SNK - Neo Geo AES / MVS (Geolith)¶

Background¶

Geolith is a highly accurate Neo Geo AES/MVS emulator written in ISO C11. Geolith takes a different approach to Neo Geo emulation than most existing emulators, aiming for a home-console-first experience and using single file ROMs (which never need to be updated) similar to a typical home console emulator. Despite the focus on the home experience, Geolith also fully supports arcade mode.

The Geolith core has been authored by

Rupert Carmichael (carmiker)

The Geolith core is licensed under

BSD-3-Clause

A summary of the licenses behind RetroArch and its cores can be found here.

BIOS¶

Geolith requires a BIOS.

Required or optional firmware files go in the frontend's system directory.

Attention

Geolith requires BIOS files to function. Place the following files in RetroArch's system directory:

Filename	Description	md5sum
aes.zip	Neo Geo AES BIOS - Required	ad9585c72130c56f04ae26aae87c289d
neogeo.zip	Neo Geo MVS BIOS - Required	00dad01abdbf8ea9e79ad2fe11bdb182

Extensions¶

Content that can be loaded by the Geolith core have the following file extensions:

.neo

Features¶

Frontend-level settings or features that the Geolith core respects.

Feature	Supported
Restart	✔
Screenshots	✔
Saves	✔
States	✔
Rewind	✔
Netplay	✔
Core Options	✔
RetroAchievements	✕
RetroArch Cheats	✕
Native Cheats	✕
Controls	✔
Remapping	✔
Multi-Mouse	✕
Rumble	✕
Sensors	✕
Camera	✕
Location	✕
Subsystem	✕
Softpatching	✔
Disk Control	✕
Username	✕
Language	✕
Crop Overscan	✔
LEDs	✕

Directories¶

The Geolith core's library name is 'Geolith'

The Geolith core saves/loads to/from these directories.

Frontend's Save directory

File	Description
*.nv	NVRAM save
*.mcr	Memory Card save
*.srm	Cartridge battery save

Frontend's State directory

File	Description
*.state#	State

Geometry and timing¶

The Geolith core's core provided FPS is 59.599484 for AES and 59.185606 for MVS
The Geolith core's core provided sample rate is 55943.49Hz for AES and 55555Hz for MVS
The Geolith core provides adjustable overscan masking and aspect ratio options

Core options¶

The Geolith core has the following options that can be tweaked from the core options menu. The default setting is bolded.

Settings with (Restart) means that core has to be closed for the new setting to be applied on next launch.

System Type (Restart) [geolith_system_type] (Neo Geo AES (Home Console)|Neo Geo MVS (Arcade)|Universe BIOS (Community-enhanced BIOS))

Specify the System Type: AES, MVS, or Universe BIOS System
Region (Restart) [geolith_region] (USA|Japan|Asia|Europe)

Specify the Region: USA, Japan, Asia, Europe
Setting Mode (Restart, DIP Switch) [geolith_settingmode] (Off|On)

Bring up the System ROM menu at boot on arcade systems
Four Player Mode (Restart, Asia/Japan MVS Only) [geolith_4player] (Off|On)

Set Four Player (dual MVS cabinet) mode for Asia/Japan MVS systems, for use with Kizuna Encounter or homebrew with four player support
Freeplay (DIP Switch) [geolith_freeplay] (Off|On)

Play MVS games without the need to insert coins
Mask Overscan (Top) [geolith_overscan_t] (16|12|8|4|0)

Mask off pixels hidden by a bezel or border on original CRTs (top)
Mask Overscan (Bottom) [geolith_overscan_b] (16|12|8|4|0)

Mask off pixels hidden by a bezel or border on original CRTs (bottom)
Mask Overscan (Left) [geolith_overscan_l] (16|12|8|4|0)

Mask off pixels hidden by a bezel or border on original CRTs (left)
Mask Overscan (Right) [geolith_overscan_r] (16|12|8|4|0)

Mask off pixels hidden by a bezel or border on original CRTs (right)
Aspect Ratio [geolith_aspect] (Perfectly Square Pixels (1:1 PAR)|Ostensibly Accurate NTSC Aspect Ratio (45:44 PAR)|Very Traditional NTSC Aspect Ratio (4:3 DAR))

Set the Aspect Ratio
Sprites-per-line limit (Hack) [geolith_sprlimit] (Hardware Accurate (96)|Double (192)|Triple (288)|MAX 381 MEGA PRO-GEAR SPEC)

Set the sprites-per-line limit - increasing causes glitches in some games
Overclocking (Hack) [geolith_oc] (Off|On)

Annihilate your accuracy with The 24MHz Shock - expect glitches. DO NOT USE THIS FOR ALL GAMES, enable only for specific cases with major slowdown.