fix mame-specific unreachable code, JWallace can fix the bfm one

src/mame/drivers/mpu4.c

@@ -972,7 +972,7 @@ WRITE8_MEMBER(mpu4_state::pia_ic5_porta_w)
         of making the game fair, short of simulating the physics of a bouncing ball ;)*/
 		if (data & 0x0f)
 		{
-			switch ((machine().rand()>>5) & 0x2)
+			switch ((machine().rand()>>5) % 0x3)
 			{
 				case 0x00: //Top row
 				{

src/mame/drivers/segas16b.c

@@ -1636,7 +1636,7 @@ static READ16_HANDLER( aceattac_custom_io_r )
 			}
 			break;
 		case 0x3000/2:
-			switch (offset & 3)
+			switch (offset & 7)
 			{
 				case 0:	return state->ioport("HANDX1")->read();
 				case 1:	return state->ioport("TRACKX1")->read();

src/mame/machine/bfm_bd1.c

@@ -191,7 +191,7 @@ void bfm_bd1_t::update_display()
 ///////////////////////////////////////////////////////////////////////////
 void bfm_bd1_t::blank(int data)
 {
-	switch ( data & 0x04 )
+	switch ( data & 0x04 ) // TODO: wrong case values???
 	{
 		case 0x00:	// clear blanking
 		{

src/mame/video/model1.c

@@ -1324,7 +1324,7 @@ static void tgp_render(running_machine &machine, bitmap_rgb32 &bitmap, const rec
 				list += 6;
 				break;
 			case 0xf:
-			case -1:
+			//case -1:
 				goto end;
 			default:
 				LOG_TGP(("VIDEO:   unknown type %d\n", type));