diff --git a/src/mame/drivers/chihiro.cpp b/src/mame/drivers/chihiro.cpp
index 29508ea9a63..41197649f34 100644
--- a/src/mame/drivers/chihiro.cpp
+++ b/src/mame/drivers/chihiro.cpp
@@ -755,7 +755,7 @@ int ohci_hlean2131qc_device::handle_nonstandard_request(int endpoint, USBSetupPa
 	}
 	if (setup->bRequest == 0x19) // 19 used to receive packet, 20 to send ?
 	{
-		// amount to transfer
+		// amount to transfer with endpoint 4
 		endpoints[endpoint].buffer[5] = 20 >> 8;
 		endpoints[endpoint].buffer[4] = (20 & 0xff);
 		endpoints[4].remain = 20;
@@ -1091,6 +1091,7 @@ WRITE32_MEMBER(chihiro_state::mediaboard_w)
 
 static ADDRESS_MAP_START(chihiro_map, AS_PROGRAM, 32, chihiro_state)
 	AM_IMPORT_FROM(xbox_base_map)
+	AM_RANGE(0xff000000, 0xff07ffff) AM_ROM AM_REGION("bios", 0) AM_MIRROR(0x00f80000)
 ADDRESS_MAP_END
 
 static ADDRESS_MAP_START(chihiro_map_io, AS_IO, 32, chihiro_state)
@@ -1163,7 +1164,7 @@ MACHINE_CONFIG_END
 		ROMX_LOAD(name, offset, length, hash, ROM_BIOS(bios+1)) /* Note '+1' */
 
 #define CHIHIRO_BIOS \
-	ROM_REGION( 0x100000, "bios", 0) \
+	ROM_REGION( 0x80000, "bios", 0) \
 	ROM_SYSTEM_BIOS( 0, "bios0", "Chihiro Bios" ) \
 	ROM_LOAD_BIOS( 0,  "chihiro_xbox_bios.bin", 0x000000, 0x80000, CRC(66232714) SHA1(b700b0041af8f84835e45d1d1250247bf7077188) ) \
 	ROM_REGION( 0x200000, "mediaboard", 0) \
diff --git a/src/mame/drivers/xbox.cpp b/src/mame/drivers/xbox.cpp
index eda30d3003c..c49dde71548 100644
--- a/src/mame/drivers/xbox.cpp
+++ b/src/mame/drivers/xbox.cpp
@@ -59,6 +59,7 @@ void xbox_state::video_start()
 
 static ADDRESS_MAP_START(xbox_map, AS_PROGRAM, 32, xbox_state)
 	AM_IMPORT_FROM(xbox_base_map)
+	AM_RANGE(0xff000000, 0xff0fffff) AM_ROM AM_REGION("bios", 0) AM_MIRROR(0x00f00000)
 ADDRESS_MAP_END
 
 static ADDRESS_MAP_START(xbox_map_io, AS_IO, 32, xbox_state)
diff --git a/src/mame/machine/xbox.cpp b/src/mame/machine/xbox.cpp
index 7479aec05a2..e4cdcee007b 100644
--- a/src/mame/machine/xbox.cpp
+++ b/src/mame/machine/xbox.cpp
@@ -2605,7 +2605,6 @@ ADDRESS_MAP_START(xbox_base_map, AS_PROGRAM, 32, xbox_base_state)
 	AM_RANGE(0xfe800000, 0xfe87ffff) AM_READWRITE(audio_apu_r, audio_apu_w)
 	AM_RANGE(0xfec00000, 0xfec00fff) AM_READWRITE(audio_ac93_r, audio_ac93_w)
 	AM_RANGE(0xfef00000, 0xfef003ff) AM_READWRITE(network_r, network_w)
-	AM_RANGE(0xff000000, 0xff0fffff) AM_ROM AM_REGION("bios", 0) AM_MIRROR(0x00f80000)
 ADDRESS_MAP_END
 
 ADDRESS_MAP_START(xbox_base_map_io, AS_IO, 32, xbox_base_state)