For Sega CD, can this be done, and has it???

[nebrazca78]

Ok, I was thinking about this the other day. Can you put Genesis roms on a CD-R and then play them on your Sega CD? I'm not a programmer (obviously) but it seems like you should be able to write up a little menu system and drop the roms right onto the CD-R. Since the Sega CD needs no mods to run CD-R games, this would be ultra-sweet and extremely beneficial to everyone. The CDX is the most portable console I know of and having every Genesis game on a few CD-Rs to take with you would be exceptional. Seems easy, is it possible? Has it been done already?

[davidbrit2]

Hmm, the Sega CD has 768 KB RAM, I think, so you should theoretically be able to write a converter/loader for small ROMs. I'm not sure if this would involve relocating jumps or changing memory addresses and registers, etc. It might end up being rather complex, but it seems like it should be possible to some extent, theoretically speaking.

And before anybody asks about the Sega classics disc (with Goldenaxe and Columns and some other stuff), it's not just using straight Genesis ROMs. The games have been updated to support multiple loads and whatnot from the CD.

[nebrazca78]

So I guess while possible it's not easy. Is there any way within the Sega CD/Genesis combo's architecture to load the ROM directly into the Genesis' memory? I was thinking along the lines of not even using the Sega CD for anything except its CD drive as a cartridge replacement.

[Darth Sensei]

So I guess while possible it's not easy. Is there any way within the Sega CD/Genesis combo's architecture to load the ROM directly into the Genesis' memory? I was thinking along the lines of not even using the Sega CD for anything except its CD drive as a cartridge replacement.

Alright, I just have to ask. Why?

Why not just get a CDX and be done with it?

[nebrazca78]

Well, I already have a CDX and CD-R copies of almost every Sega CD game. I also have the official CDX carry bag which holds the system, accessories and all the CD-Rs. It makes for a very compact setup for going on vacation and so on. If I were to try and take my 200+ Genesis games with me that would increase the size exponentially and make it unportable. I want to have every Genesis game on CD-R to take with. Sega CD has a lot of great games but most of them are RPGs and/or single player games. The Genesis library is amazing and would make an excellent addition to the setup. Moreover, I think if it is possible to get the Genny roms to work that would also make it possible to do the same with Master System roms. That would be absolute heaven to me. Having what, about 1000 games and a system in a package much smaller than the average backpack? Sweet Mary mother of God, take me there!

[blue lander]

It's basically impossible. The Sega CD BIOS runs out of the memory space where the Genesis game is supposed to fit. And you can't run the program out of the Sega CD's RAM because it isn't directly viewable to the Genesis's CPU (you have to use a BIOS routine to copy small bits of data from the Sega CD to the Genesis). And you can't run the program out of the Genesis's RAM because, well, the game is probably going to want to put stuff there.

Theoretically, I suppose you could create some sort of cartridge that had RAM, but you'd need to bank swap the RAM with the Sega CD BIOS whenever you wanted to grab more data from the CD. And that would probably only work with the simplest of Genesis games.

[nebrazca78]

It's basically impossible. The Sega CD BIOS runs out of the memory space where the Genesis game is supposed to fit. And you can't run the program out of the Sega CD's RAM because it isn't directly viewable to the Genesis's CPU (you have to use a BIOS routine to copy small bits of data from the Sega CD to the Genesis). And you can't run the program out of the Genesis's RAM because, well, the game is probably going to want to put stuff there.

Theoretically, I suppose you could create some sort of cartridge that had RAM, but you'd need to bank swap the RAM with the Sega CD BIOS whenever you wanted to grab more data from the CD. And that would probably only work with the simplest of Genesis games.

Huh, that's a lot more complicated since the Sega CD BIOS takes over the Genesis' memory. What about a Genesis cart with flash memory? I know someone who has one but it didn't have that many games on it. Could one be made that had 1 gig of memory or are you limited to a certain size?

[suppafly]

I would be a millionare if I received one penny everytime someone came up with this idea....I´ve heard it DOZENS of times since 1997 (when I got connected to the internet) LOL

[CrimsonNugget]

http://www.retrodev.com/slo.html
Closest thing to that that has been done so far. This issue has come up before, and loading full ROMs off the Sega CD isn't really possible. There aren't enough resources in the system and I'd assume the programs would get confused if not run from a cartridge.

[Captain Wrong]

Related question: how does the "six pack" CD work? Since that was essentially 6 Genny carts on disc, I've always wondered if it wouldn't be possible to work some magic with that like people did with the SegaGen emulator on the Dreamcast. (I figure this is in the "if it could be done, it would be done" pile, but inquiring minds still want to know how that CD works?)

[Fighter17]

It would be a good idea, but I perfer running the real cartridge than on a CD-R.

[CYRiX]

Well put this into thought:
This was made over 10 years ago, someone had to thought of this and we dont't see one today. So I doubt its possible.

[LocalH]

Related question: how does the "six pack" CD work? Since that was essentially 6 Genny carts on disc, I've always wondered if it wouldn't be possible to work some magic with that like people did with the SegaGen emulator on the Dreamcast. (I figure this is in the "if it could be done, it would be done" pile, but inquiring minds still want to know how that CD works?)
They re-assembled the games from the original source to work within the SegaCD environment. As has been said, the Sega CD just changes the environment too much for all but the most simple ROMs to work.

[nebrazca78]

http://www.retrodev.com/slo.html
Closest thing to that that has been done so far. This issue has come up before, and loading full ROMs off the Sega CD isn't really possible. There aren't enough resources in the system and I'd assume the programs would get confused if not run from a cartridge.

To the layman this page seems to say that you can run a binary from Genesis RAM by pressing start. People are saying there are not enough resources to run most Genesis games since they are almost all 512K or bigger. From what I understand Master System games aren't emuilated by the Genesis, the two are actually compatible. Since the biggest SMS game is 312K (U.S. releases) could you at least run them from a CD-R? The whole SMS library fits easily on one CD-R. Does the Sega CD BIOS take up the entire Genesis RAM? I looked at the Genesis specs and it seems it only has 64K of RAM. How can the Sega CD BIOS fit in there? I must be missing something.

[davidbrit2]

Does the Sega CD BIOS take up the entire Genesis RAM? I looked at the Genesis specs and it seems it only has 64K of RAM. How can the Sega CD BIOS fit in there? I must be missing something.

The BIOS doesn't get loaded into RAM. It's mapped to ROM address space that's directly addressable from the Genesis CPU, similar to what happens when you plug in a game cart. (Right?)

[CosmicMonkey]

There is a similar ap for the PCEngine called Super-Hu Card (http://www.zeograd.com/super_hucard_download.php) that allows you to run the ROMs of smaller HuCard games from a CD.

Read the explanation of how it works on the site. The Mega CD can't do that.

So basically, if you want to play the rather fab Sonic 2 Delta on actual Megadrive hardware, you're gonna need a Tototek flash cart (http://tototek.com/pio/main1/SUBMENU/PARTS/LINKS/OS/mdpro64plus.htm).

[attilathehun]

What the sega cd needs a bleem to play turbo cds and some homebrew programming. LOL That would so kick ass!

[scorch56]

This subject gets brought up regularly in the Sega Xtreme forums.. ad nauseum. So much so that it's in the tagline of the Sega CD forum asking people NOT to ask it because it's already been hashed over and debated to death. The consensus for years has been that it's impossible.