diff --git a/src/devices/bus/amiga/zorro/a590.cpp b/src/devices/bus/amiga/zorro/a590.cpp
index 6971ee531a7..34279eda45e 100644
--- a/src/devices/bus/amiga/zorro/a590.cpp
+++ b/src/devices/bus/amiga/zorro/a590.cpp
@@ -136,36 +136,48 @@ ROM_START( dmac_hdc )
 	ROM_REGION16_BE(0x8000, "bootrom", 0)
 	ROM_DEFAULT_BIOS("v70")
 
-	ROM_SYSTEM_BIOS(0, "v60", "Version 6.0")
-	ROMX_LOAD("390388-03.u13", 0x0000, 0x2000, CRC(2e77bbff) SHA1(8a098845068f32cfa4d34a278cd290f61d35a52c), ROM_SKIP(1) | ROM_BIOS(1))
-	ROMX_LOAD("390389-03.u12", 0x0001, 0x2000, CRC(b0b8cf24) SHA1(fcf4017505f4d441814b45d559c19eab43816b30), ROM_SKIP(1) | ROM_BIOS(1))
-	ROMX_LOAD("390388-03.u13", 0x4000, 0x2000, CRC(2e77bbff) SHA1(8a098845068f32cfa4d34a278cd290f61d35a52c), ROM_SKIP(1) | ROM_BIOS(1))
-	ROMX_LOAD("390389-03.u12", 0x4001, 0x2000, CRC(b0b8cf24) SHA1(fcf4017505f4d441814b45d559c19eab43816b30), ROM_SKIP(1) | ROM_BIOS(1))
+	ROM_SYSTEM_BIOS(0, "v46", "Version 4.6") // a590 only?
+	ROMX_LOAD("390389-02.u13", 0x0000, 0x2000, NO_DUMP, ROM_SKIP(1) | ROM_BIOS(1)) // checksum-16: d703
+	ROMX_LOAD("390388-02.u12", 0x0001, 0x2000, NO_DUMP, ROM_SKIP(1) | ROM_BIOS(1)) // checksum-16: e7e4
+	ROMX_LOAD("390389-02.u13", 0x4000, 0x2000, NO_DUMP, ROM_SKIP(1) | ROM_BIOS(1))
+	ROMX_LOAD("390388-02.u12", 0x4001, 0x2000, NO_DUMP, ROM_SKIP(1) | ROM_BIOS(1))
+
+	ROM_SYSTEM_BIOS(1, "v592", "Version 5.92") // a2091 only?
+	ROMX_LOAD("390508-02.u13", 0x0000, 0x2000, NO_DUMP, ROM_SKIP(1) | ROM_BIOS(2)) // checksum-16: ?
+	ROMX_LOAD("390509-02.u12", 0x0001, 0x2000, NO_DUMP, ROM_SKIP(1) | ROM_BIOS(2)) // checksum-16: 288c
+	ROMX_LOAD("390508-02.u13", 0x4000, 0x2000, NO_DUMP, ROM_SKIP(1) | ROM_BIOS(2))
+	ROMX_LOAD("390509-02.u12", 0x4001, 0x2000, NO_DUMP, ROM_SKIP(1) | ROM_BIOS(2))
+
+	ROM_SYSTEM_BIOS(2, "v60", "Version 6.0") // a590 only?
+	ROMX_LOAD("390389-03.u13", 0x0000, 0x2000, CRC(2e77bbff) SHA1(8a098845068f32cfa4d34a278cd290f61d35a52c), ROM_SKIP(1) | ROM_BIOS(3)) // checksum-16: cbe8 (ok)
+	ROMX_LOAD("390388-03.u12", 0x0001, 0x2000, CRC(b0b8cf24) SHA1(fcf4017505f4d441814b45d559c19eab43816b30), ROM_SKIP(1) | ROM_BIOS(3)) // checksum-16: dfa0 (ok)
+	ROMX_LOAD("390389-03.u13", 0x4000, 0x2000, CRC(2e77bbff) SHA1(8a098845068f32cfa4d34a278cd290f61d35a52c), ROM_SKIP(1) | ROM_BIOS(3))
+	ROMX_LOAD("390388-03.u12", 0x4001, 0x2000, CRC(b0b8cf24) SHA1(fcf4017505f4d441814b45d559c19eab43816b30), ROM_SKIP(1) | ROM_BIOS(3))
 
