Montezuma's revenge programming technique

[Nicola <anaddress@from.somewhere>]

Just a curiosity, if some of you can help...
Years ago, I used to play with Montezuma's revenge. I was surprised
how fast it was when loading and even more about the fact that it didn't 
use the disk any longer after startup (or, maybe, only when passing to 
next level, I don't remember). My astonishment was sharpened by the huge 
amount of rooms you had to explore (I never reached the end of the game, 
if any!) and by the unique complexity of each room.

In short, does anybody know about the programming techniques used by 
that game? (I know that it didn't load DOS 3.3 or ProDOS, of course, but 
nothing beyond that).

Thank you in advance.
Nicola