nesdev.org

Edit: they are available now! See last post for details.



Hey group, I'm almost finished with a project and wanted to gauge the possible interest in it.

I think one of the main issues early on was the lack of the ability to install 32mbit DIP EPROMs (or bigger) inside the carts. Thus, the tsop adapter was a great solution (still is). A friend not long ago opened my eyes to the 27c322. They are cheap to buy, easy to program but they are massive and 16bit. Now with this adapter, they are easy.


This is a pcb that marries itself to the 1A3M (Lo rom) and 1J3M (Hi rom) carts and allows the use of 2 (yes two) of the massive 27c322 42 pin dip EPROMs. Both EPROMs can sit in sockets AND the cart shell closes normally. So it all fits neatly inside.

Here are the highlights:
This marries to the back side of a carts existing pins (see below pic). No need to remove the mask rom. The only hand wiring to do is to disable the mask rom by cutting its CE leg and tying it high to a 5v point.

Can be used with regular hi or lo rom boards
Can use it for the ExHiRom games too. (Tales of P, super Demo world, etc)

The nice aspect of this pcb is the sockets for the roms.
And yes, it will all fit inside the case (NTSC CASE. Haven't tried the SFC case)
EDIT: will fit in a SFC case too
The above pic shows a lo rom cart and I used headers to mount the pcb (so I removed the mask rom on this install).


This pcb has the 16bit to 8bit conversion IC's as well as a decoder (74xx139) for the ExHiRom games.
The roms don't have to be programmed in any special way. Just normal rom programming.
There are a few "SL" pads that you can solder jumpers to determine if its lo rom or hi rom or the ExHiRom. And there is also a selection for 27c160 EPROM usage too.
For the smaller games (27c160), the 29F1615 is a great flash rom to use. DIP package, cheap, fast program.

I made this to be a "anyone can do this" type of pcb. Yes, I know of the Buy-IC service using the Tsop flash roms. But what if the average guy with cheap programmer and average soldering skills doesn't have the necessary adapters to reprogram the tsop's? Just about every programmer on planet earth can program the 42 pin dip EPROMs. And with the socketed roms, just reprogram if you make a mistake on xxxxxx whatever game you are modding or translating, home brewing, etc.

There are 4 ic's and 6 caps. With a pencil tip iron, I have been able to solder the parts on with no trouble. The headers for socket use sink all the way to flush (note the BIG holes). This is why the roms and sockets can fit inside the case.
The remaining circuitry you see on the board is for future expansion and reset for game cycling.
With the reset button, you can now cycle through a variety of multi-game options. Anywhere from 16 games in 1 to a 2 games in 1. It just depends on how you want to stack your rom data.


The future expansion part is a work in progress.... But I'm hoping to get a tsop48/56 adapter made so that I can bank 4 x 32mbit games or more.... With an appropriate size tsop flash rom.

As I near the completion of this, I'm wanting to see how many of these I need to manuf. If there is enough interest, I may just have the fab house mount the parts. I don't want to do assembly... At least not on a mass scale.

I'll post a video sometime soon.
Thanks for looking!


Edit: the multi game feature works now using the reset to cycle between the games.

Here a link to a video.

http://youtu.be/eL5o8KmW21I


The multi game feature works great too.


Thank you Lidnariq for all your help!

This is pretty interesting. What would the cost be for a board with the components installed on it? Maybe good guess if you aren't sure. And would that include sockets for the EPROMs?

Also, how well does that generally work soldering to the legs of the MaskROM and MAD1? No connection issues or bad joints? Or do you need to take some care to clean them up before soldering? I do like the multi-game aspect too. Plenty of games would work well on a 2-in-1 or 4-in-1 or more type of cart.

Thanks. I don't know the price yet. Usually, the more I buy, the cheaper they are per piece.
I was thinking $10 for a bare board. I don't want to become an assembler of the parts.... I am hoping that I'll get a bunch of interest and I'll pay the fab house to install the parts. I could sell some assembled but I don't want that to occupy my time if LOTS of people want it assembled.
With a pencil tip iron, the SMT parts are pretty easy though.

I haven't had any connection issues so far. You do have to trim the legs of the SRAM and a few cap legs first before mounting. Cut them as flush as possible. Basically clearing the way for the board to mount to the back side. On my video, it shows one cart where (after I soldered the pcb on) I cut the mask rom off..... In hind sight, I probably should have left it on. There's a lot of strength with the mask rom still mounted.

This pcb also has the possibility of Star Ocean but a Tsop adapter would have to be used and sit where the mask rom is as the 3rd rom. I haven't tested this aspect of the cart yet.... But in theory, it should work.

Here's a pic of it inside a cut out shell.

In this final stage of design, I could make a 8 in1 multi. This would mean that on a 32mbit rom, the game sizes couldn't be any bigger than 512k.

Is this something that is desired or not?
Feed back please !

It might be desired if we ever decide to do a Super NES competition like the NES one that's ending in four days.

tepples wrote:It might be desired if we ever decide to do a Super NES competition like the NES one that's ending in four days.

I just tried a quick 8 in 1...

I just get a blank screen. I took A19,A20,& A21 legs from the EPROM...I programmed a rom with 8 different lo rom games - all 512k in size. I just stacked the data. I tied output 1,2,3 to A19,20,21 respectively.

The outputs of the counter:
SO is there some reason why a 4 in 1 works perfect (like in the video) but 8 in 1 doesn't? What am I missing here?


Edit: it works. Had a bad rom burn.

Markfrizb wrote:SO is there some reason why a 4 in 1 works perfect (like in the video) but 8 in 1 doesn't? What am I missing here?

What other variables are there?

The 3 high address lines are not connected to the snes buss.
They are all lo roms. None have headers attached.

I'll burn a different rom in a few hours. Maybe a new burn will work.

Could this do Zelda Ancient Stone Tablets, all 4 weeks?

Tormenter wrote:Could this do Zelda Ancient Stone Tablets, all 4 weeks?

I don't see why not. Are all the Zelda games less than 32mbits?

Is Zelda a lo rom model?

It's Lorom and 32Mb or 4MB each week. for the version with all bells and whistles.

flagoss wrote:It's Lorom and 32Mb or 4MB each week. for the version with all bells and whistles.

So all 4 weeks is 4 x 32mbits ? Or they all fit in 1 32 mbit rom?

It's four different 4 megabyte ROMs. You'd need four 27c322s to do it.

I see. Well, the "future expansion" that I referenced earlier will be able to do it.

I plan to make/use a Tsop56. 128mbyte satellite board. That's why rom1 has a 48 pin hole and the 4 SL's in the middle of the board would redirect the ripple counters outputs to the expansion section.
So, yes... It can do it in the near future.

Are there ANY Tsop 48/56 flash roms that are 5volt and 128mbits or 256mbits? I think 1 gigabit is the max size a tsop56 can be.

With a 256mbit rom, it would be able to cycle between 4 ExHiRom games (6-8 mbits each) or 8x 32mbit games.

If I have to use 3 volt parts, I can. It'll just mean the addition of level translators on the satellite board. This is why there is a 3v regulator already built into the pcb.

But more to the LoZ question. Since the roms are socketed.... Why not just burn the 4 roms and then pop them in as you progress through the game?

The only other possibility would be changing the design to let the ripple counter do a 2in1 (like in the video) but instead of choosing 2 banks inside 1 322, the 2 in 1 would choose between the 2 roms. But that still wouldn't get all 4 roms inside, not as dip parts.

Because I'm in final revisions with this design, any input is welcomed.