Altirra implements a single floating bus by default for 800 and XE hardware profiles and has an opt-in for 800 dual floating buses (Memory > Enable floating I/O bus). The only game I know of that requires that is Warhawk. Quick way to distinguish is to run a BASIC program that prints PEEK(54528) in a loop; it'll mostly print 255 for no floating bus, 213/0 for an XL/XE floating bus, and 212/0 for an 800 floating bus.
    • Like
    1