Is it possible?

[tru]

Not sure if this has ever been discussed before, I went through a few pages and didn't see anything...

Is it possible to increase the internal amount of save space on a Duo? Or is that pretty much set in stone?

Just asking because it would be cool to have save data for MM3 as well as save game data for other games without the need of outside devices...

[Opethian]

Saves data to a capacitor. I dont know if you can increase the size and have the system know there is more storage space. Even the tennokoe bank is the same SRAM size just 4 banks.

[thesteve]

you cant save data to a capacitor.
you can however save data in cmos ram maintained by a capacitor.

[vestcoat]

I'd really like to know if this is possible as well.  I think it's come up before but I don't recall anyone with technical expertise weighing in.  I'm guessing the hard part would be getting the games themselves to recognize the increased space available to them (might be the reason why the later Duo's never got a storage pump despite the generally larger save files for CD games.)

[TheOldMan]

I'd really like to know if this is possible as well.

Anything is possible, given enough time and resources

the hard part would be getting the games themselves to recognize the increased space available to them

Yep, there's part of the problem. You'd have to re-write the save-game code if you actually wanted it expanded seamlessly.
.............................................................................................
First, I'm -not- a technical expert, just someones who plays at it. With that said....

I could see adding more RAM Chips, and using a de-multiplexor chip to enable/disable the chips. You'd still be stuck with only 8K (2k? Whatever the save size is now) at a time, but you could have multiple banks, like the tennoke. And, if there are any 'free' addresses in the I/O area, you could, in theory, decode the address so that a write to the address would be latched, for use in decoding the BRAM page. It was actually a fairly common way of adding memory to older computers (pre-MMU), and the whole thing is probably where the mmu idea came from in the first place. The trick would be powering the latch so it retained the bank number when the pce was turned off

At least then you could select which page was used to save to. But you'd have to have software to set the bank number - which is why you'd need to keep power to the latch when you turned the pce off.

[nat]

It could be done, but the effort involved would greatly exceed the effort of buying a Tennokoe Bank.

[tru]

On that note, and thinking of the tennokoe bank... would it seem more feasible to add 3 more ram chips to the system, perhaps mount them in some fashion as to not damage the board at all and add a 4 way switch say on the side of the system so one could actually switch between 4  different banks and have the makings of an internal tennokoe bank card?

I am not a know how person to say the least, but if someone were to say this is how you would do it, I am a do-it-myself (following directions) type person... which is basically why I am asking this... I do think it would be nice to have extra save space available without the need for a converter/region mod in order to use the tennokoe bank card...

[SignOfZeta]

The region mod is like 1000 times simpler than the extra RAM and switcher you'd need for your plan. Plus, with a region mod you have access to a library much larger than the puny selection of US HuCards. Hell, you can barely run out of save space with The US library. It's too small!

[nat]

What Zeta said. By the time you actually had extra RAM added in a usable fashion, you would have been able to do 60 region mods. If the goal here is to save time, you're barking up the wrong tree.

[grahf]

The Ten No Koe bank is great and all, but I really wish you could copy individual save files between banks.

[tru]

What Zeta said. By the time you actually had extra RAM added in a usable fashion, you would have been able to do 60 region mods. If the goal here is to save time, you're barking up the wrong tree.

I wasn't sure how hard or time consuming it would be...  I don't have a region mod on my system, but I do have a converter and the tennokoe bank card... it is nice, I was just looking for something that could have perhaps saved time... again, just a thought... I will wipe the idea out of my mind now that I know a little more about it...

Thanks again everyone for the answers...

[nat]

The Ten No Koe bank is great and all, but I really wish you could copy individual save files between banks.

Agreed. I always wondered why they left that out.

[Bonknuts]

Not sure if this has ever been discussed before, I went through a few pages and didn't see anything...

Is it possible to increase the internal amount of save space on a Duo? Or is that pretty much set in stone?

Just asking because it would be cool to have save data for MM3 as well as save game data for other games without the need of outside devices...

 IIRC, a while back mednafen emulated BRAM as full 8k. It think it worked for most games. Only a few didn't like it. The way BRAM file system is setup, there's a pointer to the file allocations. There's nothing that says it can't point beyond the first 2k. And, IIRC, that 2k BRAM isn't mirrored... so it's open bus in the upper range. Maybe some games check for this assume a corrupt file and others just follow along and attempt load from the upper region. You could replicate this on the real hardware and add a switch to safe guard against some of the few games that have problems with it. It would be a rather advance mod though, but not undoable.