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Post by GiGaBiTe on Aug 3, 2010 2:52:27 GMT -5
How big does the RAM cart need to be?
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Post by jlf65 on Aug 3, 2010 5:08:06 GMT -5
4 MBytes (takes the whole rom space). Anything smaller would simply be a waste.
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Post by TheMVRules on Aug 3, 2010 14:08:35 GMT -5
The largest MCD flash cart by Sega was 128kB.
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Post by jlf65 on Aug 3, 2010 15:24:40 GMT -5
The largest MCD flash cart by Sega was 128kB. Not a battery backed up ram cart, a plain ram cart. And it would of course have to be a new thing... if a ram cart existed, I'd already have one. If I understand how the SCD works, you don't assert the CART line on the cart port. That allows the CD BIOS to boot and start the CD normally. The cart, however, is accessible at 0x400000 to 0x7FFFFF instead of the more normal 0x000000 to 0x3FFFFF where roms are. So you make a cart that doesn't assert the cart line and responds to 0x400000+ and has 4MBs of word-wide ram. It's actually not very hard of a design... it's getting them made that is the issue. Well, that and getting people to buy them. Something like this with a CPLD to serve as a level shifter, address decoder, and general logic for the board would be pretty nice.
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Post by GiGaBiTe on Aug 3, 2010 22:09:25 GMT -5
The largest MCD flash cart by Sega was 128kB. Not a battery backed up ram cart, a plain ram cart. And it would of course have to be a new thing... if a ram cart existed, I'd already have one. If I understand how the SCD works, you don't assert the CART line on the cart port. That allows the CD BIOS to boot and start the CD normally. The cart, however, is accessible at 0x400000 to 0x7FFFFF instead of the more normal 0x000000 to 0x3FFFFF where roms are. So you make a cart that doesn't assert the cart line and responds to 0x400000+ and has 4MBs of word-wide ram. It's actually not very hard of a design... it's getting them made that is the issue. Well, that and getting people to buy them. Something like this with a CPLD to serve as a level shifter, address decoder, and general logic for the board would be pretty nice. Most of us don't have a BGA reflow station I think a simpler solution would be to use 4 x 1 Mbyte 44 pin DIPP and wire it up on a prototype board with the necessary address decoder. The simpler the RAM cart is, the more people are able to build it. PCB etching kits are sold at almost all electronics hobbyist shops and are pretty easy to do.
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Post by jlf65 on Aug 4, 2010 2:23:00 GMT -5
Not a battery backed up ram cart, a plain ram cart. And it would of course have to be a new thing... if a ram cart existed, I'd already have one. If I understand how the SCD works, you don't assert the CART line on the cart port. That allows the CD BIOS to boot and start the CD normally. The cart, however, is accessible at 0x400000 to 0x7FFFFF instead of the more normal 0x000000 to 0x3FFFFF where roms are. So you make a cart that doesn't assert the cart line and responds to 0x400000+ and has 4MBs of word-wide ram. It's actually not very hard of a design... it's getting them made that is the issue. Well, that and getting people to buy them. Something like this with a CPLD to serve as a level shifter, address decoder, and general logic for the board would be pretty nice. Most of us don't have a BGA reflow station I think a simpler solution would be to use 4 x 1 Mbyte 44 pin DIPP and wire it up on a prototype board with the necessary address decoder. The simpler the RAM cart is, the more people are able to build it. PCB etching kits are sold at almost all electronics hobbyist shops and are pretty easy to do. If you make it DIY, it'll never get done. At best two or three people would make one. You need to do it like KRIKzzz is doing the EverdriveMD to have a hope of them being more of an oddity than anything else. It's why I'm doing a Myth version - I know from personal experience that there are at least a few dozen people with the Neo Myth for the MD. And, if anyone was interested in adding Myth emulation to a Genesis emulator, I could help with that. It's not really that tough. All the info needed is actually all open. Between what Drneo put up on the Neo Flash forums and my open source menu, Myth emulation would be easy to add.
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Post by TheMVRules on Aug 4, 2010 6:26:48 GMT -5
You could mod Gens with support, since Gens is open source. Then other emulator authors will be adding Myth support, just like with the SVP.
