Eeproms and burning them - what are the limitations?

Skykid · Post by **Skykid** » Thu May 08, 2008 7:38 pm

I'm asking because I don't know much about Eeproms n stuff, but here's the scenario.

Scenario 1:

I own a Japanese copy of Seiken Densetsu 3 on the Super Famicom.

I want to open the cart, find the relevant chips, and burn the fan sub rom so I can play it in English, and on my Super Famicom console.

Is this possible?

Scenario 2:

I own a US/EURO Final Fight PCB, and want the relevant chips burned with the Japanese romset so I can see Jessica in her bra?

Is it possible?

Thanks for the help!

RGB · Post by **RGB** » Thu May 08, 2008 10:05 pm

You can literally 'create' every game for the snes, even those consisting of special chips like a SA-1 or S-DD1.

For the SD3eng you will need four 27C080/801 eproms (it's eprom, not eeprom) and an address decoder (74xx139). Obviously it requires some additional soldering to be done, as eproms pinouts are not the same as mask roms on the game's PCB.

IMO the best donor cart for the SD3 would be a Donkey Kong Country, as it has 2 mask roms inside, and a sram. That makes the whole process a hell lot easier, as you don't have to look for space inside the case to fit additional eproms. You just place two eproms on the top, and two on the bottom (piggyback them). The only disadventage of this donor, is its sram memory. It is only 2KB (6216) in size, while we need 8KB (6264) for the SD3.

I will try to find some photos and schematics for you, as I even had my own website devoted to this stuff

Skykid · Post by **Skykid** » Fri May 09, 2008 12:14 am

Brilliant! Although most of that is a little beyond my understanding, it's nice to know someone has some knowledge about this. Gonna PM you about your site dude.

iatneH · Post by **iatneH** » Fri May 09, 2008 12:18 am

Skykid, you may want to look into the flashcarts made by Tototek. Also, various 3.5" floppy disk-based solutions are available.

Skykid · Post by **Skykid** » Fri May 09, 2008 9:40 am

Hey iatneH,

I'm not interested in flashcarts etc - I'm well aware of the different possibilities of playing the Rom file. Ideally I'd like an original SFC version of Seiken 3 that plays in English on the Super Famicom console. That's the goal!

Fenrir · Post by **Fenrir** » Fri May 09, 2008 10:11 am

Do it!
Call it SEIKEN DENSETSU 3 USA PROTOTYPE 1.0 BY SQUARESOFT JAPAN NEVER RELEASED L@@K RARE and sell it on Ebay.
You'll make bucketloads of money

RGB · Post by **RGB** » Fri May 09, 2008 10:34 am

Fenrir wrote:Do it!
Call it SEIKEN DENSETSU 3 USA PROTOTYPE 1.0 BY SQUARESOFT JAPAN NEVER RELEASED L@@K RARE and sell it on Ebay.
You'll make bucketloads of money

Indeed, the last one I saw on ebay fetched ridiculous high price of 500$...
I truly despise those who put up homemade carts for sale on ebay, not because that's illegal, more like because they take money for something they didn't do - translation patches. Translations are brought to life by fans for fans, for free to everyone.

That's why I HAD a website with how-to's...

Skykid · Post by **Skykid** » Fri May 09, 2008 1:44 pm

Lol, and there was me thinking I'd touched on a brand new idea, only to find out its been done already. If there's any doubt, I'm not interested in re-selling, it's just for the convenience of having an english lang version in my SFC collection.

I never realised these existed on Ebay. Not that I'd pay a retarded price like that for one, the job itself is probably fairly simple (as RGB's site no doubt detailed.)

But Ebay is a place for suckers anyway, as we've seen illustrated recently by these:

When I saw that some guy actually bought these Zelda promo posters for these prices, I couldn't believe my eyes. Sure, they're older posters (and nice too), but they're not even B1. The price is a joke, someone should contact that Shockwave guy and ask him what planet he's on!

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0034814333

And a Gamecube Windwaker promo poster for...£60!!

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0034814339

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0034814345

iatneH · Post by **iatneH** » Fri May 09, 2008 6:11 pm

I gave my suggestion still based on the premise that you would purchase an original SFC cartridge. Since you will be playing something unofficial, I thought it might be in the better interests of the collector to do so nondestructively. Anyway, do what you like...

Skykid · Post by **Skykid** » Fri May 09, 2008 6:31 pm

iatneH wrote:I gave my suggestion still based on the premise that you would purchase an original SFC cartridge. Since you will be playing something unofficial, I thought it might be in the better interests of the collector to do so nondestructively. Anyway, do what you like...

I'd aim to make it as non-destructive as possible - invisible to the naked eye.

iatneH · Post by **iatneH** » Tue Jun 03, 2008 3:25 am

Er, funny enough, I'm getting into this now

What games make good donor carts? I picked up a NFL Quarterback Club '96 cart for $3 because it was one of the cheapest things I could find, there is one 36-pin mask ROM, and battery back-up with a 16K SRAM (edit 2: wrong, it's 2 KB).

Is the circuit board layout for the ROM part significantly different from a game with just a 32-pin mask ROM? Should it be OK to just solder in a 32-pin socket in its place, shifted over 2 spots?

edit:
It also has a MAD-1 chip. Looks like I will also need to add a 74HCT139?

edit 2:
Is it possible to swap out the SRAM for something of a higher capacity? If yes, can it be bought as a standard IC or will I need to cannibalise another SNES cart?

