The Card

omega-zero creates these folders on first boot. Nothing loose at the top of Games/, Saves/, Labels/ or States/ reaches the shelf.

Folder	Holds
Games/GBA, Games/GB, Games/GBC, Games/SNES, Games/PS1	Your legally obtained ROMs and disc images; see Systems for the files each takes. PlayStation games may also sit one folder down, as Games/PS1/<Game>/<Game>.cue
Labels/GBA, Labels/GB, Labels/GBC, Labels/SNES, Labels/PS1	Cart labels: a .png named after the ROM, for example Labels/GBA/Metroid Fusion.png for Games/GBA/Metroid Fusion.gba. A PlayStation game's label, under the game's name or its first disc's, goes on its first disc; each other disc has one under its own name, such as Labels/PS1/Final Fantasy VII (USA) (Disc 2).png
Saves/..., States/...	Battery saves and save states, per platform. A PlayStation game's memory card is its save, and Saves/PS1/<game>.disc says which disc is in the drive
BIOS	gba_bios.bin, gbc_bios.bin, gb_bios.bin for the boot animations, and a PlayStation BIOS such as scph5501.bin (all optional; see Systems)
Wallpapers	.png wallpapers for the shelf, see Shelf Background
Overlays/GBA, Overlays/GB, Overlays/GBC, Overlays/SNES, Overlays/PS1	Your Overlays
Config	Settings, wifi.conf with the Wi-Fi networks you have joined, your ScreenScraper account, and an optional theme.txt, see Shelf Background. playlists/PS1 holds the playlists omega-zero writes for PlayStation games on several discs
System	omega-zero itself, its cores and its licences. Replaced on every update

omega-zero can fetch labels itself over Wi-Fi; see Cart Labels. Per-cart shell colours go in Config/cart_shell.ini, which also picks a SNES cart's shape; see Systems.

At the root of the card, omega-zero.log holds the last session's log; see Troubleshooting.