diff --git a/src/mess/drivers/osi.c b/src/mess/drivers/osi.c
index b1c79536f32..9de6d4cfa6e 100644
--- a/src/mess/drivers/osi.c
+++ b/src/mess/drivers/osi.c
@@ -261,18 +261,27 @@ DISCRETE_SOUND_END
 
 READ8_MEMBER( sb2m600_state::keyboard_r )
 {
-	if (ioport("Reset")->read())
-		machine().device(M6502_TAG)->reset();
-
-	static const char *const keynames[] = { "ROW0", "ROW1", "ROW2", "ROW3", "ROW4", "ROW5", "ROW6", "ROW7" };
+	if (m_io_reset->read())
+		m_maincpu->reset();
 
 	UINT8 data = 0xff;
-	int bit;
 
-	for (bit = 0; bit < 8; bit++)
-	{
-		if (!BIT(m_keylatch, bit)) data &= ioport(keynames[bit])->read();
-	}
+	if (!BIT(m_keylatch, 0))
+		data &= m_io_row0->read();
+	if (!BIT(m_keylatch, 1))
+		data &= m_io_row1->read();
+	if (!BIT(m_keylatch, 2))
+		data &= m_io_row2->read();
+	if (!BIT(m_keylatch, 3))
+		data &= m_io_row3->read();
+	if (!BIT(m_keylatch, 4))
+		data &= m_io_row4->read();
+	if (!BIT(m_keylatch, 5))
+		data &= m_io_row5->read();
+	if (!BIT(m_keylatch, 6))
+		data &= m_io_row6->read();
+	if (!BIT(m_keylatch, 7))
+		data &= m_io_row7->read();
 
 	return data;
 }
@@ -281,7 +290,7 @@ WRITE8_MEMBER( sb2m600_state::keyboard_w )
 {
 	m_keylatch = data;
 
-	if (ioport("Sound")->read())
+	if (m_io_sound->read())
 		discrete_sound_w(m_discrete, space, NODE_01, (data >> 2) & 0x0f);
 }
 
diff --git a/src/mess/includes/osi.h b/src/mess/includes/osi.h
index d37c4c1acfc..295c346ba9d 100644
--- a/src/mess/includes/osi.h
+++ b/src/mess/includes/osi.h
@@ -30,24 +30,27 @@ class sb2m600_state : public driver_device
 public:
 	sb2m600_state(const machine_config &mconfig, device_type type, const char *tag)
 		: driver_device(mconfig, type, tag),
-			m_maincpu(*this, M6502_TAG),
-			m_cassette(*this, CASSETTE_TAG),
-			m_discrete(*this, DISCRETE_TAG),
-			m_ram(*this, RAM_TAG),
-			m_video_ram(*this, "video_ram"),
-			m_color_ram(*this, "color_ram")
+	m_maincpu(*this, M6502_TAG),
+	m_cassette(*this, CASSETTE_TAG),
+	m_discrete(*this, DISCRETE_TAG),
+	m_ram(*this, RAM_TAG),
+	m_video_ram(*this, "video_ram"),
+	m_color_ram(*this, "color_ram"),
+	m_io_row0(*this, "ROW0"),
+	m_io_row1(*this, "ROW1"),
+	m_io_row2(*this, "ROW2"),
+	m_io_row3(*this, "ROW3"),
+	m_io_row4(*this, "ROW4"),
+	m_io_row5(*this, "ROW5"),
+	m_io_row6(*this, "ROW6"),
+	m_io_row7(*this, "ROW7"),
+	m_io_sound(*this, "Sound"),
+	m_io_reset(*this, "Reset")
 	{ }
 
-	required_device<cpu_device> m_maincpu;
-	required_device<cassette_image_device> m_cassette;
-	optional_device<discrete_sound_device> m_discrete;
-	required_device<ram_device> m_ram;
-
 	virtual void machine_start();
-
 	virtual void video_start();
 	UINT32 screen_update(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect);
-
 	DECLARE_READ8_MEMBER( keyboard_r );
 	DECLARE_WRITE8_MEMBER( keyboard_w );
 	DECLARE_WRITE8_MEMBER( ctrl_w );
@@ -60,13 +63,29 @@ public:
 	/* video state */
 	int m_32;
 	int m_coloren;
-	required_shared_ptr<UINT8> m_video_ram;
-	optional_shared_ptr<UINT8> m_color_ram;
+	UINT8 *m_p_chargen;
 
