diff --git a/src/mame/drivers/mpu4.c b/src/mame/drivers/mpu4.c
index 1d398a5c3af..c7ef278d9fc 100644
--- a/src/mame/drivers/mpu4.c
+++ b/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
 				{
diff --git a/src/mame/drivers/segas16b.c b/src/mame/drivers/segas16b.c
index 9ac587bc398..f633cc2297a 100644
--- a/src/mame/drivers/segas16b.c
+++ b/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();
diff --git a/src/mame/machine/bfm_bd1.c b/src/mame/machine/bfm_bd1.c
index 5328d2e727e..996c26b3578 100644
--- a/src/mame/machine/bfm_bd1.c
+++ b/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
 		{
@@ -235,7 +235,7 @@ void bfm_bd1_t::blank(int data)
 		{
 			for (int i = 0; i < 15; i++)
 			{
-					m_attrs[i] = AT_BLANK;
+				m_attrs[i] = AT_BLANK;
 			}
 		}
 		break;
diff --git a/src/mame/video/model1.c b/src/mame/video/model1.c
index 661f3c02d35..5664178f82f 100644
--- a/src/mame/video/model1.c
+++ b/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));