diff --git a/core/hw/naomi/naomi_cart.h b/core/hw/naomi/naomi_cart.h
index d05f57af4..e27065f37 100644
--- a/core/hw/naomi/naomi_cart.h
+++ b/core/hw/naomi/naomi_cart.h
@@ -35,10 +35,11 @@ struct RomBootID
 	u32  testPC;		// test mode entry point
 	u8   country;		// supported regions bitmap
 	u8   cabinet;		// supported # of players bitmap: b0 1 player, b1 2 players, ...
-	u8   resolution;	// 0: 31kHz, 1: 15kHz
-	u8   vertical;		// b0: horizontal mode, b1: vertical mode
+	u8   resolution;	// 0: 31kHz, 1: 15kHz, other: no check
+	u8   vertical;		// 1: horizontal mode, 2: vertical mode, other: no check
 	u8   serialID;		// if 1, check the ROM/DIMM board serial# eeprom
-	u8   _res[211];		// _res[210]: if 0xFF then the header is unencrypted. if not then the header is encrypted starting at offset 0x010.
+	u8   serviceMode;	// 0: common, 1: individual, other: use configured setting
+	u8   _res[210];		// _res[210]: if 0xFF then the header is unencrypted. if not then the header is encrypted starting at offset 0x010.
 
 	// Note: this structure is copied to system RAM by the BIOS at location 0c01f400
 };
diff --git a/core/hw/naomi/naomi_flashrom.cpp b/core/hw/naomi/naomi_flashrom.cpp
index 0a8ee292e..a55e7f5e6 100644
--- a/core/hw/naomi/naomi_flashrom.cpp
+++ b/core/hw/naomi/naomi_flashrom.cpp
@@ -195,19 +195,19 @@ void configure_naomi_eeprom(const RomBootID *bootId)
 {
 	initEeprom(bootId);
 	// Horizontal / vertical screen orientation
-	if (bootId->vertical & 2)
+	if (bootId->vertical == 2)
 	{
 		NOTICE_LOG(NAOMI, "EEPROM: vertical monitor orientation");
 		write_naomi_eeprom(2, readEeprom(2) | 1);
 		config::Rotate90.override(true);
 	}
-	else if (bootId->vertical & 1)
+	else if (bootId->vertical == 1)
 	{
 		NOTICE_LOG(NAOMI, "EEPROM: horizontal monitor orientation");
 		write_naomi_eeprom(2, readEeprom(2) & ~1);
 	}
 	// Number of players
-	if (bootId->cabinet != 0)
+	if (bootId->cabinet != 0 && bootId->cabinet < 0x10)
 	{
 		int nPlayers = readEeprom(8) >> 4;	// 0 to 3
 		if (!(bootId->cabinet & (1 << nPlayers)))