# Getting started - RetroBIOS

## What are BIOS files?

BIOS files are firmware dumps from original console hardware. Emulators need them to boot games for systems that relied on built-in software (PlayStation, Saturn, Dreamcast, etc.). Without the correct BIOS, the emulator either refuses to start the game or falls back to less accurate software emulation.

## Installation

Three ways to get BIOS files in place, from easiest to most manual.

### Option 1: the installer (recommended)

One command, nothing to clone. The bootstrap verifies `install.py` against the
SHA-256 embedded in it, then the installer detects the platform and its BIOS
directory, downloads only what is missing or incorrect, checks size and
SHA-256/SHA-1 before writing, and installs each file atomically.

```bash
# Linux / macOS / Steam Deck
curl -fsSL https://raw.githubusercontent.com/Abdess/retrobios/main/install.sh | sh

# Windows (PowerShell)
irm https://raw.githubusercontent.com/Abdess/retrobios/main/install.ps1 | iex
```

Running `install.py` directly works the same way and needs nothing beyond
Python 3.10+:

```bash
python install.py
```

Override detection when needed:

```bash
python install.py --platform retroarch --dest ~/custom/bios
python install.py --target switch      # keep only files for that hardware
python install.py --check              # verify existing files, download nothing
python install.py --list-platforms     # supported platforms and what was detected
python install.py --list-targets       # hardware targets for a platform
python install.py --jobs 4             # parallel downloads (default 8)
python install.py --verbose
python install.py --standalone-copies  # opt in to extra standalone-emulator paths
```

The default flow writes inside the detected platform tree only. Copies into
separate standalone-emulator directories are opt-in, so discovery cannot cause
unexpected writes elsewhere on the machine.
Entries the collection cannot satisfy are reported as safely omitted and the
run continues; the installer never substitutes a same-named file for one a
hash-verifying platform would reject.

Arguments pass through the one-liner too, which is how you target an SD card
mounted on another machine:

```bash
curl -fsSL https://raw.githubusercontent.com/Abdess/retrobios/main/install.sh \
  | sh -s -- --platform retroarch --dest /path/to/sdcard
```

### Option 2: download.sh (Linux/macOS, from a clone)

Downloads a whole pack rather than the missing files. Needs `curl` and `unzip`:

```bash
bash scripts/download.sh retroarch ~/RetroArch/system/
bash scripts/download.sh --list  # show available packs
```

### Option 3: manual download

1. Go to the [releases page](https://github.com/Abdess/retrobios/releases)
2. Download the ZIP pack for your platform
3. Extract to the BIOS directory listed below

Packs over 2 GB are split into numbered volumes (`.zip.001`, `.zip.002`).
Download every part and open the `.001` file with 7-Zip or PeaZip, which
extracts the whole set. See [Download](../which-pack.md) for the pack
variants and per-setup instructions.

## BIOS directory by platform

### RetroArch

RetroArch uses the `system_directory` setting in `retroarch.cfg`. Default locations:

| OS | Default path |
|----|-------------|
| Windows (installer) | `%APPDATA%\RetroArch\system\` |
| Windows (portable .7z) | `system\` next to `retroarch.exe` |
| Linux | `~/.config/retroarch/system/` |
| Linux (Flatpak) | `~/.var/app/org.libretro.RetroArch/config/retroarch/system/` |
| macOS | `~/Library/Application Support/RetroArch/system/` |
| Steam Deck (Flatpak) | `~/.var/app/org.libretro.RetroArch/config/retroarch/system/` |
| Android | `/storage/emulated/0/RetroArch/system/` |

Windows has two layouts because the installer stores its data under `%APPDATA%`
while the portable archive keeps everything inside the folder you extracted it
to. If both exist on the machine, the one RetroArch actually reads is the one
shown in the UI.

To check your actual path: open RetroArch, go to **Settings > Directory > System/BIOS**, or look for `system_directory` in `retroarch.cfg`.

### Batocera

```
/userdata/bios/
```

Accessible via network share at `\\BATOCERA\share\bios\` (Windows) or `smb://batocera/share/bios/` (macOS/Linux).

### Recalbox

```
/recalbox/share/bios/
```

Accessible via network share at `\\RECALBOX\share\bios\`.

### RetroBat

```
bios/
```

Relative to the RetroBat installation directory (e.g., `C:\RetroBat\bios\`).

### RetroDECK

```
~/retrodeck/bios/
```

On a MicroSD install the root moves, e.g. `/run/media/mmcblk0p1/retrodeck/bios/`.

The RetroDECK pack is the exception to "extract into the BIOS directory": its
entries already start with `bios/` (and one with `roms/`), so extract it into
`~/retrodeck/` and the files land in the right place. Extracting into
`~/retrodeck/bios/` would create `~/retrodeck/bios/bios/`.

### EmuDeck

```
Emulation/bios/
```

Located inside your Emulation folder. On Steam Deck, typically `~/Emulation/bios/`.

### Lakka

```
/storage/system/
```

Accessible via SSH or Samba.

### RetroPie

```
~/RetroPie/BIOS/
```

RetroPie is archived in this project: its configuration is kept and packs are
still built, but the upstream data is no longer scraped on a schedule. It
inherits RetroArch's file set, so the RetroArch pack applies as well.

### ROCKNIX

```
/storage/roms/bios/
```

Accessible via SSH or Samba, like Lakka.

### MiSTer FPGA

```
/media/fat/games/
```

Files go under the per-core subdirectory the MiSTer BIOS database declares
(e.g. `/media/fat/games/3DO/boot.rom`). Only the entries the BIOS database
lists with a download URL are in scope: the rest ship with the MiSTer
distribution and install themselves.

### BizHawk

```
Firmware/
```

Relative to the BizHawk installation directory.

### RomM

BIOS files live in the RomM library under `bios/{platform_slug}/`, one
subfolder per system, and are managed through the web interface. Check the
[RomM documentation](https://github.com/rommapp/romm) for setup details.

## Verifying your setup

`install.py --check` verifies an existing install without downloading anything.
For the full report, run `verify.py` from a clone of the repository:

```bash
python scripts/verify.py --platform retroarch
python scripts/verify.py --platform batocera
python scripts/verify.py --platform recalbox
```

The output shows each expected file with its status: `ok`, `missing`, or
`untested`. `untested` means the file is there but its hash is not the expected
one, which is how a wrong revision or a bad dump shows up.

Only hash-checking platforms can catch a wrong version: Batocera, RetroBat,
Recalbox, EmuDeck, RetroDECK, RomM, ROCKNIX and MiSTer FPGA compare MD5,
BizHawk compares SHA1. RetroArch, Lakka and RetroPie only check that the file
exists, so add `--verbose` there to compare against the emulator ground truth.

For a single system:

```bash
python scripts/verify.py --system sony-playstation
```

For a single emulator core:

```bash
python scripts/verify.py --emulator beetle_psx
```

See [Tools](tools.md) for the full CLI reference.

## Next steps

- [FAQ](faq.md) - common questions and troubleshooting
- [Tools](tools.md) - all available scripts and options
- [Architecture](architecture.md) - how the project works internally