Hmm, this is actually a quite complex question, and there are many reasons why I don't want to add save feature on Pseudo Saturn Kai :
1. Most important reason : save support on flash device may potentially brick your cartridge : flash chip life length is measured in write count, so rewriting the same flash pages (as it done when adding saves on Action Replay cartridge) may damage your cartridge.
There is the same problem with Pseudo Saturn Kai when accessing saves on SD card, but SD card life length is longer, and in the worst case this can be easily fixed by changing defective SD card to another one.
Memory Cart Plus way of managing save (= directly from game to cartridge flash memory) is technically great, but because of this flash life length problem, Memory Cart Plus
is reputed as "weary, flaky", etc, so I don't want to repeat this same mistake with Pseudo Saturn Kai.
2. Direct save from game to cartridge flash memory (as Memory Cart Plus does, but Action Replay doesn't) is technically difficult to implement.
The reason is that the code that manages direct save to cartridge runs directly from cartridge ROM (because nearly all the Saturn's RAM is used by the game itself), and that flash chip can't be read a short while after being written.
One workaround would be to put only the flash write code in the few RAM provided by game for backup library, and let the remaining as-is in ROM, but this is technically difficult to do.
3. I don't want to add Action Replay hardware specific code in Pseudo Saturn Kai.
I did enough Action Replay hardware specific work when making Pseudo Saturn flasher utility, and don't want to do more.
The only reaction to Pseudo Saturn from Action Replay manufacturers was to ... raise Action Replay price. If at least they could contribute something to Saturn users community (example : release Action Replay source code, or send a donation to yabause or Pseudo Saturn team), my way of thinking would be different ...
4. There are few remaining space in flash memory, because Pseudo Saturn Kai firmware is relatively large.
Well, a lot of text/graphics data are optional and I suppose that some unused code could be also cut off, but I prefer to keep Pseudo Saturn Kai as-is rather than making some minimal (= "cheap, dull") Pseudo Saturn Kai in order to free room for save data.
But there is also one reason I want to add save feature on Pseudo Saturn Kai for Action Replay :
5. Saves recorded from Action Replay firmware are lost after flashing Pseudo Saturn Kai.
This is particularly sad because there's no major place where Saturn save data are available for everybody, and I suppose you don't want to re-start playing from your favorite game's level 1 after upgrading your Action Replay to Pseudo Saturn Kai.
Currently, the only solution to keep your Action Replay save data if you want to upgrade to Pseudo Saturn is to copy them to Saturn internal backup memory before upgrading, so you probably won't be able to save them all.
Technically speaking, I can make a "lite" save data support for Action Replay cartridges.
By "lite", I mean that :
- I will be read-only : only saves selected before flashing firmware will be available.
- It will be small : around the same size as Saturn internal backup memory, or even smaller.
And "I can" doesn't means "I will" : this "lite" save data support shouldn't be difficult but may however require some time to implement and test, hence I should verify first if people are interested in it before developing such feature.
Please let me know if you're interested in such "lite" save data support.