 	// changelog v6.1: prevent accesses to location 0 by application programs
-	ROM_SYSTEM_BIOS(1, "v61", "Version 6.1")
-	ROMX_LOAD("390721-01.u13", 0x0000, 0x2000, CRC(00dbf615) SHA1(503940d04fb3b49eaa61100fd3a487018b35e25a), ROM_SKIP(1) | ROM_BIOS(2))
-	ROMX_LOAD("390722-01.u12", 0x0001, 0x2000, CRC(c460cfdb) SHA1(0de457daec3b84f75e8fb344defe24ce56cda3e0), ROM_SKIP(1) | ROM_BIOS(2))
-	ROMX_LOAD("390721-01.u13", 0x4000, 0x2000, CRC(00dbf615) SHA1(503940d04fb3b49eaa61100fd3a487018b35e25a), ROM_SKIP(1) | ROM_BIOS(2))
-	ROMX_LOAD("390722-01.u12", 0x4001, 0x2000, CRC(c460cfdb) SHA1(0de457daec3b84f75e8fb344defe24ce56cda3e0), ROM_SKIP(1) | ROM_BIOS(2))
+	ROM_SYSTEM_BIOS(3, "v61", "Version 6.1")
+	ROMX_LOAD("390721-01.u13", 0x0000, 0x2000, CRC(00dbf615) SHA1(503940d04fb3b49eaa61100fd3a487018b35e25a), ROM_SKIP(1) | ROM_BIOS(4)) // checksum-16: f4b8 (ok)
+	ROMX_LOAD("390722-01.u12", 0x0001, 0x2000, CRC(c460cfdb) SHA1(0de457daec3b84f75e8fb344defe24ce56cda3e0), ROM_SKIP(1) | ROM_BIOS(4)) // checksum-16: 088b (ok)
+	ROMX_LOAD("390721-01.u13", 0x4000, 0x2000, CRC(00dbf615) SHA1(503940d04fb3b49eaa61100fd3a487018b35e25a), ROM_SKIP(1) | ROM_BIOS(4))
+	ROMX_LOAD("390722-01.u12", 0x4001, 0x2000, CRC(c460cfdb) SHA1(0de457daec3b84f75e8fb344defe24ce56cda3e0), ROM_SKIP(1) | ROM_BIOS(4))
 
 	// changelog v6.6: fixes dual SCSI problems with the wd33c93a controller
-	ROM_SYSTEM_BIOS(2, "v66", "Version 6.6")
-	ROMX_LOAD("390721-02.u13", 0x0000, 0x2000, CRC(c0871d25) SHA1(e155f18abb90cf820589c15e70559d3b6b391af8), ROM_SKIP(1) | ROM_BIOS(3))
-	ROMX_LOAD("390722-02.u12", 0x0001, 0x2000, CRC(e536bbb2) SHA1(fd7f8a6da18c1b02d07eb990c2467a24183ede12), ROM_SKIP(1) | ROM_BIOS(3))
-	ROMX_LOAD("390721-02.u13", 0x4000, 0x2000, CRC(c0871d25) SHA1(e155f18abb90cf820589c15e70559d3b6b391af8), ROM_SKIP(1) | ROM_BIOS(3))
-	ROMX_LOAD("390722-02.u12", 0x4001, 0x2000, CRC(e536bbb2) SHA1(fd7f8a6da18c1b02d07eb990c2467a24183ede12), ROM_SKIP(1) | ROM_BIOS(3))
+	ROM_SYSTEM_BIOS(4, "v66", "Version 6.6")
+	ROMX_LOAD("390721-02.u13", 0x0000, 0x2000, CRC(c0871d25) SHA1(e155f18abb90cf820589c15e70559d3b6b391af8), ROM_SKIP(1) | ROM_BIOS(5)) // checksum-16: d464 (ok)
+	ROMX_LOAD("390722-02.u12", 0x0001, 0x2000, CRC(e536bbb2) SHA1(fd7f8a6da18c1b02d07eb990c2467a24183ede12), ROM_SKIP(1) | ROM_BIOS(5)) // checksum-16: f929 (ok)
+	ROMX_LOAD("390721-02.u13", 0x4000, 0x2000, CRC(c0871d25) SHA1(e155f18abb90cf820589c15e70559d3b6b391af8), ROM_SKIP(1) | ROM_BIOS(5))
+	ROMX_LOAD("390722-02.u12", 0x4001, 0x2000, CRC(e536bbb2) SHA1(fd7f8a6da18c1b02d07eb990c2467a24183ede12), ROM_SKIP(1) | ROM_BIOS(5))
 
