ToToTEK.COM

[MottZilla]

This is an idea I had that perhaps would be a cheaper solution than the Flash Cartridge currently available.

Basically, You'd want a Genesis Cartridge with a good amount of RAM, 32Mbits atleast. Next, you'd build a ISO and burn it for your Sega CD. The CD you burn would have a simple program on it to load a ROM file from the CD to the RAM Cartridge and then execute the game.

One thing that would be nice is you could keep a collection of virtually every game you wish to play on a CD-R and load them without the need of a PC to program flashrom. And you could perhaps use the imbedded Save RAM of the Sega CD to save your games onto when you want to play a different ROM with SRAM.

Do you think it'd be fairly cheap to make a cartridge like this? Also, for something similar, there is a program "SLO" available with source code. However it seems to load a binary that is designed to run from RAM off CD. But with some modification, I think this would be a good alternative to the Flash option.

I've had this idea for awhile. I always thought it would be cool to be able to load ROMs off of the Sega CD. And it'd be perfect if it were 32X compatible and as large as the largest game available (40Mbits?).

Any feedback would be great.

[rbudrick]

I think I saw this topic come up once in another forum, but I think the answer was that it couldn't be done due to some hardware limitation or something. Then again, maybe they weren't adding a ram cartridge into the equation. Maybe it was the cherryroms forum...can't remember.

Would be very cool, however. Neat idea. Cool idea for the Turbo Duo too. Some may even say Jaguar, but I won't go that far.

-Rob

[MottZilla]

Well it can't be done with JUST the Sega CD as it doesn't have enough RAM, and its not really at the memory mapped point it's supposed to be at.

The some insight from a friend, I think this is actually very possible to do. Backup/Copier Devices produced for SNES and Genesis would load DRAM chips with the ROM from a floppy disk. What would be different here is that we already have a massive storage medium (CD-ROM) so we only need a cartridge with the DRAM inside.

The 2 key points of this idea over a flash cart though are:
A. Cheaper Cost Most Likely.
B. You can store a huge collection of games on a CD-ROM, and never need a computer to program a cartridge.

And another thought about games with SRAM. There's a program out there that can dump Genesis Cartridges via a Parallel Port to Genesis Controller 2 cable. This could probably be modified to instead Send or Recieve the SRAM from your cartridge. That combined with being able to store games on the Sega CD's built in SRAM would probably make it fairly comfortable.

[Guest]

I'm not sure but you may not be able to switch off the Sega CD BIOS via software. This is a necessity to start a game from the cartridge port, if the Sega CD is on, the BIOS is on the cartridge (ROM) bus. On power-on, a specific pin or two determines whether or not you have a game cartridge or "nothing" (Original Sega BRAM card counts as nothing) inserted. If nothing is inserted, only then is the Sega CD started. Maybe this cartridge pin can be toggled anytime to disable the BIOS, I don't know.
Something to look into would be the Datel CDX cartridges and their onboard hardware, they manage to at least jump from cartridge ROM to BIOS ROM, which we know is possible through those pins. Maybe the same principle can be applied to jump back. In that case the RAM cart could decode a BIOS/game select register.

Some things I should point out:

-the way copiers handle BRAM would require the full 256kbit of BRAM in the Sega CD, not that it matters because there's no way to get a game to save to that RAM without more hacks.

-writing the RAM cart will be tedious, the Sega CD may need the BIOS to even access the CD.

I really don't see the appeal in loading ROMs off the Sega CD, I'd much rather have a "RAM cart" with a compact flash interface or something, it wouldn't likely be any harder and you could load a game instantly, backup games and actually save BRAM to the flash memory heh

[kyuusaku]

That was me

[MottZilla]

Well, the Sega 32X can be used in conjuction with the Sega CD, so I'm sure there are ways to access the cartridge port. Esspecially since the Sega CD can use that BRAM cartridge.

I agree with you that a simple Genesis cartridge with a CF or SD memory card interface to load ROMs and load/save SRAM would be awesome. And hopefully, a bit cheaper than the current 64mbit flash cartridge. The reason the Sega CD thing came to mind was that it seemed alittle more possible for me to do than building my own full backup unit for the Genesis.

Obviously, that's what I'm looking for. But unfortunately unlike SNES I rarely see fair deals on backup units for Genesis, or N64 as well. I don't like the idea of paying hundreds for some device that isn't perfect, and costs more than it would for me to buy all the games I wanted to play.

