Installing 11.1: which boot image?

I'm about to cold-install 11.1 from cd. However, I'm presented with a choice of 2 boot images, labeled "no emulation 0" and "no emulation 1".

I thought it would wait for me to choose, but not so: after 30 secs or so it defaulted to 0 and is now slowly ---very slowly--- booting. I can't discover any mention of what those images are or, of course, whether 0 was the right one. I expect I'll find out eventually, but does anyone know so that I can save time?