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Post by Tom Maneiro on Aug 4, 2010 13:51:10 GMT -5
You could mod Gens with support, since Gens is open source. Then other emulator authors will be adding Myth support, just like with the SVP. Please do it to Gens/GS And watch out for the buggy 32X core on Gens. As for Snake doing it to Fusion... unlikely, but since we're talking about unlicensed hardware, we may convince him... after all, it involves homebrew and unemulated gear.
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Post by jlf65 on Aug 4, 2010 15:16:03 GMT -5
You could mod Gens with support, since Gens is open source. Then other emulator authors will be adding Myth support, just like with the SVP. Please do it to Gens/GS And watch out for the buggy 32X core on Gens. As for Snake doing it to Fusion... unlikely, but since we're talking about unlicensed hardware, we may convince him... after all, it involves homebrew and unemulated gear. Good idea, guys. I can compile Gens/GS, and already did a couple bug fixes related to the 32X PWM (yes, I did submit them to gerbilsoft). That would also make quick testing of new Myth menus easier. I keep Gens/GS installed on my system, but can't use it for the menu since it needs the Myth hw.
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Post by GiGaBiTe on Aug 4, 2010 18:34:40 GMT -5
If you make it DIY, it'll never get done. At best two or three people would make one. You need to do it like KRIKzzz is doing the EverdriveMD to have a hope of them being more of an oddity than anything else. It's why I'm doing a Myth version - I know from personal experience that there are at least a few dozen people with the Neo Myth for the MD. I think more people would be interested in DIY RAM cart since it would cost a maximum of $30-40 to make one, compared to a Neo Myth which is $180-200. If we make a schematic and a parts list, it should be good for anyone to build it with simple tools. It could also be made by one of us for an additional fee and make a bit of money on the side
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Post by Tom Maneiro on Aug 4, 2010 19:26:38 GMT -5
Actually, you can find as litte as $140: www.ic2005.com/shop/product.php?productid=33&cat=0&page=1...but i suspect that S&H costs can raise the price up to $180 But on the other side, remind that with your NeoMyth you also get a built-in GBA/NDS flashcart, so... Back to the extra RAM: i already posted the suggestion to emulate it to Kega Fusion forums at Eidolons' Inn - let's see what Snake says about that. Getting emulator support for these would be very valuable, including developers
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Post by jlf65 on Aug 4, 2010 20:57:56 GMT -5
I think more people would be interested in DIY RAM cart since it would cost a maximum of $30-40 to make one, compared to a Neo Myth which is $180-200. If we make a schematic and a parts list, it should be good for anyone to build it with simple tools. It could also be made by one of us for an additional fee and make a bit of money on the side Throw a write-protect switch in the logic along with a switch on the cart line assertion logic and you have a simple "flash" cart that can be loaded from the CD. Sort of like MegaCart but with ram instead of flash rom memory. It COULD be really cheap, which is why I'm a little shocked no one has made one yet. What makes the MD Myth popular is all the things you can do with it: it's not just a flash cart capable of playing all MD and 32X games, but it's also a PBC equivalent allowing you to play (nearly) all SMS games as well. It also has both kinds of save ram and an FM chip for the SMS side. For a bit more money, you can also get a cart for the Myth that allows you to use SD/SDHC cards. I think a simple ram cart WOULD be popular, but you'd really need to keep the price down. If it reached $50, people would be put off as the cheapest flash carts are close to that price. Actually, I had an idea once - a Saturn to MD adapter. That would allow you to use the Action Replay Plus cart on the MD as a simple ram expansion (plus save memory with the proper code). You can get an ARP with 4MB of ram SUPER cheap, so if you can make the adapter super cheap, it stands a good chance of being popular.
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Post by Tiido on Aug 13, 2010 5:26:52 GMT -5
you got to find the Saturn cart connectors first... they're custom made...
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Post by jlf65 on Aug 13, 2010 15:38:03 GMT -5
you got to find the Saturn cart connectors first... they're custom made... Exactly. I looked around a number of times and found nothing. That's why it was just an idea that came to nothing in the end.
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Post by GiGaBiTe on Aug 23, 2010 17:00:45 GMT -5
Here's a 2 mbit RAM cart, just 30 mbits to go
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