Huh, does it really have an MMU? I don't remember that when I coded for it back in the day, and wiki seems to be the only one saying that (uncited). It also doesn't make a lot of sense to be at that point in the system as it's so far away from the main bus matrix.

But perhaps my memory is going bad and my Google Fu is worse.

Edit: gbatek doesn't document an MMU in those cards either. https://problemkaputt.de/gbatek.htm#dscartexpansionram