 	/* floppy state */
 	int m_fdc_index;
 	TIMER_CALLBACK_MEMBER(setup_beep);
 	DECLARE_WRITE_LINE_MEMBER(osi470_index_callback);
+
+	required_device<cpu_device> m_maincpu;
+	required_device<cassette_image_device> m_cassette;
+	optional_device<discrete_sound_device> m_discrete;
+	required_device<ram_device> m_ram;
+	required_shared_ptr<UINT8> m_video_ram;
+	optional_shared_ptr<UINT8> m_color_ram;
+	required_ioport m_io_row0;
+	required_ioport m_io_row1;
+	required_ioport m_io_row2;
+	required_ioport m_io_row3;
+	required_ioport m_io_row4;
+	required_ioport m_io_row5;
+	required_ioport m_io_row6;
+	required_ioport m_io_row7;
+	required_ioport m_io_sound;
+	required_ioport m_io_reset;
 };
 
 class c1p_state : public sb2m600_state
diff --git a/src/mess/video/osi.c b/src/mess/video/osi.c
index e363d47b1dc..3029f8e6f40 100644
--- a/src/mess/video/osi.c
+++ b/src/mess/video/osi.c
@@ -23,22 +23,17 @@ static PALETTE_INIT( osi630 )
 
 void sb2m600_state::video_start()
 {
+	m_p_chargen = memregion("chargen")->base();
 	UINT16 addr;
 
 	/* randomize video memory contents */
 	for (addr = 0; addr < OSI600_VIDEORAM_SIZE; addr++)
-	{
 		m_video_ram[addr] = machine().rand() & 0xff;
-	}
 
 	/* randomize color memory contents */
 	if (m_color_ram)
-	{
 		for (addr = 0; addr < OSI630_COLORRAM_SIZE; addr++)
-		{
 			m_color_ram[addr] = machine().rand() & 0x0f;
-		}
-	}
 }
 
 /* Video Update */
@@ -59,11 +54,11 @@ UINT32 sb2m600_state::screen_update(screen_device &screen, bitmap_ind16 &bitmap,
 			{
 				UINT8 videoram_data = m_video_ram[videoram_addr];
 				UINT16 charrom_addr = ((videoram_data << 3) | line) & 0x7ff;
-				UINT8 charrom_data = memregion("chargen")->base()[charrom_addr];
+				UINT8 charrom_data = m_p_chargen[charrom_addr];
 
 				for (bit = 0; bit < 8; bit++)
 				{
-					int color = BIT(charrom_data, 7);
+					bool color = BIT(charrom_data, 7);
 
 					if (m_coloren)
 					{
@@ -92,11 +87,11 @@ UINT32 sb2m600_state::screen_update(screen_device &screen, bitmap_ind16 &bitmap,
 			{
 				UINT8 videoram_data = m_video_ram[videoram_addr];
 				UINT16 charrom_addr = ((videoram_data << 3) | line) & 0x7ff;
-				UINT8 charrom_data = memregion("chargen")->base()[charrom_addr];
+				UINT8 charrom_data = m_p_chargen[charrom_addr];
 
 				for (bit = 0; bit < 8; bit++)
 				{
-					int color = BIT(charrom_data, 7);
+					bool color = BIT(charrom_data, 7);
 
 					if (m_coloren)
 					{
@@ -132,7 +127,7 @@ UINT32 uk101_state::screen_update(screen_device &screen, bitmap_ind16 &bitmap, c
 		{
 			UINT8 videoram_data = m_video_ram[videoram_addr++];
 			UINT16 charrom_addr = ((videoram_data << 3) | line) & 0x7ff;
-			UINT8 charrom_data = memregion("chargen")->base()[charrom_addr];
+			UINT8 charrom_data = m_p_chargen[charrom_addr];
 
 			for (bit = 0; bit < 8; bit++)
 			{