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Playing Genesis ROMS on Mega CD + RAM Cart
Devil Ken Masters - Jan 21, 2003
  Devil Ken Masters Jan 21, 2003
I have bought recently a Genesis copier, but it's 16 meg only and loading games from disk is really boring specially because I've to copy games from PC to disks (and because I've not been able to make it work already, but that's not the point).

I've thought about the idea of someone making the diagrams for a RAM cart to use with Sega CD to load games.

I explaing myself.

Time ago I've seen a Eeprom or similar cart for Master System that can be homemade.

A RAM Cart could be cheaper because of RAM beeing cheaper than EEPROMS, specially if they can be reused from old RAM pc chips, think that I don't know if should be possible because I have not enough electronics knowledge at all, I'm only suposing.

Then, the idea is making a SEGA CD program that when you put it in on Sega CD it let you select a game from a list, it loads it from the CD onto the RAM cart and then let you play it.

I know that it should be really difficult to code that program and it to work with a homemade RAM Cart (and it to work aswell)

I only want to know if anybody ever thought about a thing like it or tried something similar.

 BTails Jan 22, 2003
If you'd have looked above the SegaCD forum title, you would've seen this.


  
	
	

		
		

			There is NO WAY to play genesis ROMs on SCD, DON'T ask.


I think that should help.

 Devil Ken Masters Jan 22, 2003
BTails, I've read the Sega CD forum title, have you read my post?

The title of this forum means that there is no way to use ROMS with Sega CD and Genesis ONLY, a question oftenly made because of the Mega compilation CD appeared by Sega. I know that there is NO way and I know why, because Sega CD Ram isn't enough to load an entire genesis cart game. My question includes a homemade RAM CART in the idea (if you bothered to read it), not SEGA CD with Genesis only.

And I really know that probably nobody will ever try to do nothing like this, but please, don't come with answers like that if you have not read my entire post. Thanks.

 ExCyber Jan 22, 2003
IIRC, this is possible. The main "gotcha" would be that you'd need to have hardware in the cart (which could just be a switch, but that would probably be annoying) to change the state of the CART_IN signal. This signal controls the mapping of the cartridge and Sega/Mega CD hardware: if it's low, the cart is mapped to 000000-3FFFFF and the SCD/MCD is mapped to 400000-7FFFFF, if it's high/floating the mapping is reversed. You'd need to put the cart at 400000 for loading the game, and then put it at 000000 to run the game.


  
	
	

		
		

			. I know that there is NO way and I know why, because Sega CD Ram isn't enough to load an entire genesis cart game.


Actually, the main reason is that the Sega CD RAM is not mapped to the same address range that a cartridge ROM would be in, so any absolute ROM address references in a Genesis game would point to the wrong place.

 Devil Ken Masters Jan 22, 2003
Thanks for the answer Ex Cyber and for the info about ROM adresses not beeing the same in SEGA CD RAM than in a cartdrige, this is the MAIN reason for sure, I said that the reason is the games couldn't fit, but probably the most small ones could, and then the principal problem is the one you said.

I wish someones tries this project, it could be fine

 mal Jan 22, 2003

  
	
	

		
		

			Originally posted by Devil Ken Masters@Jan. 23 2003, 10:27 am



I wish someones tries this project, it could be fine


Keep on wishing...