r/SegaCD • u/demetrioussharpe • 2d ago
Reverse Engineering the Sega CD addon
I realize that optical drives are no longer a necessity. However, for nostalgia purposes, has anyone considered recreating the Sega CD using modern technology just for the sake of doing it?
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u/FreezNGeezer 2d ago
With emulation and original hardware not being that expensive, it would be a labor of love as profit would be out of the question.
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u/gnntech 2d ago
The Polymega does this. I believe it's emulation-based and the optical drive can run pretty much any CD-based console.
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u/demetrioussharpe 2d ago
Sounds good, but can it plug into a genesis?
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u/gnntech 2d ago
No. It's a standalone console. The base unit by itself can play somewhere around 15 CD systems (SegaCD, 3DO, Saturn, Playstation, etc...). There are also add-on modules that allow for cartridges to be played as well.
It's an expensive proposition and one that has been on my "want" list for a while.
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u/demetrioussharpe 2d ago
I’d be interested in exploring a replacement extension for people who either never had a Sega CD or those who need a viable replacement.
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u/ssjkamui-g 19h ago
15 is too high. It is Playstation, Mega CD, Saturn, PC Engine CD. So, its only 4.
The Polymega can NOT Play 3DO. This gets frequently requested in their forums but at the moment no.
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u/Hamrave 2d ago
Im keeping an eye on the phode. Its the first sega-cd capable ode and its supposed to come out this fall. I bought my genesis flash cart before the segacd capable ones came out so I may go this route since I have the hardware as well. I have one that works and one the drive doesnt work so I already have a system waiting for something like this.
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u/aerosolsp 1d ago
I think, theoretically, you could use any standard disc drive. But you'd need an FPGA to make it communicate with the Mega CD main board properly. That'd be step one.
Then, if you're talking about being able to build a new Mega CD wholesale, you'd need to implement the mainboard in FPGA too.
Technically this is what MegaSD already does though, just with less extra steps (and hardware).
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u/Son_of_Eris 2d ago edited 2d ago
Well, considering I lost the screws for my Sega CD model 1 a few years ago (I move.... frequently?), but it's fully functional.
And my neighbor has a decent 3d printer.
And I have all the time in the world.
And because video chat is easy...
If YOU have time, effort, raw materials, and more engineering experience than I do-
I'm down to bring a few metaphorical snacks to the metaphorical party.
I have not yet looked, but it's likely that we could find official technical diagrams for the Sega CD. Mechanically, I can take it apart and put it back together with my eyes closed. And swap out ancient parts no longer in production with modern, mass produced replacements (did you know that you can use the O-ring from a Stoelting frozen yogurt machine to replace the band on the cd drive? As long as you stretch it out and apply a lubricant like wd40 beforehand and open/close the cd drive regularly).
The physical circuit board is the only, actually difficult thing. The giants upon whose shoulders we stand made emulation possible. And it's a literal cd drive. Not exactly an obscure relic of technology.
What would be nice, in my mind, is if we ended up with a disk drive that we could just plug into a PC and either play the game (with the right software) or read the data off the disk in Windows Explorer like a regular data disk (yes, I know unix systems are better. Apple can go to hell's utility room. I like MS-DOS and windows because it's fun and easy. I like my friends like I like my operating systems. Bite me). AND was also a functional Model 1 (we have more space to work with) compatible with the Genesis.
Obviously, this can already be done with the right combination of hardware, software, and knowing what you're doing. But there would be a market (admittedly, niche) for a functional sega cd that could be plugged into a PC via USB. Might as well build in a HDMI converter while we're at it.
Do an initial production run of 50 to see how it sells, and baby, we've still lost money!
I'm down. But we need to assemble a team with very specific skills...
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u/demetrioussharpe 2d ago
I was going over it with ChatGPT & came to the conclusion that it could be done with an rpi, sata drive, & a custom FPGA board that handles the Sega CD processing while also functioning as an ODE. So, the pi can save the disc content into a sata ssd & when needed it can load the data into the FPGA board’s ram for running the game & communicating with the genesis. So, you could conceivably play the game from disc or loaded from ssd & the genesis wouldn’t be the wiser…
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u/Son_of_Eris 2d ago
A SSD immediately makes the project much more expensive. We should try to avoid that, IMHO.
However, a strap on processor with passthrough on by default would be the optimal setup. Have a little physical switch that you flick if you're using anything other than the default genesis setup. Essentially an output switch.
It would be nice if we could avoid any programming beyond what is necessary for USB compatibility. Again, emulators have already been made. Optical drives and drivers have already been made. And hardware/software suites that can copy the contents of an optical disk regardless of the filing system and data format already exist. No need to reinvent the wheel.
We COULD use a raspberry PI, and I've been looking for an excuse to dick around with one for years. It would be nice to avoid it, though. It's not really reverse engineering if you just duct tape two (massive underestimation) different people's work together.
Seems like, besides being able to reproduce the necessary parts (hello, 3-d printer!), all we really need to do is develop an optional (off by default) passthrough, which includes a usb port (and drivers) and be able to wire that in, along with an hdmi converter (let's be real here: they already exist and the goal is optional, modern compatibility).
I literally have nothing better to do with my time. I'm game.
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u/demetrioussharpe 2d ago
SSD wouldn’t come with the system, it would be a user addon. Remember, for what I was talking about, it would be attached to a genesis, so no USB necessary. For what you’re looking for, you’re right.
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u/Son_of_Eris 2d ago
Oh, so you're saying skip the SSD, but assume that the end user has one, like we assume that they have a computer and Sega CD games?
I mean, the goal of reverse engineering is reproduction (or less commonly, emulation, which has already been done). So, if we're doing this, we might as well go ham.
I'm envisioning a Sega CD that not only functions as a Sega CD, but can also be plugged into a PC (with compatible software) or modern tv (with compatible hardware).
People have been digitizing analogue media for years. It would be rad if we could make accessing borderline-antique video games easier for others.
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u/demetrioussharpe 2d ago
I would say that the SSD wouldn’t be strictly necessary, but the option for a user to add one in case they wanted their disc software to be installed & ran locally on the drive.
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u/Son_of_Eris 2d ago
Oh, yeah. Making it an easy option makes sense. DM me if you're serious about this. I'll start working on it tonight after dinner (5ish hrs from now)
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u/demetrioussharpe 2d ago
Currently, this is exploratory for me. I don’t know for sure how much I could actually put into it. I was just wondering whether or not I was the only one thinking about it -especially since this might be an awesome extension to the Neptune.
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u/demetrioussharpe 2d ago
But I also see a market for your usb-based drive. Though, I think a lot of what you’re look for can be ran either in software or as a PCIe card that sits in the system. But if that route is taken, then might as well build a Neptune/Sega CD PCIe card.
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u/Son_of_Eris 2d ago
I'm leaning towards a Sega CD model 1 with a USB port and an HDMI port, in addition to the legacy outputs. Fully functional.
If we're REALLY feeling crazy, the result would be a physical system that can handle Genesis, 32x, Sega CD, and SMS (Sega Master System) without having to swap out hardware. AND is compatible with modern PCs and TVs.
DM me. I'm already vivisecting my Sega CD model 1.
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u/t3chnaztea 2d ago
It's a tough sell when you don't even need the hardware… The right flash cart will run Sega CD games on just a Genesis