More prototypes

Meet GDEMU 5.1:

GDEMU v5.1
This is a revised PCB that I’ve been thinking about for quite some time now. In the end I chose the smaller variant with felt pads for initial production as I’ve had that already well tested. But the issues I had lately with sourcing pads that would stack to correct height got me to rethink the whole idea and hence I dug up the other design and actually had it made. As you can see, it works:

GDEMU v5.1 - inside DC

That’s the good news, the bad is it’ll take another week to get the revised PCBs manufactured, so again a small delay. The new variant will be called 5.2, and there are just a few 5.1 units in existence. Those are identical except the location of the optional support near the button, it has been moved a bit. You can use it or not, it’s up to you, it might prevent proper seating of the connector so that’s why it’s optional. Might not fit perfectly into each Dreamcast.

The left support (and the screw pretty much as well) are mandatory if you want GDEMU to be stable. These are however far enough from the connector not to cause any issues. The screw is metric though, can’t get anything else in this part of the world, and apparently the original one was not. So it might be a bit difficult to install it at first, just be patient with it and don’t rush. Also, do not attempt to put the screw in alone, you will reach the console mainboard if it goes deep enough, and then it’ll cause damage to it. To make sure noone attempts that I will be adding a small piece of paper to each sent GDEMU with this particualar warning printed.

Other than longer PCB to allow for the screw there are no functional differences between this and the v5.0 model. Or the original v4 that used the remote for LEDs and buttons. Oh, and about that, I will have a few spare PCBs that were meant to be remotes but were never used. I can give those away to people who would like to assemble one on their own. Just the small PCB though, no components or wires. Ask me about it when I contact you for payment and I will add one PCB to the envelope. Offer valid only as long supplies last🙂

40 thoughts on “More prototypes

    • Well, you can’t for now, but in 3-4 weeks I will be done with sending the preordered units and by then I should know if there will be another production run.
      I’m sorry but you have to be patient for now. Please visit this blog to keep up to date.

      • 4* 1206 LED, 4* 0603 330ohm resistor, 2* TACT SPST-NO button. You can put only LEDs or only buttons on it, or both.
        Use the mail address you got with preorder confirmation to contact me.

        EDIT: Oh wait, do you mean the bare PCB for GDEMU? That won’t help you at all without the program for MCU and FPGA. It’d be dead without it. And for obvious reasons I’m not releasing that code to public.

      • Sorry, yes I meant programmed MCU’s and bare PCB, and I’d add the rest of components my self, of course I don’t know in which stage you program your units. So my idea might be stupid.

  1. Ah, OK, no matter, I misunderstood. I tought it was the GDEMU main PCB not the extension one.Sadly I’m not one of these lucyy person.Anyeay I’m always interested in buying one.

  2. Great stuff, always happy to see updates on this!

    I missed pre orders but am keen to order one when they next become avalible.

  3. Selling bare PCB and programmed MCU is rather difficult as the MCU needs to be soldered down to get both power delivery and easy access to JTAG pins. I’d have to make a special PCB and adapter just to be able to do that outside the system. That kind of defeats the low cost idea, sorry🙂
    Also, trust me, soldering down two TQFP-144 packages is not that easy. Sure, people can do it, but if there is even a single pin shorted or not soldered right you will get a massive headache trying to debug your unit. It’s much easier if I test since I know what to expect. You pay for all that, so you don’t have to worry about it.

  4. I do soldering even more difficult than this just with an hot air station and a soldering iron and I never made a mistake (sometime I use also a microscope).I repair arcade PCBs since many years and I’ve encoutered a lot of ASIC in QFP package with very fine pitch (200+ pins).

  5. I want the new model if it’s possible! New pre-order list? All soldered. Only plug and play it’s my idea. I’m sorry but i don’t know if I’ve undertood right.
    I’ll be w8ing for new units!

  6. The extended pcb is a great idea for stability, much better design imho. My question is how possible would it be to have a sd connector that is turned around facing the controller ports and angled at about 45 degrees to make it simple to remove the card without any hassles of removing the shell? Or is there a way to re-locate the sd card elsewhere? Just curious, lmk.

    • Eh, turned around and angled?
      Right now you can insert/remove the card by just opening the lid. The hole left by GD-ROM extends all the way to the back so it’s doable. If the connector was facing any other direction it’d be pretty much impossible without removing the cover completly.

      Also, the GDEMU is expensive as it is. Will you pay more for a much more complicated PCB design, that will require a test run as well to make sure it even works?

      I don’t recommend it in general but if you really don’t like the position of the card socket then use an extension cable. Just make sure it’s short.

      • Just looking at some videos of the product it looks like it’d be a tight fit depending on the size of your fingers/hand to remove the sd card as is in it’s current state. With the addition of the extended board with the screw for security it should be easier however to remove the card without worry of damaging any connectors without removing the top lid of the DC. I do like the idea of the extension cable just in case I have any issues personally. Thank you for the suggestion.

        At this point I think you have a solid working product and any future updated boards will simply be for convenience, which I don’t mind paying for personally. Depends on how convenient it becomes.

        I’m looking forward to having one of your new units when they’re available.

