Trying to make a game, but requires 256k sram. I have the 256k off a mario paint. Can I swap the 64k on the madden out with a 256k, or will it need rewired? Thanks
You will need to rewire it.
Pin 01 goes to A14 instead of 5V
Pin 26 goes to A13 instead of RESET
Otherwise it should be the same.
Thanks, but im fairly confused. According to the link below, there are no A13/A14 on the madden boards?
http://nintendoallstars.w.interia.pl/romlab/sram64.txt
You wire them to the MaskROM's connection (bend up pin 1 and 26).
Ahhh ok, bend up pin 1 and 26 on the 256k chip, and wire it to mask rom A13/14 correct?
Yea. Is there a capacitor between Pin 1 and 28 for the old SRAM?
Ice Man wrote:
Yea. Is there a capacitor between Pin 1 and 28 for the old SRAM?
Not sure. Will take a look this afternoon. I still can't get it going using this below:
http://nintendoallstars.w.interia.pl/romlab/hirom.htm
This is just a comparison between LoRom and HiRom. You can tell by the PCB Label.
SHVC-1JxM-xx or SHVC-1JxB-xx is HiRom.
SHVC-1AxM-xx or SHVC-1AxB-xx is LoRom.
Number can differ. It depends how many MaskROMs are on the PCB.
Edit: May I ask which game you are trying this with?
Ice Man wrote:
This is just a comparison between LoRom and HiRom. You can tell by the PCB Label.
SHVC-1JxM-xx or SHVC-1JxB-xx is HiRom.
SHVC-1AxM-xx or SHVC-1AxB-xx is LoRom.
Number can differ. It depends how many MaskROMs are on the PCB.
Edit: May I ask which game you are trying this with?
Madden 95. I wire the maskrom up like normal for the game, then the sram I remove, and I replace it with the 256ksram, lifting pins 1 and 26. Afterwards, I place a wire from pin 1 of sram to A14 (SNES cart pin 39), and wire from pin 26 of sram to A13 (SNES cart pin 38). Turn the game on, plays fine, just does not save. I tested the battery with a multimeter and it is holding strong at 3.06v. The PCB board number is: SHVC-1J3M-11, HiRom
Hmm, would you mind posting a photo of the front and back side of the PCB?
Could it be that there is nothing wrong with the SRAM and how it's wired but rather, a game programming issue?? Example: Chaos Seed will boot to the intro with 256k SRAM but it won't go past the intro. But when I have it in a cart with only 64k SRAM, it works perfect.
Ice Man wrote:
Hmm, would you mind posting a photo of the front and back side of the PCB?
sure! I had this one laying around with nothing on it.
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An issue could be the internal header or a checksum protection that prevents the game from doing certain actions such as booting, saving, etc. Best example would be Metroid and Earthbound.
Either way, the board looks fine but I wanted to see the finished board, not the empty board.
Aside from chip pinout incompatibilities, there might be involved what copier users used to know as "SRAM checks" in a game. This was a software-based protection that checked whether a more-than-needed amount of SRAM was available by reading from <SRAM_size>+1, then comparing the result to <SRAM_start>+1, and going to a trap loop (or silently doing malicious things instead, like Earthbound did) should the result of the comparison be negative. This is because SRAM was usually mapped to "wrap around", that is, the byte beyond e.g. 64 Kbit of SRAM normally mirrored the memory cell of the first byte of said 64 Kbit, so if the comparison resulted in a difference, then there was likely a copier being used to play the game. (Most copiers used to have at least as much SRAM as retail cartridges with the highest amount of SRAM known at the time had, i.e. most copiers were equipped with 256 Kbit of SRAM.)
@Tormenter, in your case though, I would assume that there's an issue related to bad wiring. A few years back, I accidentally soldered a 256Kbit SRAM chip into a defective Soul Blazer cartridge that I wanted to revive. After my repair attepmt, the game played fine but wouldn't save, no matter how often I tried. Only when I realized my mistake, and put a 64Kbit chip in there instead, did it finally work as expected. And it still does unto this day, as the cartridge is part of my personal collection.
So it all boils down to this: You might check your wiring once again.
Another issue can be the capacitors though. I had to experience that on my own when the first (usually NC or GND) and last pin (5V) weren't connected to the capacitor nearby.
Then again, a 256kb SRAM has A14 for Pin 1, which should just normally connect to A14 on the MaskROM. Important is that 5V is directly grabbed from the last SRAM hole.