 	// final Commodore released version
-	ROM_SYSTEM_BIOS(3, "v70", "Version 7.0")
-	ROMX_LOAD("390721-03.u13", 0x0000, 0x2000, CRC(2942747a) SHA1(dbd7648e79c753337ff3e4f491de224bf05e6bb6), ROM_SKIP(1) | ROM_BIOS(4))
-	ROMX_LOAD("390722-03.u12", 0x0001, 0x2000, CRC(a9ccffed) SHA1(149f5bd52e2d29904e3de483b9ad772448e9278e), ROM_SKIP(1) | ROM_BIOS(4))
-	ROMX_LOAD("390721-03.u13", 0x4000, 0x2000, CRC(2942747a) SHA1(dbd7648e79c753337ff3e4f491de224bf05e6bb6), ROM_SKIP(1) | ROM_BIOS(4))
-	ROMX_LOAD("390722-03.u12", 0x4001, 0x2000, CRC(a9ccffed) SHA1(149f5bd52e2d29904e3de483b9ad772448e9278e), ROM_SKIP(1) | ROM_BIOS(4))
+	ROM_SYSTEM_BIOS(5, "v70", "Version 7.0") // also seen with -07
+	ROMX_LOAD("390721-04.u13", 0x0000, 0x2000, CRC(2942747a) SHA1(dbd7648e79c753337ff3e4f491de224bf05e6bb6), ROM_SKIP(1) | ROM_BIOS(6)) // checksum-16: 081c (ok)
+	ROMX_LOAD("390722-04.u12", 0x0001, 0x2000, CRC(a9ccffed) SHA1(149f5bd52e2d29904e3de483b9ad772448e9278e), ROM_SKIP(1) | ROM_BIOS(6)) // checksum-16: 3ef2 (ok)
+	ROMX_LOAD("390721-04.u13", 0x4000, 0x2000, CRC(2942747a) SHA1(dbd7648e79c753337ff3e4f491de224bf05e6bb6), ROM_SKIP(1) | ROM_BIOS(6))
+	ROMX_LOAD("390722-04.u12", 0x4001, 0x2000, CRC(a9ccffed) SHA1(149f5bd52e2d29904e3de483b9ad772448e9278e), ROM_SKIP(1) | ROM_BIOS(6))
 
 	// third-party upgrade ROM, requires a small ROM adapter pcb
-	ROM_SYSTEM_BIOS(4, "g614", "Guru-ROM 6.14")
-	ROMX_LOAD("gururom_v614.bin", 0x0000, 0x8000, CRC(04e52f93) SHA1(6da21b6f5e8f8837d64507cd8a4d5cdcac4f426b), ROM_GROUPWORD | ROM_BIOS(5))
+	ROM_SYSTEM_BIOS(6, "g614", "Guru-ROM 6.14")
+	ROMX_LOAD("gururom_v614.bin", 0x0000, 0x8000, CRC(04e52f93) SHA1(6da21b6f5e8f8837d64507cd8a4d5cdcac4f426b), ROM_GROUPWORD | ROM_BIOS(7))
 
 	// pal16l8a
 	ROM_REGION(0x104, "ram_controller", 0)