I'm not sure if it's just me doing something wrong, but I'm having an issue where saving is actually impossible on FDS Zelda 1. It works fine on Metroid and Zelda 2, so it's not like FDS games can't save at all or anything like that.
It doesn't matter what I do; as soon as the emulation is stopped, save data is gone. If I do a Hard Reset instead, the game will remember the save data still in memory, but that doesn't really help anything because it'll still be lost once the emulation actually stops.
A difference I've noticed between those games that might be relevant, is that Metroid and Zelda 2 ask you to swap back to disc Side A when you save, while Zelda 1 always stays on Side B past the title screen. Maybe BizHawk has trouble with games that save onto Side B or something, but I don't know, I'm not an expert, and I don't know which other games function that way to try that out.
There are workarounds for sure, for example save states work, and the cart version also works, but it'd be a shame to have to rely on save states when regular saving exists, and FDS has that sweet sweet FDS audio that the cart version doesn't have.
I'll probably just end up sticking to the cart version, but I wanted to bring it up still just in case there's a real issue, so it at least has a chance of getting fixed for those who may care.
Also, this is in BizHawk 2.3.1; I also tried almost every version all the way back to 2.0 and it doesn't work on any of them either. I'm not sure how much I want to go through so many 1.x versions though, so I didn't try any of those.
This is for both v1.0 and v1.1 disks, CRC32 1F22CCB1 and 8F2202BF as per No-Intro.