Ice Man wrote:
Another issue can be the capacitors though. I had to experience that on my own when the first (usually NC or GND) and last pin (5V) weren't connected to the capacitor nearby.
Then again, a 256kb SRAM has A14 for Pin 1, which should just normally connect to A14 on the MaskROM. Important is that 5V is directly grabbed from the last SRAM hole.
Gotcha, here is the board:
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I have never worked with 74HC257 before, only with 74HC245 and 74HC139 to make 16bit EPROMs compatible with 8bit SNES board. (I wouldn't mind knowing how this works though).
Either way, don't solder directly onto the cartridge connectors. Use the pins from the old ROM instead.
A14 should be pin 31 if original MaskROM has 36 pins or pin 29 if it is 32 pins.
http://nintendoallstars.w.interia.pl/romlab/snesroms.htm
Iceman, I posted a schematic of how to use the 257's not too long ago....
But here it is again.... The header is if you use a 27c160 EPROM so it can use both...
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Tormentor, Your board looks very familiar.
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Sometimes when you solder to the cart edge, it'll short out to the connector. You should run your jumpers to the mask rom pins
Thank you. I just recently joined and haven't looked at every forum yet.
I like the idea of those adapter boards. Are there any eagle or gerber files for them?
Either way, let me know if it still won't work or works now when resoldering A13 and A14 from SRAM.
viewtopic.php?f=12&t=11120#p127181You can read more about them here....
No eagle files. Sorry. I hear a lot of good things about Eagle... I need check them out
Ice Man wrote:
I have never worked with 74HC257 before, only with 74HC245 and 74HC139 to make 16bit EPROMs compatible with 8bit SNES board. (I wouldn't mind knowing how this works though).
Either way, don't solder directly onto the cartridge connectors. Use the pins from the old ROM instead.
A14 should be pin 31 if original MaskROM has 36 pins or pin 29 if it is 32 pins.
http://nintendoallstars.w.interia.pl/romlab/snesroms.htmGotcha, so what about the other pin that is lifted that goes to A13, would be pin 30 if I am reading that correctly?
Tormenter wrote:
Ice Man wrote:
I have never worked with 74HC257 before, only with 74HC245 and 74HC139 to make 16bit EPROMs compatible with 8bit SNES board. (I wouldn't mind knowing how this works though).
Either way, don't solder directly onto the cartridge connectors. Use the pins from the old ROM instead.
A14 should be pin 31 if original MaskROM has 36 pins or pin 29 if it is 32 pins.
http://nintendoallstars.w.interia.pl/romlab/snesroms.htmGotcha, so what about the other pin that is lifted that goes to A13, would be pin 30 if I am reading that correctly?
Correct, mask rom pin 30 is A13
Umm still can't get it going. Tied it to old mask rom, then tried on the diagram mark posted using those A13/14. The game works fine, just won't save. One time I did rewire it, and when I put it in, the continue option was highlighted, but when I tried to load from that, it stated the save data was lost.
Are you still trying to run that madden game? Maybe you should try a game that normally uses 256k SRAM. Like SIMM City 2000 .... I believe that's a high rom, 256k game...
Have you checked for continuity from the cart edge to the SRAM chips address and data lines? If any of your solder pads are broken, then it wouldn't work.
I'll have to do the mod you are talking about and see if it works for me.. But I did do a similar mod using a 1mbit SRAM... (32pin) and I was able to get it to work without too much effort
Markfrizb wrote:
Are you still trying to run that madden game? Maybe you should try a game that normally uses 256k SRAM. Like SIMM City 2000 .... I believe that's a high rom, 256k game...
Have you checked for continuity from the cart edge to the SRAM chips address and data lines? If any of your solder pads are broken, then it wouldn't work.
I'll have to do the mod you are talking about and see if it works for me.. But I did do a similar mod using a 1mbit SRAM... (32pin) and I was able to get it to work without too much effort
Not sure what you are talking about about continuity etc hehe. The game plays fine, the saving part is the issue though. I know none of the pad's were broken when I installed the new sram chip. It works fine with Sim City 2000, thats how I got the copy I use working. Trying to get this one going for my brother.
I have already modded a game to use 128kb (1MB) instead of 8kb (64KB) and it saves fine.
I assume the problem is the connection between SRAM and MaskROM.
Continuity means that the connection between those two works without any problems. Those single sided soldered boards are very easy to destroy because the solder pads oftenly fall off when they are too hot, sadly.
