diff --git a/src/mame/drivers/hng64.cpp b/src/mame/drivers/hng64.cpp
index 255f4cfbd72..d4793f241e2 100644
--- a/src/mame/drivers/hng64.cpp
+++ b/src/mame/drivers/hng64.cpp
@@ -1573,7 +1573,11 @@ MACHINE_CONFIG_END
 	ROM_REGION( 0x0100000, "user2", 0 ) /* KL5C80 BIOS */ \
 	ROM_LOAD ( "from1.bin", 0x000000, 0x080000,  CRC(6b933005) SHA1(e992747f46c48b66e5509fe0adf19c91250b00c7) ) \
 	ROM_REGION( 0x0100000, "fpga", 0 ) /* FPGA data  */ \
-	ROM_LOAD ( "rom1.bin",  0x000000, 0x01ff32,  CRC(4a6832dc) SHA1(ae504f7733c2f40450157cd1d3b85bc83fac8569) )
+	ROM_LOAD ( "rom1.bin",  0x000000, 0x01ff32,  CRC(4a6832dc) SHA1(ae504f7733c2f40450157cd1d3b85bc83fac8569) ) \
+	ROM_REGION( 0x08000, "iomcu", 0 ) /* unknown I/O MCU, might be Shooting type, came from recycled OTP chip sample, not a HNG64 board. */ \
+									  /* "64Bit I/O Controller Ver 1.0 1997.06.29(C)SNK" internal ID string */ \
+	ROM_LOAD ( "tmp87ph40an.bin",  0x000000, 0x08000,  CRC(b70df21f) SHA1(5b742e8a0bbf4c0ae4f4398d34c7058fb24acc92) )
+
 
 ROM_START( hng64 )
 	/* BIOS */