RGB · Post by **RGB** » Tue Jun 03, 2008 7:52 am

I'd recommend a different donor cart, just because that NFL has got 2KB of sram, which is not sufficient for the most of better games. Still, if you've got not much experience with this stuff, then this cart is something you can practice on and see how you're doing

The circuit board layout for the rom is slightly different comparing to the eprom pinout, thus some rewiring is required or changes on the board (like cutting and joining appropriate traces).

Mad-1s job is to decode more than one memory on the board. It maximally joins two rom memories and a sram. An external decoder, like for example 74139 is only used when you want to join 3-4 roms.

You can swap the sram from the board for whatever 8bit, 5V static memory, like 6264, 62128 etc.

iatneH · Post by **iatneH** » Tue Jun 03, 2008 4:02 pm

Thanks for the information. I was not really interested in playing any of the "better" games at the start, I was not counting on ending up with a SRAM cart but I will take this one to the end.

I also got a NHLPA '93 which just has one mask ROM, this will be simple to work with for older action games not requiring multiple EPROMs or SRAM, right? (Take THAT, EA Sports)

iatneH · Post by **iatneH** » Wed Jun 04, 2008 8:01 pm

Whee, double post. Instead of buying a replacement SRAM chip, looks like I can just get a NBA Live '95 cartridge for even cheaper. Seems to be a good cart to use, 2 mask ROMs and 64 KB SRAM.

I will just be looking around a local used game shop. RGB do you happen to know any other (cheap) suitable donor carts I should be looking for?

RGB · Post by **RGB** » Thu Jun 05, 2008 7:15 am

Sorry for no answer the other day, I was busy -_-

RGB do you happen to know any other (cheap) suitable donor carts I should be looking

Yes, I recommend you the following games:

HiRom type + 8KB sram
-Illusion of Time
-NHL 95
-NHL 96
-NHL 97
-Secret of Evermore
-Sim City 2000 (it's got a 32KB sram)
-Donkey Kong Country (it's got two mask roms, but only 2KB of sram)

LoRom type + 8KB sram
-FIFA Soccer 96
-FIFA 97
-FIFA 98
-NBA LIVE 95 (two mask roms inside)
-NBA LIVE 96
-NBA LIVE 97
-NBA LIVE 98

iatneH · Post by **iatneH** » Fri Jun 06, 2008 5:43 am

Thanks a lot, RGB, your information came just in time. I went out and bought two carts today according to your list.

Here is what was formerly a NBA Live '96:

I am still waiting for my programmer, eraser, and EPROMs themselves to be delivered though, so I have no idea if I did this correctly yet.

iatneH · Post by **iatneH** » Sun Jun 15, 2008 12:18 am

Going to hijack this thread again.

Upgraded the regular old socket on my NHL '93 cart to a 32-pin ZIF socket, so now it is trivial to change EPROMs. It adds a huge amount of bulk though so I have to use a cartridge adaptor with the cart, and I even had to cut away a small part of the adaptor as well. Also, I had to move one of the capacitors onto the other side of the cartridge PCB.

ZIF sockets are totally awesome. I am going to do this to my NBA Live '96 cart later.

iatneH · Post by **iatneH** » Wed Jul 16, 2008 5:38 am

RGB wrote:HiRom type + 8KB sram
-Donkey Kong Country (it's got two mask roms, but only 2KB of sram)

Whee triple post.

So I got a DKC cart off eBay, a funny thing is that there was only 1 mask ROM inside! Luckily I have a personal copy from way back with 2 mask ROMs, so I swapped the PCBs and began my attack...

It's not working! I have done a 8 KB SRAM replacement but I don't think that's the problem. I suspect it may have to do with the OE pin for each EPROM. As I understand, the address lines are all duplicated across to both EPROMs, but the CE and OE lines must be separate?

Originally, the OE lines of the mask ROM were connected to pins 1 and 16 of the MAD-1, so after cutting, I reconnected the EPROM OE back to the same two MAD-1 pins. What is strange is that this page says that these two pins should be NC in a HiROM game? Also I noticed that the two CE lines are connected together as well, I guess this is OK as long as OE is only high on one EPROM at a time? I've checked and re-checked my wiring and I can't see any mistake...

Then there is the problem of whether I split/burned the EPROMs correctly... It's a 12 Mb HiROM, I split to 8 Mb + 4 Mb, and the joined pieces have a correct checksum, and both EPROMs were verified after programming...

It's got to be a problem in the hardware... Help!

Skykid · Post by **Skykid** » Wed Jul 16, 2008 9:47 am

You haz PM!

bitkid · Post by **bitkid** » Wed Jul 16, 2008 12:00 pm

Why are you opposed to using flash carts? IINM you can install them in a regular SFC or SNES cartridge shell.

RGB · Post by **RGB** » Wed Jul 16, 2008 12:51 pm

DKC is a 4meg game with two mask roms, it means that mad1 decodes them and gives one more address - which in this case works as A21.

You have to cut off the trace from pin 13 of the mad1, and connect the pin with the address A20 on the cart connector/hole from the old mask rom, because you have a 2meg game here.

iatneH · Post by **iatneH** » Wed Jul 16, 2008 4:06 pm

Thanks so much, RGB! That did the trick. You have been a huge help time after time here, I really appreciate it. I think I understand this hacking thing a little bit better now too.

bitkid wrote:Why are you opposed to using flash carts? IINM you can install them in a regular SFC or SNES cartridge shell.

Of course I thought about it too, but last I checked, Tototek SNES carts are out of production. I waited too long, so I am left with this option, which is still quite fun and satisfying.

RGB · Post by **RGB** » Wed Jul 16, 2008 4:18 pm

Hey, no problem!

I'm glad that it worked for you