Imbrium, contd.

UPDATE2: There’s a bug in early GDEMU bootloaders that was fixed in late 2016, it can randomly lock up the device while trying to execute the updater. Sorry about the download link confusion, I have a revised version ready but I need to test it some more. I will upload that one in 2-3 days.

UPDATE: The updater was tested on pretty much every GDEMU revision there was, including the early 2014 v5.0 models, and worked every time so I’m releasing it.

Okay – the updater for older GDEMUs is ready and has been tested. Still, after that angry comment in the last post I’m again questioning the wisdom of openly distributing a FW file that can potentially brick your device if you don’t follow my instructions to the letter. And apparently some people only read every second line or so, and then come to their own conclusions.

And, frankly, there could still be a bug in it, or perhaps my instructions are not that clear to begin with. Though – somewhat surprisingly – the people who have most problems are those that nearly don’t speak English and use various automated translation tools but also the native speakers.

My English might be somewhat rough around the edges but when I ask you to first rename a file and then copy it to the card, it’s not because I’m unable to form a complex sentence. You are supposed to do exactly that, in this particular order, step by step. I meant it when I said pretty much all issues people had updating the FW were self-inflicted.

So, this being a big update and a potential major disaster waiting to happen, I’m asking for some volunteers first. Leave a note in the comments, especially if you own an older (pre 2016) device. I will select a few people and offer full help should something go wrong. If that goes well, I will upload the updater for everyone to use. Also, people who can make a YT tutorial for those with, shall we say, shorter attention span are very welcome. A good video might be useful as well.

The gist of the update process is this:

  1. Flash the updater FW following the usual instructions on the blog page.
  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.

And that’s it. Few notes:

  • Older GDEMUs (and I mean the realy early ones) have different flash patterns for FW update. In general it’s OK to go to step 2 anyway because if the file was corrupted or something went wrong, your device will simply blink and not start, but will not be bricked. So you can retry.
  • When booting the updater, wait for the Dreamcast to go the main menu. Then you can turn it off. If you get weird blinks on your device instead, contact me. The short LED blinking burst on power-on is normal.
  • Speaking of weird LED flashes, make sure your Dreamcast runs well and did not just get affected by the “bad PSU contact disease”. For example run it for few minutes first and make sure it doesn’t randomly reboot or go back to the menu from inside a game. You really don’t want the power loss to occur when updater is running.
  • If you turn off the console after updater has run and then turn it on again, GDEMU will blink like if it had no FW installed. That’s normal, it now wants the 5.20+ version and will no longer work with any previous one. Though if you follow the instructions you shouldn’t ever get here.
  • The updater actually does have some rudimentary OLED support but the 5.20 FW does not. I really need to make that connection diagram ASAP in case someone wants to use it.


I’ve prepared 5.20.0 FW for GDEMU, this one has fix for Skies of Arcadia and Resident Evil: Code Veronica. It’s been tested but there’s a lot of small changes to the code base so some new bugs might be present.

There’s a catch though. This FW is only compatible with GDEMUs that have the new improved bootloader installed. How can you tell if you have it? If your GDEMU was shipped in 2020 then it is compatible, anything earlier is not. For the earlier devices I will prepare an upgrade FW to be installed first, but this is not yet finished. It won’t be too long but it needs a lot of testing and that takes time.

DO NOT attempt to flash this FW on an older GDEMU.

The fix for SoA and RE:CV requires GDEMU to be slowed down – because these are actually game code bugs that are triggered by loading data too fast. I didn’t want this to affect other games as well (since there’s no need) so there’s auto-detection code added. But in case that doesn’t work, or if you want to slow things down manually, there’s a new INI option:

read_limit = N

Where N is a value between 600 and 1250 (kB/s), or 0 to disable the limiter. The default is -1 which means “automatic”.

Now, the exact speed I’ve picked for automatic setting might still need some tweaking, especially for RE:CV and/or 60Hz regions. So report back any issues.

I will move the FW download link to the correct page once the upgrader is ready – for now you can get the file here.

Foregone Destruction

I should be able to wrap most (if not all) Phoebe orders to UK and South Korea this week, or early next. Some COVID-19 related safety procedures are still in effect and that limits the scale of our operations, everything takes more time.

In the meantime I have prepared a batch of Rheas that you’ll be able to order this Saturday at 12:00 CEST. Now, this being smaller batch than usual and with more people sitting at home bored, I would assume it’s going to sell out pretty fast. Sorry in advance but that’s the situation right now.

Keep in mind there are still quite a few countries that I can’t ship to – most notably Australia, China, Ireland, Japan, New Zealand and Spain. See the updated full list in the last post. I will not accept orders from countries that I can’t ship to. And yes, I know it’s weird that I can ship to Portugal but not Spain, or to UK but not Ireland. But I don’t decide these things, this is related to various border crossing restrictions and international flights still being on hold.

One more thing, since it’s going so slow I figured maybe I should release the GDEMU FW in parts, first the fixes for SoA and RE:CV (since that’s pretty much done), and the OLED stuff later. A lot of people have been asking for those fixes lately and perhaps they don’t much care for the other changes. So I’m going to try and come up with something in the next two weeks.

UPDATE: Rhea orders are open now closed. Well, that wasn’t as bad as I’ve feared, there was plenty of time to grab one.