diff --git a/src/devices/video/ef9340_1.cpp b/src/devices/video/ef9340_1.cpp
index 12439dd12e7..01cb926f1f3 100644
--- a/src/devices/video/ef9340_1.cpp
+++ b/src/devices/video/ef9340_1.cpp
@@ -2,8 +2,16 @@
 // copyright-holders:Wilbert Pol
 /***************************************************************************
 
-    Thomson EF9340 + EF9341 teletext graphics chips with 1KB external
-    character ram.
+Thomson EF9340 + EF9341 teletext graphics chips with 1KB external character ram.
+
+TODO:
+- busy state (right now it is immediate)
+- read slice
+- character blinking mode
+- character underline mode
+- character width/height doubling
+- window boxing/conceal
+- Y zoom
 
 ***************************************************************************/
 
@@ -52,7 +60,7 @@ void ef9340_1_device::device_start()
 	// zerofill
 	m_ef9341.TA = 0;
 	m_ef9341.TB = 0;
-	m_ef9341.busy = 0;
+	m_ef9341.busy = false;
 
 	m_ef9340.X = 0;
 	m_ef9340.Y = 0;
@@ -102,7 +110,7 @@ uint16_t ef9340_1_device::ef9340_get_c_addr(uint8_t x, uint8_t y)
 	{
 		return 0x300 | ( ( y & 0x07 ) << 5 ) | ( y & 0x18 ) | ( x & 0x07 );
 	}
-	return y << 5 | x;
+	return ( y & 0x1f ) << 5 | ( x & 0x1f );
 }
 
 
@@ -144,7 +152,7 @@ void ef9340_1_device::ef9341_write( uint8_t command, uint8_t b, uint8_t data )
 		if ( b )
 		{
 			m_ef9341.TB = data;
-			m_ef9341.busy = 0x80;
+			m_ef9341.busy = true;
 			switch( m_ef9341.TB & 0xE0 )
 			{
 			case 0x00:  /* Begin row */
@@ -169,8 +177,10 @@ void ef9340_1_device::ef9341_write( uint8_t command, uint8_t b, uint8_t data )
 			case 0xC0:  /* Load Y0 */
 				m_ef9340.Y0 = m_ef9341.TA & 0x3F;
 				break;
+			case 0xE0:  /* Not interpreted */
+				break;
 			}
-			m_ef9341.busy = 0;
+			m_ef9341.busy = false;
 		}
 		else
 		{
@@ -184,7 +194,7 @@ void ef9340_1_device::ef9341_write( uint8_t command, uint8_t b, uint8_t data )
 			uint16_t addr = ef9340_get_c_addr( m_ef9340.X, m_ef9340.Y ) & 0x3ff;
 
 			m_ef9341.TB = data;
-			m_ef9341.busy = 0x80;
+			m_ef9341.busy = true;
 			switch ( m_ef9340.M & 0xE0 )
 			{
 				case 0x00:  /* Write */
@@ -231,7 +241,7 @@ void ef9340_1_device::ef9341_write( uint8_t command, uint8_t b, uint8_t data )
 				default:    /* Illegal */
 					break;
 			}
-			m_ef9341.busy = 0;
+			m_ef9341.busy = false;
 		}
 		else
 		{
@@ -255,7 +265,7 @@ uint8_t ef9340_1_device::ef9341_read( uint8_t command, uint8_t b )
 		}
 		else
 		{
-			data = m_ef9341.busy;
+			data = (m_ef9341.busy) ? 0x80 : 0;
 		}
 	}
 	else
@@ -283,11 +293,12 @@ void ef9340_1_device::ef9340_scanline(int vpos)
 	for ( int i = 0; i < 40 * 8; i++ )
 		m_tmp_bitmap.pix16(vpos, i) = 0;
 
+	// display automaton active at 40-290, or 32-242
 	int max_vpos = ( m_ef9340.R & 0x40 ) ? 250 : 210;
 
 	if ( m_ef9340.R & 0x01 && vpos < max_vpos )
 	{
-		int y = vpos - 0;
+		int y = vpos;
 		int y_row, slice;
 		uint8_t fg = 0;
 		uint8_t bg = 0;
@@ -310,7 +321,7 @@ void ef9340_1_device::ef9340_scanline(int vpos)
 		else
 		{
 			// Displaying regular row
-			y_row = (y - 10) / 10;
+			y_row = ((m_ef9340.Y0 & 0x1f) + (y - 10) / 10) % 24;
 			slice = (y - 10) % 10;
 		}
 
diff --git a/src/devices/video/ef9340_1.h b/src/devices/video/ef9340_1.h
index 56ce0459b1c..f2d9d906731 100644
--- a/src/devices/video/ef9340_1.h
+++ b/src/devices/video/ef9340_1.h
@@ -59,7 +59,7 @@ protected:
 	{
 		uint8_t   TA;
 		uint8_t   TB;
-		uint8_t   busy;
+		bool      busy;
 	} m_ef9341;
 
 	struct
@@ -71,9 +71,9 @@ protected:
 		uint8_t   M;
 	} m_ef9340;
 
-	uint8_t   m_ef934x_ram_a[1024];
-	uint8_t   m_ef934x_ram_b[1024];
-	uint8_t   m_ef934x_ext_char_ram[2048];   /* The G7400 has 2KB of external ram hooked up. The datasheet only describes how to hookup 1KB. */
+	uint8_t   m_ef934x_ram_a[0x400]; // A10 to GND
+	uint8_t   m_ef934x_ram_b[0x400]; // A10 to GND
+	uint8_t   m_ef934x_ext_char_ram[0x800]; // The G7400 has 2KB of external ram hooked up. The datasheet only describes how to hookup 1KB.
 };
 
 
diff --git a/src/mame/drivers/odyssey2.cpp b/src/mame/drivers/odyssey2.cpp
index f85628647f5..f638f336871 100644
--- a/src/mame/drivers/odyssey2.cpp
+++ b/src/mame/drivers/odyssey2.cpp
@@ -22,7 +22,7 @@ Odyssey 2/Videopac hardware notes:
 Videopac+ G7400 hardware notes:
 - same base hardware
 - Intel 8243 I/O expander
-- EF9340 + EF9341 graphics chips
+- EF9340 + EF9341 graphics chips + 6KB VRAM(3*2128, only 4KB used)
 - larger keyboard
 
 XTAL notes (differs per model):
@@ -46,7 +46,10 @@ TODO:
 - ppp(the tetris game) does not work properly on PAL, is this homebrew NTSC-only,
   or is it due to PAL video timing? The game does mid-scanline updates
 - add 824x vs ef934x collision detection, none of the games use it
-- g7400 rally doesn't work, car keeps exploding
+- g7400 rally doesn't work, car keeps exploding, it is related to ef9341_read:
+  If you invert the returned RAM value, the USA map looks better. If you always
+  return 0, the game can be played but the car is invincible
+- g7400 flashp doesn't work, also related to ef9341_read?
 - g7400 probably has different video timing too (not same as g7000)
 - g7400 graphics problems, mostly due to missing features in ef934x