Making PAL Earthbound using 27C322

[MaarioS]

Hey there once again!! I'd like to build Earthbound cart using a PAL Hirom cart and one 27C322 chip. So first of all, would USA-NTSC version of Earthbound work on PAL cart or do I need some kind of patch or a completely different version of it?? Second, the size of rom doesn't match eprom's size. How do I solve that?? Do I need to extend it somehow?? I know that in NES games, the rom needs to me multiplied a few times until the EPROM is full, but is it also doable here?? Not to mention I don't know how to do it since the rom is 3MB when the eprom is 4MB so it needs 1MB of more data but what data??

Also, I've seen several times these schematics on this forum and I assume you also sure did, but they differ a little.... One of them tells me to connect SNES /CE to GND while the second one tells me to connect it to 74LS139....
http://www.image-share.com/upload/2605/22.jpg
http://sega4ever.power-heberg.com/tutod ... 20cart.png
So which one is correct?? Or do they all need some kind of correction?? Would you tell me how to exactly connect it?? Please for reply. Big thanks in advance for any kind of help, I'd be so grateful!!

[Markfrizb]

You should consider my adapter...
viewtopic.php?f=12&t=11120&start=30#p130289

I posted a good working schematic on the forum not too long ago.
viewtopic.php?f=12&t=4877&start=45#p124330

[MaarioS]

You should consider my adapter...
viewtopic.php?f=12&t=11120&start=30#p130289

I posted a good working schematic on the forum not too long ago.
viewtopic.php?f=12&t=4877&start=45#p124330

Thanks for your suggestions but here you showed how to build it with 74LS139+257+257. Well what's the difference between this setup and 74LS139+245+245?? I'd rather make the second one since this seems more legit to me anyways

[Tormenter]

What do you mean by "more legit"? Its a repro, nothing legit about it =)

[MaarioS]

What do you mean by "more legit"? Its a repro, nothing legit about it =)

You're 100% right!! Well what I meant to say is the method of making it, not a repro itself. Maybe I should have used the word "more promising" method, that's more correct

[mikejmoffitt]

I believe you'd want to duplicate the last 1MiB of the 3MiB rom to fill the 1MiB void left over.

So the 4MiB rom would be filled like this:

[Normal 3MiB Rom][Last 1/3rd of Rom] = Full 4MiB Concatenation

[MaarioS]

I believe you'd want to duplicate the last 1MiB of the 3MiB rom to fill the 1MiB void left over.

So the 4MiB rom would be filled like this:

[Normal 3MiB Rom][Last 1/3rd of Rom] = Full 4MiB Concatenation

That's what I also thought too, but shouldn't you fill it with the FIRST 1MB of data?? That's the question that needs answering

[tepples]

Games with a non-power-of-two ROM size (10, 12, 20, 24 Mbit) will typically have one chip larger than the other, with the larger chip lower in memory space. For example, 24 Mbit is usually one 16 Mbit chip and one 8 Mbit chip. The 8 Mbit chip ignores the highest address line, causing its data to appear twice in the memory map.

[MottZilla]

Typically games do not rely on proper mirroring in that example. The only games known to rely on it are Mega Man X and Demon's Crest which do so for copy protection measures. It is the safe thing to do however to fill the empty space with what would normally be mirrored there. It is highly unlikely to matter in this case. But you may as well do the safe thing and mirror that data.

[MaarioS]

So basically, are you able to program a 3MB game on 27C322 (4MB) EPROM?? Since 3MB are my biggest pain because when I deal with 1-2MB games, I easilly use 2x 27C080 (or some other combinations like 080+040 etc.), for 4MB I use 27C322 and for 3MB games I'd also like to use 27C322 because using 3x27C080 would be just so cruel....

[tepples]

So basically, are you able to program a 3MB game on 27C322 (4MB) EPROM??

That'd be a yes. Just double up the last megabyte.

[mikejmoffitt]

As long as we're here, I have been meaning to take my Mother 2 cart and make a bilingual cart, allowing for a switch to control which bank is in use (JP or US ROM). It sounds like I will need 2 27c322s to switch between. I had thought the game was 2MiB, but apparently it is 3.

[Markfrizb]

You should consider my adapter...
viewtopic.php?f=12&t=11120&start=30#p130289

I posted a good working schematic on the forum not too long ago.
viewtopic.php?f=12&t=4877&start=45#p124330

Thanks for your suggestions but here you showed how to build it with 74LS139+257+257. Well what's the difference between this setup and 74LS139+245+245?? I'd rather make the second one since this seems more legit to me anyways

I think the lower pin count was the main difference why I chose the 257's. Why would one switching IC or the other make any difference as being more legit ---design wise -- or not? My set up works. I've seen pcb's with the 245 ic's work too. In experimentation, I tried mine without the '32 ic (ORing the OE and CE for the 257 switch enables) and it worked as well. Even though the 257's work without the OR ic (32), I was advised to use the 32 anyways as a -- just in case there is a buss conflict, you should do this-- and the ic was a small 5 pin so it didn't occupy too much pcb real estate. That being said, I've seen working repo pcb's that don't use the 32 at all (when using the 257's). And my own tinkering, I've bypassed the 32 ic on a few of my adapters and everything I've thrown at it has worked so far, including saves. Since my adapters can use 2 27c322's in sockets, it's been easy to test different game setups (extended Hi rom games or multigame) and not worry about a bad burn or whatever.....

Edit: I don't know if the 245's would be the same, but with a buffer (125 I believe), I can mix 8 bit and 16 bit roms. The buffer would control the 257's enable line to either run the 16bit roms or turn off the 257's so a 8 bit rom would run (like the 29F032's) mixed in with the 27c322's. more tinkering that I was doing to see what was possible....