saturn memory card design

I'ts increasingly difficult to find memory cards these days especially where i am, i was reading over some of sega's technical documents and was thinking, the memory card is just two 4Mbit chips that connect through a "A" bus connector, the accessing and writing and everything is handled by the console, so whay can't we just build some memory chips onto some PCB board with an appropriate connector to fit into the slot, as long as the memory chips were wired to the connector it should work,

If anyone could help i would apreciate it, a photo of the inside of a memory card would be excellent....please.please.....i know you think I'm crazy but what is there to lose.
There's a bit more. The memory cart has a few control ports used to query and configure the cartridge. See technical bulletin #47 for some info.
ok read it, can someone tell me what numbers are on the top of the set-register and refresh register and I would still love a close up of the intenals of a memory card...that would help me a lot....anyone with a digital camera and memory card...please please help me
I would have like to take picture of the internals of the memory card, unfortunately, to open it, it requires a special screwdriver, the same used on japanese PC Engine... ???
ive been thinking of a simliar project. becuz i already had 2 defect 4 meg carts, why not build my own? i still have the case of my ram cart(i went hulk on the board inside), couldnt i just plug 4 megs of ram into it and stick it in my saturn?
i would think the ram has to be compatible with the old one

mabey if you look up the number on the chip on the net you can find it or its replacement

usualy the replacements have the same pinout and follow the same instructions and all youd have to do is pop the old out and solder in the new

also the cards you have that are dead -- make sure none of the traces are bad (easy fix)
I found this on a link in the discussion forum...MWAHAhahahahahah, if anyone has anymore pictures to contribute or more detailed information of the insides of the cart....I'm sure we can pull this off

4Mb Ram cart internals

try right clicking on the link, chosing copy shortcut, open a new browser window and pasting the address into the address bar, that should work
I'm about 99.44% sure that the pictured board is identical to an EMS Action Replay 4M Plus without the Flash ROMs and commslink driver/connector. I've done some tracing of my AR 4M Plus: the two 74HC157s handle the address multiplexing for the DRAM, and the "2XEDJ-SS" chips seem to be 2Mx8 DRAMs that conform to the standard JEDEC pinout, each connected to one half of the data bus. The PALs probably handle the expansion RAM identification process and maybe some address decoding. Still, I think you wanted a backup memory cart, correct?

In a full AR 4M Plus, the chip position at the top would contain a bidirectional 8-bit buffer (don't have the part # right now but it is a standard 7400 series part, not hard to get at all), there would be a male DB25 connector at the very top, and on the right would be two Atmel AT29C020 chips, each connected to one half of the data bus. The AR firmware, which resides in the first 64KB of these flash chips, provides the other three of the "four" functions of the cart.

I've had a nagging interest in designing an uber-cart that would have cheat functions, direct-save backup memory, and expansion RAM, plus some extra debugging functions, so I'll contribute where I can, even if I don't get to say that it's my project.

edit: AR4M Plus uses two AT29C010 (1MBit), not AT29C020.
yeah i'm primarily trying to make a backup memory card but I'm keen to go futher if it works, and hey who cares who gets the credit as long as we eventually produce something decent, or some plans to make one so anyone with anything useful please throw it in, i was looking at that japanese site with lots of saturn modification info,


has anyone got an english translation of the pages
I love you people.

I've got a standard PAR and a 4-in-1 PAR; I can scan the boards on either one, if that would be any help to you.

For some odd reason, my 4-in-1 is broken somehow, and won't actually boot up as a PAR, BUT the 4 and 1 meg ram functions remain intact, so that's what I use it for....

I was asking about a similar device, bugging ExCyber about a Sega CD savecart...same theory, I suppose, but I heard its already been done!
yeah man pics of both sides of both cards and a list of the numbers and stuff on the chips on the board so we know exactly what is what, you may need some wacky tech tool to open it aparently...thanks heaps for whatever help you give
I'm pretty sure that section is RAM that's used by one of the onboard systems (either work RAM or VRAM probably). AFAIK the only thing that site shows regarding the save cart is a way to attach an activity LED to it.