If you have a continuity tester you can check the connections between them.
If your multimeter doesn't have a separate button for continuity, is an ohmmeter (low numbers = continuity) OK?
Markfrizb wrote:
Are you still trying to run that madden game? Maybe you should try a game that normally uses 256k SRAM. Like SIMM City 2000 .... I believe that's a high rom, 256k game...
Have you checked for continuity from the cart edge to the SRAM chips address and data lines? If any of your solder pads are broken, then it wouldn't work.
I'll have to do the mod you are talking about and see if it works for me.. But I did do a similar mod using a 1mbit SRAM... (32pin) and I was able to get it to work without too much effort
Cool. Let me know the results =)
On HiROM boards, SRAM is mapped to offset 6000h-7FFFh in bank 30h-3Fh.
Knowing that, address lines always being A13=1, A14=1, A15=0 on SRAM access, why do you wire your SRAM to A13 and A14 ???
nocash wrote:
On HiROM boards, SRAM is mapped to offset 6000h-7FFFh in bank 30h-3Fh.
Knowing that, address lines always being A13=1, A14=1, A15=0 on SRAM access, why do you wire your SRAM to A13 and A14 ???
He wants to upgrade from 64k SRAM to 256k on a 1J3M cart. Wouldn't A15 = 512k SRAM?
Since his cart started life out as a 64k SRAM, it only has trace/buss connection up to A12 from the address buss. He wants to increase his SRAM to 256 so he need to wire the 2 additional address lines to the buss A13 and A14.
I think in HiROM, RAM A14 and A13 need to be wired to A17 and A16, skipping A15-A13 the way LoROM skips A15.
tepples wrote:
I think in HiROM, RAM A14 and A13 need to be wired to A17 and A16, skipping A15-A13 the way LoROM skips A15.
Yes, you are right. I just metered a hi rom cart and a lo rom cart both having 256k SRAM.
The hi rom cart, SRAM A13 ---> Rom A16
SRAM A14 ---> Rom A17
Tormentor -this is the answer to your problem.
A Lo rom cart SRAM A14 = Rom A14
SRAM A13 = Rom A13
Markfrizb wrote:
tepples wrote:
I think in HiROM, RAM A14 and A13 need to be wired to A17 and A16, skipping A15-A13 the way LoROM skips A15.
Yes, you are right. I just metered a hi rom cart and a lo rom cart both having 256k SRAM.
The hi rom cart, SRAM A13 ---> Rom A16
SRAM A14 ---> Rom A17
Tormentor -this is the answer to your problem.
A Lo rom cart SRAM A14 = Rom A14
SRAM A13 = Rom A13
Will give her a shot tomorrow sometime. Thanks!
Okie that was one of the suggestions before it appeared, as I had those marked on the board already, but gave it a shot again and still not working. I tested the battery itself and its at 3.06v
You have to have a broken trace somewhere then. With A13/14 being correctly jumpered to romA16/17, and the 256k doesn't use a CE2. I believe the /WE position is unchanged as well as the /OE and /CE. So what is left is the possibility of a broken trace or a bad SRAM.... Or a bad MAD1 i.c.
Markfrizb wrote:
You have to have a broken trace somewhere then. With A13/14 being correctly jumpered to romA16/17, and the 256k doesn't use a CE2. I believe the /WE position is unchanged as well as the /OE and /CE. So what is left is the possibility of a broken trace or a bad SRAM.... Or a bad MAD1 i.c.
A13/14 is pin 1 and 26 of the 256k correct?
Ive got one board left, ill give it a try soon
Well if I get it correctly, if you want to use a 256k SRAM and use it as 64k, why don't you just simply connect A13 & A14 straight to GND??
The 6264 (8Kx8 SRAM) has positive chip enable (+CE) on pin 26 and nothing (NC) on pin 1. The 62256 (32Kx8 SRAM) uses them both for address lines. So as long as the surrounding circuit doesn't connect the +CE input to anything other than Vcc, you can use a 62256 instead of a 6264 by lifting and grounding pins 1 and 26. But I'm guessing that some carts connect /RESET at the cart edge to +CE to help prevent stray writes during a power cycle.
Here is how I got my high rom 256k sram cart to work. Don't mind the jump on pin 17 of the sram as it is not needed. This was for Brandish 2 using a Madden cart, I'm not sure if others are the same.
http://imgur.com/AF0iWr7