I wasn't talking about the Carnivore 2. See the mapper used for Deva: RBSC_Flash_KonamiSCC. If I remember correctly, RBSC can also provide these with other mappers. It's flash based, so you can use (part of) it to write data from your game. Just like Deva does.
We could add a variant of the RBSC flash cartridge.
https://www.msx.org/wiki/RBSC_Carnivore2 ? Not sure if that would help me. How?
I'm currently working towards a proposed design of a megarom cartridge (with 8kB nvram), like this:
Just as ASCII16, but if bit 7 of the segment number is set, nvram will be present.
This is the same setup as for ASC8 Royal Blood & Wizardry (SRAM of 8kB), just that it is 16kB segments... Sounds like a combo that should not be too hard to get in openmsx. If I could get openmsx to compile maybe I could even do it myself - but me and win32, c++ projects almost always goes badly :(
We did consider programmable mappers, but we couldn't come up with something that could cover all current mappers, without getting immensely complex.
Yes, looking at the variations on this page https://www.msx.org/wiki/MegaROM_Mappers, this seems a bit complex, yes. But if you leave out the anti-piracy mapper, and split out SCC to be partly hardcoded as today, it might be doable. But then again... what are the benefits of implementing this compared to other features and time available? I see that this might not be top priority.
If I'm not mistaken you need more than 4GB ram and 64 bits Windows to compile Openmsx, even if you are trying to compile a 32 bits version of it, perhaps that's why you had issues.
Are you working on a megaflash cartridge with ASCII 8/16K mapper and with 8kB nvram ?
I'm not an electronics engineer, but I'm in contact with one, and ASCII16 w/8kB nvram is the working thesis for the cartrige version of Lilly's Saga right now, yes
You can see how to build openMSX by doing something similar as is done on the GitHub Actions... or just read the Compilation Guide.