There was a demo he did of NeXTSTEP where he coded some stuff (can't provide a link - work blocks streaming video). It's certainly possible that he memorized i

There was a demo he did of NeXTSTEP where he coded some stuff (can't provide a link - work blocks streaming video). It's certainly possible that he memorized it, but he didn't have any hesitations so I think he had more than a casual familiarity with it.