Your memory's going, I'm afraid. The original version, the BBC Model B one, used a novel split-screen technique. The upper larger portion showing space was Mode 4, 1bpp at 320 × 256 if it was the whole screen, the bottom flight-deck portion was Mode 5, 2bpp at 160 × 256. Here's a screenshot, http://upload.wikimedia.org/wikipedia/en/c/c4/BBC_Micro_Elit...

You are right. The upper screen was definitely black and white, but the bottom in colour: http://www.youtube.com/watch?v=cQ6PjWP34Kg

In the BBC B Master edition the top was in colour. I always was jealous of my friend who had one, since it had so "much more" memory! :-)

No, you're right, the version shown is the second processor edition.

The pick of the bunch is probably the Master 128 edition, as it sports colour AND double buffering, though it won't be as fast as the second processor edition on account of the missing processor:

http://www.youtube.com/watch?v=ZEbhsXIL8a8

(I don't think there's a Master 128 second processor edition, sadly, but if there actually is, that one would be even better.)