Dreamcast:BIOS Replacement Mod

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Revision as of 17:53, 27 February 2024 by Derf (talk | contribs)
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If you want region-free game loading, to load burned game backups on a model VA2 Dreamcast, to force all games to boot with VGA output, or your BIOS chip is simply corrupt; you can replace the Dreamcast BIOS chip with a new one.

Installation

A video detailing this process can be found on ModzvilleUSA's YouTube channel.

  1. Disassemble the Dreamcast and locate the BIOS chip IC501 (labelled MPR-21931-X1, MPR-21933-X1, or MPR-21931-X2).
  2. Turn the Dreamcast on and use a multimeter to measure pin 23.
    • If it measures around 3.3V, you will need a 3.3V BIOS chip.
    • If it measures around 5V, you will need a 5V BIOS chip.
  3. Remove the existing BIOS chip. You may find the Replacing ICs page helpful.
    Dreamcast BIOS Replacement Removed.jpg
  4. Solder in the new BIOS chip.
    Dreamcast BIOS Replacement Replaced.jpg
  5. Solder a wire from pin 1 of the new BIOS to pin 23.
  6. To write-enable the BIOS (to be able to update the BIOS via software in the future), solder a wire from pin 44 on the new BIOS to pin B14 of the GD-ROM connector. There are alternate locations for a cleaner install, but are generally more difficult to solder to.
    GD-ROM pin B14
    Alternate pin
  7. Plug in the fan and GD-ROM (or GD-EMU) and test to make sure that it boots. Ensure that you prop up the GD-ROM or GD-EMU so that it is flat and level, as it will otherwise not make a proper connection.