I was having a bit of a tricky time converting this rom to work with NeoDS, and I noticed 2 different people hijacked the NeoDS compatibility thread to ask the same question, so after figuring it out, I figured I'd explain what you need to do to get it to work. OK, here's the situation, you're trying to convert 'SNK Vs Capcom SVC Chaos Super Plus' with NeoDsConvert and it's just not working. Let's see what the problem might be... Using the info from \NeoDsConvert\neodrvr.cpp , make sure these are all there, and if you're using WinRAR, you can easily see the CRCs, so make sure theyre good. ROM_START( svcsplus ) /* bootleg */ "svc-p1sp.bin", 0x000000, 0x400000, CRC(2601902f) "svc-p2sp.bin", 0x400000, 0x400000, CRC(0ca13305) "svc-s1sp.bin", CRC(233d6439) "sm1.sm1", 0x00000, 0x20000, CRC(97cf998b) "svc-m1.bin", 0x20000, 0x10000, CRC(804328c3) "svc-v2.bin", 0x000000, 0x400000, CRC(b5097287) "svc-v1.bin", 0x400000, 0x400000, CRC(bd3a391f) "svc-v4.bin", 0x800000, 0x400000, CRC(33fc0b37) "svc-v3.bin", 0xc00000, 0x400000, CRC(aa9849a0) "svc-c1.bin", 0x0000000, 0x800000, CRC(a7826b89) "svc-c2.bin", 0x0000001, 0x800000, CRC(ed3c2089) "svc-c3.bin", 0x1000000, 0x800000, CRC(71ed8063) "svc-c4.bin", 0x1000001, 0x800000, CRC(250bde2d) "svc-c5.bin", 0x2000000, 0x800000, CRC(9817c082) "svc-c6.bin", 0x2000001, 0x800000, CRC(2bc0307f) "svc-c7.bin", 0x3000000, 0x800000, CRC(4358d7b9) "svc-c8.bin", 0x3000001, 0x800000, CRC(366deee5) ROM_END I had to add sm1.sm1, which is the BIOS file you'll find in NeoGeo.zip, I'm not sure if it needed to be in there, but it works, so it doesn't hurt to do it. And the tricky part was figuring out this... "Failed to open parent: svc", (here comes the excuse...) I havent really been playing my MAME or NEOGEO roms in quite a while, and was thinking 'PARENT' meaning 'parent folder', I wasn't thinking of 'parent ROM', which is what it means. So make sure you have the 'parent ROM', which is SVC.ZIP in the same folder. And thats about it. So to recap: Make sure your ROM is a valid MAME ROM, and the filename is correct, this one was svcsplus.zip. Make sure it contains the proper files, to double-check just open \NeoDsConvert\neodrvr.cpp, and Ctrl-F and look for the ROM name. Make sure the parent ROM is in the same folder, the parent ROM here was svc.zip. And that's that. This one runs great, slowing the CPU seems to speed up the game. And I should add, this one was converted with -bios1 parameter.