DreamDash BIOS

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

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