diff --git a/src/mame/drivers/vigilant.cpp b/src/mame/drivers/vigilant.cpp
index 9f18d577e2e..239a7c85a53 100644
--- a/src/mame/drivers/vigilant.cpp
+++ b/src/mame/drivers/vigilant.cpp
@@ -1031,7 +1031,7 @@ ROM_START( buccanrs )
 	ROM_LOAD( "2.u74",  0x00000, 0x10000, CRC(36ee1dac) SHA1(6dfd2a885c0b1c9347abc4b204ade66551c4b404) )
 
 	ROM_REGION( 0x400, "proms", 0 )
-	ROM_LOAD( "prom1.u54",  0x0000, 0x0100, CRC(c324835e) SHA1(cf6ffe38523badfda211d341410e93e647de87a9) )
+	ROM_LOAD( "prom1.u54",  0x0000, 0x0100, CRC(c324835e) SHA1(cf6ffe38523badfda211d341410e93e647de87a9) ) // == ic52 video timing prom from vigilante
 	ROM_LOAD( "prom4.u79",  0x0100, 0x0100, CRC(e6506ef4) SHA1(079841da7640b14d94aaaeb572bf018932b58293) )
 	ROM_LOAD( "prom3.u88",  0x0200, 0x0100, CRC(b43d094f) SHA1(2bed4892d8a91d7faac5a07bf858d9294eb30606) )
 	ROM_LOAD( "prom2.u99",  0x0300, 0x0100, CRC(e0aa8869) SHA1(ac8bdfeba69420ba56ec561bf3d0f1229d02cea2) )
@@ -1070,7 +1070,7 @@ ROM_START( buccanrsa )
 	ROM_LOAD( "2.u74",  0x00000, 0x10000, CRC(36ee1dac) SHA1(6dfd2a885c0b1c9347abc4b204ade66551c4b404) )
 
 	ROM_REGION( 0x400, "proms", 0 )
-	ROM_LOAD( "prom1.u54",  0x0000, 0x0100, CRC(c324835e) SHA1(cf6ffe38523badfda211d341410e93e647de87a9) )
+	ROM_LOAD( "prom1.u54",  0x0000, 0x0100, CRC(c324835e) SHA1(cf6ffe38523badfda211d341410e93e647de87a9) ) // == ic52 video timing prom from vigilante
 	ROM_LOAD( "prom4.u79",  0x0100, 0x0100, CRC(e6506ef4) SHA1(079841da7640b14d94aaaeb572bf018932b58293) )
 	ROM_LOAD( "prom3.u88",  0x0200, 0x0100, CRC(b43d094f) SHA1(2bed4892d8a91d7faac5a07bf858d9294eb30606) )
 	ROM_LOAD( "prom2.u99",  0x0300, 0x0100, CRC(e0aa8869) SHA1(ac8bdfeba69420ba56ec561bf3d0f1229d02cea2) )