GD-CD Rom Swap?

SLiDE · Post by **SLiDE** » Mon May 03, 2004 5:07 am

Does anyone know if anyone else has tried to swap a CD-rom drive for the GD-Rom drive in a DC? I just figured if it's all just reading information it shouldn't matter as long as it was fast enough to handle it--that way I could have one DC that was able to handle all of my EMU's and one for my original DC games without burning out the GD rom drive.

If it can be done then what's to say a HD couldn't be substituted for the GD also? The are just devices to read information aren't they? It would aid in the development in Homebrews as well...anyway, just a thought.

az_bont · Post by **az_bont** » Mon May 03, 2004 6:17 am

From what others have said, not only is it possible, but it will also be able to read GD-ROMs too.

A hard drive was created for the Dreamcast by Cryptic Allusions (I think), but it couldn't simply replace the GD-ROM. It could be accessed by homebrew titles specifically programmed tor read from it.

Rand Linden · Post by **Rand Linden** » Mon May 03, 2004 10:41 am

NOT possible.

Rand.

natiels · Post by **natiels** » Mon May 03, 2004 11:45 am

Its definitely not possible to simply swap one out for the other. You could theoretically hook a microcontroller of some sort up to the gd-rom port and have it translate the data requests and then send them on to a normal cd-rom. I am guessing the DC uses ATAPI commands to talk to the gd-rom based on the fact that there is a gd-rom controller board that actually uses an OTI-9220 ATAPI cd-rom controller chip. If you did that you still would not be anywhere near reading gd-roms, but it would be kinda cool.

You could probably also hook up a hard drive using a similiar method. Hard drives use a different command set for accessing the data so your command translation would be more difficult. It might sound simple in the way i am saying it but it would really require creating a whole controller board that sits between the DC gd-rom port and your device cd-rom or HD. Also it would require tons of research and reverse engineering on the gd-rom port to see exactly what it is doing when it sends a request for data.

I am actually attempting something like this but i am not an EE so i am learning everything right now. I havent gotten much beyond doing research and thinking about some ideas. If i ever do accomplish anything it will be months and months in the future.

MaskdDingo · Post by **MaskdDingo** » Sat May 15, 2004 1:47 pm

I am also very interested in what it would take to be able to do this. I have a DC here with a completely burnt out gdrom, but it boots just fine when i remove the entire gdrom unit. It would be really cool if one could build a controller that could then fit inside the case along with a laptop HD. instant mini computer. Which brings up another question.. If a HD can be hooked up in this manner, would it also be possible to "teach" the DC to write back to the disk? That would be really nice... I'm thinking DC linux... that would rock for Development! Compile and test right on the DC? LOL! I think natiels assesment is acruate... Theroreticaly it should be possible... but it's probably very very complicated.

natiels · Post by **natiels** » Mon May 17, 2004 10:39 am

Right now i am attempting to figure out a way to hook up logic analyzer probes to the gd-rom connector so i can see what is going on over the connector while a game is loading. If anyone has any ideas for this I am open to them or if anyone knows where to get a connector that is compatible with the gd-rom connector. I found a molex slimstack connector that is almost identical to the gd-rom one but you have to buy them in lots of 3000. I also found another company that i ordered some samples from. The samples should be in by the end of the month.

It really would be an awesome tool for development. It would be very easy to put a usb 2.0 chip on the board and have really fast access to the hard drive. no more slow coders cable.

Hopefully things work out and I can keep progressing with this.

Rand Linden · Post by **Rand Linden** » Mon May 17, 2004 11:24 am

Don't waste your time -- unless you've got lots of it, and nothing else better to do.

Rand.

natiels · Post by **natiels** » Mon May 17, 2004 12:34 pm

The truth of the matter is, Rand, that everyone on this board probably has something better to do with their time then play around with a dreamcast. Playing your dreamcast or modding it isnt likely to make you money, it isnt going to make you a better person and it will probably not get you ahead in life in any way, but those are not the reasons we are all at this board. We are here because we think the dreamcast is a great little machine and we have FUN using/wasting our time playing with it.

Personally I think its a waste of time to read over posts to simply say "NOT possible" and then to use more time to follow up two weeks later and post another discouraging comment. As I stated above tho, maybe your not doing it because you think its the best use of time but rather because you enjoy it and if thats the case then who am I to tell you its a waste of your time.

Zexmaix · Post by **Zexmaix** » Mon May 17, 2004 1:43 pm

Yeah, I as well would LOVE to see if a external or some type of HDD would be capable of working for the Dreamcast. I know there has been a HDD rigged to work with the Dreamcast, but I last saw pictures of it about 2 years ago. It was crude, but had a regular HDD hooked up to it with the ribbon coming out of the Dreamcast and the works.

I have the same thoughts as MaskdDingo, DC Linux. Make the Dreamcast into a powerful little half-computer. Much like X-Box Linux. Possibly keeping the Dreamcast still in tact to switch from OS to DC Games without a hitch, by use of a simple 3rd party program saved on the HDD. Just thoughts of mine.