If you have any ideas what I might be able to do that would be great. I've thought about cannibalizing 2 of these 16mbit sport games I got for 1 cent and putting in EPROM sockets. They even seem to have SRAM chips. It reminds me how I still need to solder Star Fox 2 to my Doom cartridge someday.

I think you mentioned the MGD2 before on another site and that you had one. I was curious how exactly that works. It seems to have RAM cards that you can use I guess with any of the systems it plays? I never quite understood though how all that worked. I've seen one for sale but it cost quite a bit and was in europe.

One last thing, I assume that the Tototek is the only device for 32X play? Or would the MGD2 work for that.

[Suppafly]

Short answer: IT CANT BE DONE without reprogramming the games

Long answer: google it up!

[Guest]

Trust me, it won't be any easier for you to build this Sega CD thing than it would be to build your own backup unit.

Trust me again, MD-Pro IS a deal. Theres that thing called supply and demand, not everyone is a bargain shopper. If you want a Gen/N64 unit, you'll have to get lucky, pay the $100+ or pay even more to build one yourself, simple as that.

The Sega CD doesn't "access" the cartridge port, the Sega CD's BIOS sits on it, what the additional CPU does I don't know. The external RAM cartridge as I said "counts as nothing", unlike a ROM cart (game), it's made to be used in conjunction with the Sega CD and is safely decoded to a non-conflicting memory area, the cartridge and Sega CD are working together in that situation. 32X is a completely different story, IIRC it sits itself in an entire area for expansion away from the 32M allocated for cartridge ROM.

MGD2 works like what it is, an embedded microcontroller system. There are really expensive "shells" that you deposit a DRAM or SRAM memory card into and then serially program them via parallel port or MGD2 main unit. Once programmed, the shells retain their contents and act as a cartridge. The MGD2 is not a very flexible unit , it's from 1992 and acts like it, it's very picky and requires a lot of background knowledge. It has the highest learning curve of any 16-bit copier hands down. For you to get a MGD2 set with MD shell and 32M (the largest) card, I think the minimum you can get that for is $200. But yes you should be able to run 32X from a MGD2 shell.

MD-Pro is the cheapest and by far the most obtainable MD unit available and should you require the features of other units, just bite the bullet and buy another. If you need to backup games, there are plans available on the internet for simple projects.

[MottZilla]

Sounds like I'm better off with EPROMs, though I don't know how much they'd cost these days... Not quite as convient though. I did find some sources for very nicely layed out cartridges that may be easy to install sockets into. Ofcourse some games it would be cheaper to get the originals used somewhere.

Still I think a nice compact cartridge design to load ROMs from CF or SD card into RAM would be better than anything. The 64M Flash Cart I can't convince myself to buy since Flash memory wears out eventually, even if it is some thousand flashes, I'd get there I'm sure. Plus I'd hate having to program it with a PC every time I want to change games as having only 64m of games isn't enough for me. I think it'd be much more convient to have a cart with RAM and load from a removable flash memory card. And perhaps make the RAM inside on a removable mini-pcb to allow replacement if it dies or is damaged.

Similar to the GBA Flash devices, people have seen how much more convient it is to get away from expensive NOR Flash memory for writing to conventional cartridges and instead using devices that load from Flash memory card into RAM. I'd love to have such devices for Genesis/32X, SNES, and perhaps some others like PC-Engine or something.

[fonzie]

just wait one month more, guys

[rbudrick]

[Trenton_net]

As someone already stated in simple form: It can't be done. When the Sega CD is attached to a Genesis the memory map gets totally changed. All games would be addressing information incorrectly, and you'd need to reprogram each game just to work on this new system. Save yourself the trouble and get a flash instead.

[rbudrick]

[kyuusaku]

I think it can be done with an external RAM cartridge, no modifications for games required (unless you want to save.) Either the RAM cartridge could start up with it's own ROM which communicates with the Mega CD on the register level, or it could start up disabled and boot from a Mega CD disc and make use of BIOS functions. If the device uses the Mega CD BIOS, then the cartridge would then need to assert the pin which prevents the Mega CD BIOS from starting [disable the BIOS which is in the ROM space (and WRAM too?)] and copy the ROM into RAM, from there it can run.

[fonzie]

http://www.sega-16.com/forum/showthread.php?p=19477#post19477