Updating GDEMU

GDEMU devices are sold fully functional and tested but the firmware (internal operating software) can be updated by placing a special file on the SD card should a need arise.

IMPORTANT: DO NOT reflash your device at the very first sign of trouble. In 99.99% of cases the problem is something you did (or didn’t do) and not a FW bug. You can use GDMENU software to check your current FW version. In general the devices are sold with the lastest one.

IMPORTANT: Devices shipped prior to 2020 and running on FW older than 5.20.0 require a special update to be applied first. Read this blog entry for more details.

The gist of the update process is this:

  1. Flash the updater FW following the usual instructions on the this page (below).
  2. Remove the card and power the Dreamcast once, without any card inserted, to let the updater do its work. Wait for BIOS menu to appear.
  3. Power off and then insert the 5.20+ FW to flash that, again follow the instructions.

For the procedure to work properly you must closely follow these instructions:

  • Extract the firmware file and rename it to “GDEMU.FW”
  • Place the file in the root folder of the SD card
  • Move the write protect tab at the side of the card to “Lock” position
  • Insert the card into GDEMU socket while Dreamcast is powered off
  • Power on the console, status LED will start blinking rapidly
  • Wait until LED blinking pattern changes to 1/2 second on, 1/2 second off
  • Power off Dreamcast, remove the card, unlock the tab
  • Remove the file from the card to avoid accidental update

IMPORTANT: If at any time during firmware update status LED stays completly on or off, or blinks in unexpected pattern, it means an error has occured. Retry the procedure, use a different card if the problem persists.

Latest firmware: 5.20.3



  • Stability improvement #2

5.20.2 (not released)

  • Stability improvement #1


  • Game detection fix for CD-XA media


  • System code update
  • Automatic timing profiles for SoA and RE:CV
  • New INI option to manually cap GDEMU speed


  • Internal changes
  • Newer compiler used

5.14.0 (not released)

  • Internal changes
  • Limited support for long names  (ASCII only) in filenames


  • CCD parser properly detects CD-ROM XA on multisession discs
  • CCD images with scrambled tracks will now work (with small speed penalty)
  • CCD and CDI images with multiple track indexes are no longer rejected
  • Added subchannel scanning for MCN/ISRC data (can be disabled in INI file)


  • NBA Hoopz booting issues resolved


  • Fixed streaming issues on CDDA-heavy games
  • Fixed regression that broke plain ISO images
  • Multi-session MDS/MDF images should now work


  • Audio is no longer slightly muted on some Dreamcasts


  • Fixed CDDA playback broken in 5.8.2 for some games


  • Initial timing fix for Stupid Invaders


  • Fixed button API broken in 5.8.0
  • Option for jumping to selected image on system reset


  • Image limit raised to 9999, folder prescan removed
  • Initial support for high speed mode on SDV2 / SDHC cards


  • Fixed erratic behaviour of the button API on some units


  • Option to disable strict image integrity tests via INI file to allow oversized media for undub / translation projects
  • Image limit raised to 64
  • Initial support for up/down button emulation via API


  • Some fixes for Bleem – beta now boots and works
  • BIN image support for PSX games (single track only, raw sector format)
  • CDDA pause/continue issues resolved
  • Lid open and disc detect time can now be specified in INI file


  • Initial revision for v5 models

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