nessound"),
+			m_cartslot(*this, "nes_slot")
+		{ }
 
 	/* input_related - this part has to be cleaned up (e.g. in_2 and in_3 are not really necessary here...) */
 	nes_input m_in_0, m_in_1, m_in_2, m_in_3;
@@ -482,7 +485,10 @@ public:
 	UINT8      *m_vram;
 	UINT8      *m_ciram; //PPU nametable RAM - external to PPU!
 
-	optional_device<nes_cart_slot_device> m_cartslot;   //mandatory
+	required_device<cpu_device> m_maincpu;
+	required_device<ppu2c0x_device> m_ppu;
+	required_device<device_t> m_sound;
+	optional_device<nes_cart_slot_device> m_cartslot;
 
 	int nes_ppu_vidaccess(int address, int data);
 	void ppu_nmi(int *ppu_regs);
@@ -545,10 +551,6 @@ protected:
 	virtual void device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr);
 
 private:
-	/* devices */
-	cpu_device        *m_maincpu;
-	ppu2c0x_device    *m_ppu;
-	device_t          *m_sound;
 	memory_bank       *m_prg_bank_mem[5];
 };
 
diff --git a/src/mess/machine/nes.c b/src/mess/machine/nes.c
index 724aed71af0..5699b319f17 100644
--- a/src/mess/machine/nes.c
+++ b/src/mess/machine/nes.c
@@ -80,36 +80,29 @@ static void nes_state_register( running_machine &machine )
 
 void nes_state::machine_start()
 {
-	m_maincpu           = machine().device<cpu_device>("maincpu");
-	m_ppu               = machine().device<ppu2c0x_device>("ppu");
-	m_sound             = machine().device("nessound");
+	for (int i = 0; i < 9; i++)
+	{
+		char str[7];
+		sprintf(str, "FCKEY%i", i);
+		m_io_fckey[i] = ioport(str);
+	}
+	for (int i = 0; i < 13; i++)
+	{
+		char str[9];
+		sprintf(str, "SUBKEY%i", i);
+		m_io_subkey[i] = ioport(str);
+	}
+	for (int i = 0; i < 4; i++)
+	{
+		char str[5];
+		sprintf(str, "PAD%i", i + 1);
+		m_io_pad[i] = ioport(str);
+		sprintf(str, "MAH%i", i);
+		m_io_mahjong[i] = ioport(str);
+	}
+
 	m_io_ctrlsel        = ioport("CTRLSEL");
-	m_io_fckey[0]       = ioport("FCKEY0");
-	m_io_fckey[1]       = ioport("FCKEY1");
-	m_io_fckey[2]       = ioport("FCKEY2");
-	m_io_fckey[3]       = ioport("FCKEY3");
-	m_io_fckey[4]       = ioport("FCKEY4");
-	m_io_fckey[5]       = ioport("FCKEY5");
-	m_io_fckey[6]       = ioport("FCKEY6");
-	m_io_fckey[7]       = ioport("FCKEY7");
-	m_io_fckey[8]       = ioport("FCKEY8");
-	m_io_subkey[0 ]     = ioport("SUBKEY0");
-	m_io_subkey[1 ]     = ioport("SUBKEY1");
-	m_io_subkey[2 ]     = ioport("SUBKEY2");
-	m_io_subkey[3 ]     = ioport("SUBKEY3");
-	m_io_subkey[4 ]     = ioport("SUBKEY4");
-	m_io_subkey[5 ]     = ioport("SUBKEY5");
-	m_io_subkey[6 ]     = ioport("SUBKEY6");
-	m_io_subkey[7 ]     = ioport("SUBKEY7");
-	m_io_subkey[8 ]     = ioport("SUBKEY8");
-	m_io_subkey[9 ]     = ioport("SUBKEY9");
-	m_io_subkey[10]     = ioport("SUBKEY10");
-	m_io_subkey[11]     = ioport("SUBKEY11");
-	m_io_subkey[12]     = ioport("SUBKEY12");
-	m_io_pad[0]         = ioport("PAD1");
-	m_io_pad[1]         = ioport("PAD2");
-	m_io_pad[2]         = ioport("PAD3");
-	m_io_pad[3]         = ioport("PAD4");
+	m_io_paddle         = ioport("PADDLE");
 	m_io_cc_left        = ioport("CC_LEFT");
 	m_io_cc_right       = ioport("CC_RIGHT");
 	m_io_zapper1_t      = ioport("ZAPPER1_T");
@@ -118,11 +111,6 @@ void nes_state::machine_start()
 	m_io_zapper2_t      = ioport("ZAPPER2_T");
 	m_io_zapper2_x      = ioport("ZAPPER2_X");
 	m_io_zapper2_y      = ioport("ZAPPER2_Y");
-	m_io_paddle         = ioport("PADDLE");
-	m_io_mahjong[0]     = ioport("MAH0");
-	m_io_mahjong[1]     = ioport("MAH1");
-	m_io_mahjong[2]     = ioport("MAH2");
-	m_io_mahjong[3]     = ioport("MAH3");
 
 	address_space &space = m_maincpu->space(AS_PROGRAM);