Oh it depends a lot on which Ataris you had. My Mega STE had 4 MB (and even the old STs like the 1024 ST could have up to 4 MB), and it had 16 Mhz, and a Cache, *and* the blitter! One hell of a machine =)
But later machines, like the TT and the Falcon, could have up to (or maybe even more than?) 16 MB I believe, they had a 68030. And at lease here in Germany you could buy various 3rd party ST clones that were based on the 68040 and 68060 and had even stuff like PCI I believe (not sure about PCI, since I haven't been using ST since about the introduction of the Medusa, which was after the Falcon, I believe, so I don't know preciesely).
So, in theory, a port might be possible (esp. since SDL has a rather Ataris ST port. But without a proper system to test on, we can't do it.
And since EA bought us, I am afraid, the likeliness that any of us will do it is rather slime (0?). See
http://exult.info/announcement.html
