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Deecy
What it is
Deecy is an experimental, open-source Dreamcast emulator written in Zig for Windows and Linux. Its command-line interface loads .gdi, .cdi, and .chd disc files, but setup requires BIOS and flash dumps named dc_boot.bin and dc_flash.bin in the data folder. Users also choose the folder containing their disc images. Controllers should be detected and mapped automatically; manual guest-port assignment and customizable keyboard bindings are available. The emulator has four save-state slots and four matching load-state slots, along with fullscreen toggling and an unlimited emulation-speed mode. On Linux, the optional --scif option pipes a serial port to /tmp/deecy/scif for dcload-serial prototyping. DreamPicoPort support is an optional build dependency and can be disabled at build time. Deecy is free, and unstable builds are available for both supported operating systems. The project maintains a compatibility list and notes unfinished areas such as AICA filtering, framebuffer handling, exclusion modifier volumes, and renderer features.
For and against
For
- Loads .gdi, .cdi, and .chd disc files.
- Includes four save and four load-state slots.
- Keyboard bindings are customizable.
- Fullscreen and unlimited-speed modes are available.
- Free builds are available for Windows and Linux.
Against
- Requires BIOS and flash dumps.
- Builds are described as unstable.
- Several renderer and emulation areas remain unfinished.
The verdict
Deecy provides core Dreamcast emulation features, but it is explicitly experimental and has unfinished areas. Check its compatibility list and account for the BIOS and flash requirements before setting it up.
Who it suits
Deecy may suit Dreamcast users on Windows or Linux who are comfortable supplying BIOS and flash dumps and using a command-line interface. Its Linux serial option may also interest dcload-serial prototypers.
On the record
- BIOS requirement
- Installation requires copying BIOS and flash dumps named dc_boot.bin and dc_flash.bin into the data folder.senryoku.github.io · read 1 Oct 2026
- Compatibility
- The project maintains a compatibility list and accepts contributions to its dedicated compatibility repository.senryoku.github.io · read 1 Oct 2026
- Controller support
- Deecy should automatically detect, map and use controllers, with manual assignment to guest controller ports available in Settings.raw.githubusercontent.com · read 1 Oct 2026
- Disc formats
- The command line interface can load and execute .gdi, .cdi and .chd disc files.raw.githubusercontent.com · read 1 Oct 2026
- Disc images
- Users select the folder where their Dreamcast disc images are stored.senryoku.github.io · read 1 Oct 2026
- Downloads
- The official site provides unstable builds for Windows and Linux.senryoku.github.io · read 1 Oct 2026
- DreamPicoPort
- DreamPicoPort support is available and can be disabled with the -Ddreampicoport=false build option.raw.githubusercontent.com · read 1 Oct 2026
- DreamPicoPort integration
- DreamPicoPort support is available as an optional build dependency and can be disabled with -Ddreampicoport=false.github.com · read 30 Sep 2026
- fullscreen and speed
- The emulator supports fullscreen toggling and an unlimited emulation-speed mode.github.com · read 30 Sep 2026
- funding
- The official site asks supporters to make a one-time donation through GitHub Sponsors.senryoku.github.io · read 30 Sep 2026
- installation
- Users download and decompress an archive, place BIOS and flash dumps named dc_boot.bin and dc_flash.bin in the data folder, then choose their disc-image directory.senryoku.github.io · read 30 Sep 2026
- Issue intake
- Issue creation is restricted in the Deecy GitHub repository.github.com · read 1 Oct 2026
- Keyboard
- Keyboard bindings can be customized in Settings.raw.githubusercontent.com · read 1 Oct 2026
- Known limitations
- The README lists exclusion volumes and open translucent modifier volumes as missing renderer features.raw.githubusercontent.com · read 1 Oct 2026
- Licensing
- The rest of Deecy is MIT licensed, while included MAME data is BSD-3-Clause licensed.raw.githubusercontent.com · read 1 Oct 2026
- Linux serial feature
- The --scif option pipes the serial port to /tmp/deecy/scif on Linux for use with dcload-serial.raw.githubusercontent.com · read 1 Oct 2026
- Linux serial integration
- The Linux-only --scif option pipes a serial port to /tmp/deecy/scif for dcload-serial prototyping.github.com · read 30 Sep 2026
- Maker
- Sen describes himself as a software developer from France and identifies the project account as Senryoku.github.com · read 1 Oct 2026
