diff --git a/src/mame/concept/concept.cpp b/src/mame/concept/concept.cpp
index 99e0a8a6e1169..e7ea643da4e46 100644
--- a/src/mame/concept/concept.cpp
+++ b/src/mame/concept/concept.cpp
@@ -196,23 +196,26 @@ ROM_START( concept )
 	ROM_REGION16_BE(0x100000,"maincpu",0)   /* 68k rom and ram */
 
 	// concept boot ROM
-	ROM_SYSTEM_BIOS(0, "lvl8", "Level 8" )  // v0?
-	ROMX_LOAD("bootl08h", 0x010000, 0x1000, CRC(ee479f51) SHA1(b20ba18564672196076e46507020c6d69a640a2f), ROM_BIOS(0) | ROM_SKIP(1))
-	ROMX_LOAD("bootl08l", 0x010001, 0x1000, CRC(acaefd07) SHA1(de0c7eaacaf4c0652aa45e523cebce2b2993c437), ROM_BIOS(0) | ROM_SKIP(1))
+	ROM_DEFAULT_BIOS("v17")
+
+	ROM_SYSTEM_BIOS(0, "lvl6", "Level 6" )  // v0?
+	ROMX_LOAD("cc06h", 0x010000, 0x1000, CRC(66b6b259) SHA1(1199a38ef3e94f695e8da6a7c80c6432da3cb80c), ROM_BIOS(0) | ROM_SKIP(1))
+	ROMX_LOAD("cc06l", 0x010001, 0x1000, CRC(600940d3) SHA1(c3278bf23b3b1c35ea1e3da48a05e877862a8345), ROM_BIOS(0) | ROM_SKIP(1))
 
 	ROM_SYSTEM_BIOS(1, "lvl7", "Level 7" )  // v0? v1?
 	ROMX_LOAD("cc07h", 0x010000, 0x1000, CRC(455abac8) SHA1(b12e1580220242d34eafed1b486cebd89e823c8b), ROM_BIOS(1) | ROM_SKIP(1))
 	ROMX_LOAD("cc07l", 0x010001, 0x1000, CRC(107a3830) SHA1(0ea12ef13b0d11fcd83b306b3a1bb8014ba910c0), ROM_BIOS(1) | ROM_SKIP(1))
 
-	ROM_SYSTEM_BIOS(2, "lvl6", "Level 6" )  // v0?
-	ROMX_LOAD("cc06h", 0x010000, 0x1000, CRC(66b6b259) SHA1(1199a38ef3e94f695e8da6a7c80c6432da3cb80c), ROM_BIOS(2) | ROM_SKIP(1))
-	ROMX_LOAD("cc06l", 0x010001, 0x1000, CRC(600940d3) SHA1(c3278bf23b3b1c35ea1e3da48a05e877862a8345), ROM_BIOS(2) | ROM_SKIP(1))
+	ROM_SYSTEM_BIOS(2, "lvl8", "Level 8" )  // v0?
+	ROMX_LOAD("bootl08h", 0x010000, 0x1000, CRC(ee479f51) SHA1(b20ba18564672196076e46507020c6d69a640a2f), ROM_BIOS(2) | ROM_SKIP(1))
+	ROMX_LOAD("bootl08l", 0x010001, 0x1000, CRC(acaefd07) SHA1(de0c7eaacaf4c0652aa45e523cebce2b2993c437), ROM_BIOS(2) | ROM_SKIP(1))
+
+	// the 1.7 ROM (at least) works with Corvus OS 1.2
+	ROM_SYSTEM_BIOS(3, "v17", "Version 1 Level 7" )
+	ROMX_LOAD("ccb17h.bin", 0x010000, 0x1000, CRC(6dd9718f) SHA1(7427d218dc13b1b319866d5a1e59e152fab082b3), ROM_BIOS(3) | ROM_SKIP(1))
+	ROMX_LOAD("ccb17l.bin", 0x010001, 0x1000, CRC(107a3830) SHA1(0ea12ef13b0d11fcd83b306b3a1bb8014ba910c0), ROM_BIOS(3) | ROM_SKIP(1))
 
 #if 0
-	// version 1 lvl 7 release
-	ROM_LOAD16_BYTE("bootl17h", 0x010000, 0x1000, CRC(6dd9718f))    // where does this come from?
-	ROM_LOAD16_BYTE("bootl17l", 0x010001, 0x1000, CRC(107a3830) SHA1(0ea12ef13b0d11fcd83b306b3a1bb8014ba910c0))
-#elif 0
 	// version $F lvl 8 (development version found on a floppy disk along with
 	// the source code)
 	ROM_LOAD16_WORD("cc.prm", 0x010000, 0x2000, CRC(b5a87dab) SHA1(0da59af6cfeeb38672f71731527beac323d9c3d6))