SNK - Neo Geo AES / MVS (Geolith) help!

so the new core snk (Geolith) load only .neo roms ???

i dont get it

where get this .neo files

As with all things libretro, we assume you dump your own games in accordance with your local laws.

These are the same ROMs used by the TerraOnion NeoSD, and I believe they’re the basis for MiSTer’s NeoGeo set, as well.

I didn’t know about this core. Any advantage to Neo Geo with the other cores?

it’s apparently very accurate and the ROMs don’t change. It acts like a regular console core instead of doing all of the weird arcade stuff.

It should support all of the savestate shenanigans like runahead and netplay, as well.

Be aware, though, it depends on CPU cache(?) pretty heavily, such that even very good computers from a few years ago (e.g., the author’s 2015 macbook pro) can’t run it full speed, while even relatively bad ones that are more recent (such as some SBC he tests on) can.


Just tried, I am on a “old” desktop with a i5 6400 (2015, I think), and it runs very well (in garou mark of the wolf with FF goes up to 220 fps with a shader on top).

One thing, I really tried but could not find so I just renamed from fbneo set and it actually worked. :nerd_face:

I also tried to make a playlist but there is no “proper” system name to chose from.

EDIT: just for the sake of it I tried same game in fbneo and indeed FPS gets to around 700, so yeah 3 times slower but still good performance with plenty headroom


Yes, I’m still working on the database. Once it’s finished that will be another benefit to this core: compatibility with the regular scanner.

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that’s great! I really wish that also fbneo had a similar simple roms system.

Do these roms work if they are zipped?

Also, have you noticed any difference in the way the games work? Maybe some known bug that’s fixed because of the higher accuracy? AFAIK, both MAME and FBNeo play these games pretty accurately so i wonder if there’s really a benefit here.

Edit: I’m trying to make this core work to no avail. I placed the in the system folder, load a .neo rom zipped or not and it just crashes to the menu.

Edit: Apparently, the instructions in the github page are wrong. It says “BIOS files from a recent MAME set are required” but the MAME neogeo bios doesn’t have the required files inside the zip. I had to use one from a different source. Also, naming it “” won’t work either. It has to be renamed to “”.

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hi you need also rename to that works

Ok i did some more testings.

What bios you need depends on what you pick in the core options. By default it’s set to AES, so it needs the If you change it to MVS, it will need the So you need two separate files for both modes to work. The files required for the AES mode are not included in the from the MAME romset. As i said, i had to find those files elsewhere.

The MVS mode does load with the MAME bios but it gets stuck on the green garbled screen before initialization. I haven’t managed to make it go further with any bios.


Have you checked the documentation for it? It includes some BIOS checksums and names.

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Same here. With from MAME in MVS mode it would run. A simple renaming to is not enough. I copied the from my FB Neo installation and renamed it to, which works to play in AES mode now. The MD5 checksum is 67682655fa5fb32831e28429643e26c7 and includes neo-epo.bin neo-po.bin neodebug.bin neopen.sp1 .

This is an amazing core! I read Geolith started out as a fork of GnGeo (just like FB Neo started as a fork of FB Alpha), which I ignored previously. Separating AES roms from arcade was always an important priority for me. And having a non changing home console setup (Edit: , that also is more accurate,~ I’m guilty of these statements as well) is perfect. Big thank you to hunterk and everyone else working on this!

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FBNeo has 1 neogeo romset containing both mvs and aes bioses, while MAME has separate romsets for this (aes for aes bioses and neogeo for mvs bioses, i think unibioses are bundled with the mvs bioses).

Not convinced by the “more accurate” thingy :

The longer term goal is to have completely cycle accurate video rendering, but for now, things are emulated accurately enough that all games are fully playable with only very minor differences from real hardware, and no known major bugs.

Meaning they currently aren’t ?

Well, i’d say MAME is already plenty accurate for neogeo emulation. By default, FBNeo doesn’t draw neogeo line by line so it’s technically inaccurate (we enable our “line by line” drawing mode only if the game has issues with our normal drawing mode).

Accuracy is always such a murky claim anyway. The perception of accuracy has more to do with how often the dev/team says the word “accuracy” than any objective measures (aside from the occasional automated test ROM shootout or high-profile demo, like Overdrive II, which even that stuff can be misleading).

Rather than looking at it as “someone should use this core instead of MAME/FBNeo due to accuracy,” I think the proper outlook is “a user won’t have a worse experience with this core than with the others due to lack of accuracy.”

For that matter, I’ve never had any problems with FBNeo’s neogeo emulation, so even if it’s technically less accurate than MAME, I’d never know it.


Most neogeo games don’t need to be drawn line by line, doing so nonetheless is costlier emulation for the same result, which is perfectly fine if your main goal is to document a machine.


BTW. MAME has an

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That’s the problem though, how would you know there are accuracy problems in a game if you don’t have the original hardware to compare it to?

Accuracy issues don’t always manifest as obvious graphics/sound glitches. Sometimes they are so subtle that you have no idea you are affected by them while playing. Maybe a game you are playing runs at the wrong speed. Maybe it’s missing effects instead of displaying them wrong. Maybe the music instruments are wrong but you wouldn’t know if you haven’t listened to the original. Maybe the game plays completely wrong but again, you have to have a reference to know this.

That’s why i’m taking accuracy claims very seriously. When someone says X emulator is more accurate than Y, i’m going to use X because that means the chances my experience with any game is the intended one are higher. I don’t like the idea of experiencing a game in a way that’s not intended, even when there aren’t any obvious issues and i enjoy my time with it.

Amazing! I didn’t think of checking that. The version from MAME matches the exact MD5 checksum listed in the documentation: I’m using that one now.

The is not included in the “device/bios” romset of MAME, which is supposed to be all the bios files but not the games. I assumed i would find it there so i thought there isn’t one. The complete romset has it though, yes. Not sure if this is intentional or an error.

That takes care of AES mode.

Have you managed to make MVS mode work? What bios are you using for it? The one from MAME loads it but gets stuck at the green garble initialization screen for me.