It's definitely an emulator thing with mednafen. I switched over to using the sys card bram routines instead,...
That sounds so damn familiar...I wish I could remember what we did to fix it...
First, check your mednafen.cfg file, and make sure its set up for bram saves; I vaguely recall if you don't specify a path for something, it won't actually save to a file.
Second, delete any old bram files you find. I do remember everytime I changed the cd image, mednafen created a new bram file (empty of course) with a different name. I believe the name was based on a hash of the code, and if things in the iso changed, you got a new save file.
Other than that ask the mednafen author what's going on / if he has any ideas. He's a pretty ok guy explaining why things do what they do. And if it's really an emulation problems, he does get it fixed.
Also, the CDREAD routine is annoying. I can only read in as many free banks as I have logical address range for (32k at a time)
The syscard 3.0 (?) CD_READ uses DH as a read type; the nice (or not) thing is you can specify an MPR bank to use for the read, and it is capable of filling consecutive banks for you.
And I -think- it may even load partial banks if the length isn't a multiple of 4 sectors.
Somewhere around there there used to be a HuCD7_final.pdf file that had the details on how the bios did things; not sure if it was 2.0 or 3.0, but the things it says do work on a 3.0 card.
That's how we figured out how to do MML
