Yeah, "experimental" may not be the right word, but actually getting to use the 3-1 split required all of the following: at least 3GB of physical RAM (obviously), the O/S booted with /3GB flag, and the application in question linked with /LARGEADDRESSAWARE flag (and not mishandling the high bit of a pointer). Many video games towards the end of the 32-bit era were built this way tbf, though they still generally do better on 64-bit Windows/Wine anyway.