Tried it on the PV1000 multicart I've designed (TinnedTrace.wordpress.com)
Sadly doesn't work on real hardware.
so cool! ( https://tinnedtrace.wordpress.com/2025/04/27/casio-pv1000-controller-and-multica... ) - i'm curious "seeing" it working there as well
Well it acts as if there is no cart in the slot. Z88DK had the same issue, which has now been solved.
Might be useful:
https://github.com/z88dk/z88dk/issues/2726