diff --git a/src/mame/drivers/ojankohs.cpp b/src/mame/drivers/ojankohs.cpp
index 41cc40f0154..d9058cedc6c 100644
--- a/src/mame/drivers/ojankohs.cpp
+++ b/src/mame/drivers/ojankohs.cpp
@@ -147,17 +147,16 @@ ADDRESS_MAP_START(ojankohs_state::ojankoy_io_map)
 ADDRESS_MAP_END
 
 ADDRESS_MAP_START(ojankohs_state::ccasino_io_map)
-	ADDRESS_MAP_GLOBAL_MASK(0xff)
-	AM_RANGE(0x00, 0x00) AM_READ_PORT("system") AM_WRITE(port_select_w)
-	AM_RANGE(0x01, 0x01) AM_READWRITE(keymatrix_p1_r, ojankohs_rombank_w)
-	AM_RANGE(0x02, 0x02) AM_READWRITE(keymatrix_p2_r, ccasino_coinctr_w)
-	AM_RANGE(0x03, 0x03) AM_READ(ccasino_dipsw3_r) AM_WRITE(ojankohs_adpcm_reset_w)
-	AM_RANGE(0x04, 0x04) AM_READ(ccasino_dipsw4_r) AM_WRITE(ojankohs_flipscreen_w)
-	AM_RANGE(0x05, 0x05) AM_WRITE(ojankohs_msm5205_w)
-	AM_RANGE(0x06, 0x06) AM_DEVREAD("aysnd", ay8910_device, data_r)
-	AM_RANGE(0x06, 0x07) AM_DEVWRITE("aysnd", ay8910_device, data_address_w)
-	AM_RANGE(0x08, 0x0f) AM_WRITE(ccasino_palette_w) AM_SHARE("paletteram")     // 16bit address access
-	AM_RANGE(0x10, 0x11) AM_DEVWRITE("gga", vsystem_gga_device, write)
+	AM_RANGE(0x00, 0x00) AM_MIRROR(0xff00) AM_READ_PORT("system") AM_WRITE(port_select_w)
+	AM_RANGE(0x01, 0x01) AM_MIRROR(0xff00) AM_READWRITE(keymatrix_p1_r, ojankohs_rombank_w)
+	AM_RANGE(0x02, 0x02) AM_MIRROR(0xff00) AM_READWRITE(keymatrix_p2_r, ccasino_coinctr_w)
+	AM_RANGE(0x03, 0x03) AM_MIRROR(0xff00) AM_READ(ccasino_dipsw3_r) AM_WRITE(ojankohs_adpcm_reset_w)
+	AM_RANGE(0x04, 0x04) AM_MIRROR(0xff00) AM_READ(ccasino_dipsw4_r) AM_WRITE(ojankohs_flipscreen_w)
+	AM_RANGE(0x05, 0x05) AM_MIRROR(0xff00) AM_WRITE(ojankohs_msm5205_w)
+	AM_RANGE(0x06, 0x06) AM_MIRROR(0xff00) AM_DEVREAD("aysnd", ay8910_device, data_r)
+	AM_RANGE(0x06, 0x07) AM_MIRROR(0xff00) AM_DEVWRITE("aysnd", ay8910_device, data_address_w)
+	AM_RANGE(0x08, 0x0f) AM_SELECT(0xff00) AM_WRITE(ccasino_palette_w)     // 16bit address access
+	AM_RANGE(0x10, 0x11) AM_MIRROR(0xff00) AM_DEVWRITE("gga", vsystem_gga_device, write)
 ADDRESS_MAP_END
 
 ADDRESS_MAP_START(ojankohs_state::ojankoc_io_map)
@@ -812,7 +811,7 @@ MACHINE_CONFIG_START(ojankohs_state::ccasino)
 
 	MCFG_DEVICE_ADD("gga", VSYSTEM_GGA, XTAL(13'333'000)/2) // divider not verified
 
-	MCFG_VIDEO_START_OVERRIDE(ojankohs_state,ojankoy)
+	MCFG_VIDEO_START_OVERRIDE(ojankohs_state,ccasino)
 
 	/* sound hardware */
 	MCFG_SPEAKER_STANDARD_MONO("mono")
diff --git a/src/mame/includes/ojankohs.h b/src/mame/includes/ojankohs.h
index d4c904ac00c..11df115fcd4 100644
--- a/src/mame/includes/ojankohs.h
+++ b/src/mame/includes/ojankohs.h
@@ -99,6 +99,7 @@ public:
 	DECLARE_MACHINE_START(ojankoy);
 	DECLARE_VIDEO_START(ojankoy);
 	DECLARE_PALETTE_INIT(ojankoy);
+	DECLARE_VIDEO_START(ccasino);
 	DECLARE_MACHINE_START(ojankoc);
 	DECLARE_VIDEO_START(ojankoc);
 	DECLARE_MACHINE_START(common);
diff --git a/src/mame/video/ojankohs.cpp b/src/mame/video/ojankohs.cpp
index f25bd5b3b89..8e3fa06c6c8 100644
--- a/src/mame/video/ojankohs.cpp
+++ b/src/mame/video/ojankohs.cpp
@@ -70,8 +70,7 @@ WRITE8_MEMBER(ojankohs_state::ccasino_palette_w)
 {
 	int r, g, b;
 
-	/* get top 8 bits of the I/O port address */
-	offset = (offset << 8) | (m_maincpu->state_int(Z80_BC) >> 8);
+	offset = bitswap<11>(offset, 2, 1, 0, 15, 14, 13, 12, 11, 10, 9, 8);
 
 	m_paletteram[offset] = data;
 
@@ -270,6 +269,12 @@ VIDEO_START_MEMBER(ojankohs_state,ojankoy)
 //  m_colorram = std::make_unique<uint8_t[]>(0x1000);
 }
 
+VIDEO_START_MEMBER(ojankohs_state,ccasino)
+{
+	VIDEO_START_CALL_MEMBER(ojankoy);
+	m_paletteram.allocate(0x800);
+}
+
 VIDEO_START_MEMBER(ojankohs_state,ojankoc)
 {
 	m_screen->register_screen_bitmap(m_tmpbitmap);