Pyrosurfer · Post by **Pyrosurfer** » Mon May 17, 2004 2:46 pm

You can swap the gdrom laser with a cdrom laser if they are pin compatible. If you want a fast hdd interface the best thing to do would be to somehow connect it to the 8 bit in of the proprietary sega modem chip, and use a hacked modem driver.

Rand Linden · Post by **Rand Linden** » Mon May 17, 2004 6:18 pm

natiels,

There's a big difference between "playing around with a DC" and "I'm going to swap a GDROM with a CDROM and add a HDD controller at the same time."

My advice is free -- use it, discard it, ignore it as you see fit. It's not a discouragement against what you want to do -- rather, it's an opinion based on years of experience and hands-on empirical evidence.

In the meantime, I anxiously await your "very easily added USB 2.0" enhancement for the DC.

Rand.

natiels · Post by **natiels** » Mon May 17, 2004 11:28 pm

i guess i took your post too harshly, Rand.

I said it would be easy to add usb 2.0 to the board that connects to the HD. So if I can ever hook the HD to the dreamcast having usb 2.0 connected to the HD would be very doable. I have no doubt in my mind that actually getting the DC to HD going will be very difficult.

If you want a fast hdd interface the best thing to do would be to somehow connect it to the 8 bit in of the proprietary sega modem chip, and use a hacked modem driver.

I thought about somehow trying to use the expansion bus, but i wanted to be able to play games with full use of the modem(one of my fav games is PSO). I basically want to use the microcontroller as a middleman between the hard drive and the dreamcast that translates the gd-rom calls into HD commands and then sends the data back to the DC. That way you don't have to have specially written software. All the homebrew that runs on DC now would run off the HD. It's a million miles away right now though. Hopefully it is something that can happen. I think it would be really great for the community.

SLiDE · Post by **SLiDE** » Mon May 17, 2004 11:51 pm

I am close...I have had some extra time this past couple of weeks and I called my friends over at AGI Design Studios...they work with arcade prototypes and they happened to have a naomi just sitting around. that's not what helped us, rather the documentation on the I/Os that were with the prototype unit did. We get it to read with the CD rom but we have some compatability issues...I am going to try a few other things when I have some time next week--I am not a programer or a hardware guy but I know enough to go to the real experts. Let me just say this...these guys are seriously nuts! all you have to do is walk in and say something can't be done and they get this gleam in their eye. The reason I know them is I have done some graphics for their redemption prototype games and favors fly back and forth. I am really excited because they think they can get everything on a small board to fit inside but first they want to know it works flawlessly. If this works I might try and get a kit together for anyone who wants it.---anyway, just an update for you guys.

Prophet][ · Post by **Prophet][** » Mon May 17, 2004 11:55 pm

Midnight Obsession a few years back swapped the laser in the gd-rom with one from a portable cd-player. Worked fine, I think he has how he did it somewhere buried in these forums.

Alexvrb · Post by **Alexvrb** » Tue May 18, 2004 12:44 am

Prophet wrote:Midnight Obsession a few years back swapped the laser in the gd-rom with one from a portable cd-player. Worked fine, I think he has how he did it somewhere buried in these forums.

Swapped the laser, or swapped the lens?

Post by **Quzar** » Tue May 18, 2004 1:39 am

Ive always fancied the idea of a rom chip that would sit in place of the CD rom and would hold the dc-load utility so that it loads faster and dosnt break the GDrom for just devving. oh well =P....

Prophet][ · Post by **Prophet][** » Tue May 18, 2004 7:42 am

Alexvrb wrote:[quote="Prophet]Midnight Obsession a few years back swapped the laser in the gd-rom with one from a portable cd-player. Worked fine, I think he has how he did it somewhere buried in these forums.

Swapped the laser, or swapped the lens?[/quote]

I'm pretty sure it was the laser, I can't seem to find the topic but I'll search a bit more, it was quite some time ago. Back when hardware mods were big.

natiels · Post by **natiels** » Tue May 18, 2004 8:30 am

rather the documentation on the I/Os that were with the prototype unit did

Is it in PDF format?? would you be able to get a hold of it?

That is interesting news about hooking a cd-rom up to it. That may mean that it is pretty close to standard ATAPI with maybe a few custom commands that are causing your incompatability issues.

Prophet][ · Post by **Prophet][** » Tue May 18, 2004 8:34 am

I suggest you do a forum search on the gd-rom, you might find some interesting information, especially bout people trying too hook up cd-roms

natiels · Post by **natiels** » Tue May 18, 2004 10:06 am

Believe me, I have searched many forums for all the info i can get on the gd-rom. The best thing as far as technical info i have found yet is the partial pinout of the gd-rom connector that bitmaster did. There is also a simplified OTI-9220 overview on some other site. The OTI-9220 is a cd-rom controller chip used on some version of the gd-rom controller board. An actual datasheet would be much better. In the end though i think i am going to have to just do the research myself, which is why i am working to get a logic analyzer hooked up to the gd-rom port.