DREAMNEOCD vs Geolith

DREAMNEOCD is a Sega Dreamcast emulator for Neo Geo CD games, including selfboot games. It can also be used through DreamShell with an SD card, without CDDA. The project was ported to Dreamcast in 2004 and its maker describes it as the first working Neo Geo CD emulator for the console. It is based on Foster's NeoCD/SDL; the README credits libSDL, using its sound component. To run, it needs a 512 KB system BIOS from an original Neo Geo CD console, named neocd.bin. The README warns that a smaller BIOS will not work with version 1.0 onward, and the repository cautions that the BIOS is copyrighted and users are not entitled to a copy unless they own an original Neo Geo CD console. The program is free, but the maker prohibits selling it and limits source-code and technical-knowledge reuse to noncommercial purposes. The repository lists a GPL-2.0 license. It does not support AES or MVS emulation, related SNK arcade games, netplay, or save states.

Geolith is a free emulator for the Neo Geo AES, MVS, CD, and CDZ. It supports commercially released AES, MVS, and CD games, and runs on Linux, macOS, BSD, and Windows. Cartridge systems accept TerraOnion .NEO files; CD systems use .bin/.cue and can optionally use .chd images. BIOS files from a recent MAME set are required, with the needed archives varying by system. Geolith synchronizes its CPUs with the video and sound systems, though video event timing is best effort and cycle-accurate rendering remains a longer-term goal. Settings include system and BIOS mode, region, free play, memory card options, palette, and aspect ratio. Supported inputs range from Neo Geo joysticks to a Mahjong Controller, four-player extension board, V-Liner, and the Irritating Maze trackball. The project was written for The Jolly Good API and can be used in multi-emulator frameworks or standalone binaries. It does not support dedicated JAMMA PCB systems or PAL mode; an early Stakes Winner prototype is also unsupported because required data is missing.