        Thanks for the reply!

  7. Hi,
    would it be possible on future PCB to have SD slot on a different PCB so as to fit it on Dreamcast’s shell ? I’d like to change SD card without opening upper cover.

    Thanks for the reply!

    • Not really, that would make everything more difficult to install. Not everybody wants to cut a hole in the shell, in fact most people prefer not to.

      As I’ve said, I don’t recommend it, but you can try to use extension cord. It should work as long as it’s short.

  8. 5.1 vs 5.2 is that the 5.1 have the left support removable and 5.2 not? also any news on menu selection?

    • No, both are identical except the location of the hole next to the button. I added it last minute to 5.1 and missed the mark by a few mm.
      I’ve started coding the menu but I don’t want to use KOS as I’m unsure about commercial usage, so it’s going to take some time.

      • I don’t think it would actually matter as long as you weren’t selling the menu software itself. Most of the code in KOS is licensed under a BSD variant, which is fully compatible with commercial closed source software. The only problem would be that some of the utilities KOS is packaged are licensed under the GPL, which would require you to distribute your source. But, as long as you avoid using those, using KOS for your menu should be completely fine.

  9. Hi,

    I was is there a sd card size limit that we must be aware of when using this product? Could we for instance use a 128gb sd card?

  10. I must say, I like the idea of the screw mount. I’ve only removed/replaced the SD card once since installing the gdemu v5.0, but it really didn’t feel very safe – the extra security of the screw mount would be very welcome.

  11. For anyone who wants to build their own images be aware that GDEMU has limitation of about 2GB per image. Tried 1,99GB and it didn’t worked, tried 1,85GB and it worked.
    Deunan, is it possible to disable this limit (up to 4GB) in future firmware updates?
    BTW can’t wait for the GUI🙂

    • GDEMU emulates an optical drive, even if I did remove some sanity checks you’d be still limited to 256min long track, which is about 2250MB. And possibly even that would completly confuse BIOS and other programs that don’t expect discs that big.
      That’s not mentioning having to re-check if I handle >2GB offsets everywhere correctly. A lot of work for minimal gain. Won’t happen, sorry.

  12. I just read the last news, it’s great you are interested also in other old systems.In my opinion of ancient retrocomputing collector, two are the systems which deserve attention: FM-TOWNS (PC and Marty Console) and Sega Saturn.For the first there are no available schematics and documentations (it should use a serial interface based on a Hitachi MCU) but if you want I can donate you one of my machine with faulty CD-ROM unit and share all the info I have.For the latter, someone has already studied the CD interface, you can find all the project here:

    Feel free to ask me other info.

  13. I agree that an EMU for the Saturn would be fantastic. There is supposedly one being made by a Chinese team by it’s supposed to utilize the cartridge port.

  14. 2 Questions…

    What image formats are supported?

    Also it was my understanding GDI images are the most accurate rips you can get so I began backing up my games to GDIs with the SD card adaptor through the serial port. However, the ripping program I use gives me the option of ripping the GDI’s tracks as either .BIN files or .ISO files. I know .BIN is just a raw binary rip of the track and that .ISO is meant to preserve the file system found on most DVDs, but my question is how do these relate to Dreamcast games? I generally use .ISO for DVDs and .BIN for music CDs, Sega CD games and Sega Saturn games, but which of these two options is best for the tracks of a GDI? Do the tracks even utilize a file system which the .ISO format can work with?

    • In this case BIN stands for 2532 bytes long sectors (aka raw), and ISO for 2048. You only need to get 2048 for DC games to work, which is all the user data – the rest is a header and checksums. But most rips are raw and GDEMU works with that without any noticable slowdowns. In the end it’s for your personal use and up to your preference.

      • Thank you for the info. Also I got to thinking and I was wondering g if maybe you have any plans on building a version that can read from a hard drive instead of an SD card in the future? It seems like there is plenty of space in there for one and even the 128 gig SD cards that are starting to hit the market can only hold about half the system’s library so I was curious. Then again I suppose the extra bulk of the HD would require a more costly method of mounting it in place.

        Also how would one go about swapping discs with the GDEMU, does it support music disc images for the CD player built into the system bios, and will it be able to work with homebrew applications?

        Also I know this is a bit off subject, but I have not found any info on it and I rarely get to ask questions of anyone who knows as much as you do about the system. Would you happen to know where it is that the Dreamcast stores the Phantasy Star Online key code information and whether or not this information can be erased to allow a different key code to be entered? I have come across a few systems I couldn’t use my saves on because they already had a code on them.

  15. Oh and I almost forgot…

    Thank you for your work on this project. I hope to be popping one of these into my Dreamcast soon.

  16. There are no plans for making GDEMU anything more than it already is. I’ve already explained why several times and will not do it again.

    You swap discs by switching the image with the button. Hence the button is actually important feature, the menu will be just a nice bonus.

    Of course it supports CD audio, it works with the DC built-in player, and homebrew as well.

    Various settings, including for example your selected language and GD auto-booting flag, are stored in the internal FLASH. There is a homebrew app out there that can erase all of it but I didn’t test it myself. Might not work or have nasty side effects.

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