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DreamDash BIOS

DreamDash is a replacement BIOS for Dreamcast power users and developers. It requires KallistiOS to build.

dreamdash-preview

Functionality

  • Launch binaries directly from SD card or IDE drive
  • dcload-ip and dcload-serial binaries embedded directly into ROM
  • Menu entries appear for DreamShell or RetroDream if found on SD or IDE device
  • Configurable to auto-boot into DreamShell or RetroDream if found on on SD or IDE device
  • Launch games or applications from GD-ROM drive
  • Choose between light or dark wallpaper theme
  • Choose between retail or devkit style intro
  • Support for Dreamcast consoles with 32MB RAM
  • Build as a BIOS, a standalone binary utility, or a CD image

Issues/Limitations

  • BIOS image will not work if stripped binary size is larger than roughly 500KB
    • Build your KallistiOS, kos-ports, and DreamDash with -Os and -flto=auto to help stay below this limit
    • Always have a backup BIOS image on your console for recovery if flashing to console
  • Certain older homebrew is not compatible with consoles using a custom BIOS without patching
    • This applies equally for launching from CD, SD, or IDE
  • Phantasy Star Online Ver 2's anti-cheat tamper protection causes bugs when launched via this BIOS

How to Use

  • Set up KallistiOS on your computer.
  • Compile KOS and the zlib/libpng kos-ports with -Os and -flto=auto in your KOS_CFLAGS to keep code size small.
    • KOS master with commit ID 4346a85 is known to work properly.
  • Open a terminal and source your KOS environment, clone this repo, and change into this repo's directory.
  • Run make to build dreamdash.elf. Run kos-strip dreamdash.elf and check the filesize. If larger than 500KB, it may not work and can produce a non-working BIOS image, so check your KOS_CFLAGS and try again.
  • Run make all to build everything. Check the release directory for generated files:
    • dreamdash.bin: Plain raw binary
    • 1ST_READ.BIN: Scrambled binary for booting from CD-R
    • dreamdash.cdi: DiscJuggler CDI image for burning to CD-R (requires mkdcdisc installed to $PATH to generate CDI)
    • dreamdash.bios: BIOS image with standard bootup intro. There are several variants:
      • BIOS files with devkit use the devkit bootup intro
      • BIOS files with nogdrom are used on consoles with no GD-ROM drive installed (currently untested!)
      • BIOS files with 32mb are used on consoles with 32MB RAM modification
  • Use DreamShell's BIOS Flasher application to write the .bios file to a Dreamcast's writeable BIOS flashROM.

Acknowledgements

  • KallistiOS and DreamShell - kernel and drivers for the underlying operating system
  • Cpajuste - Dreamboot, from which this project was originally forked
  • Troy D. Hanson & Arthur O'Dwyer - ut* C structures libraries