[dingaling]

Fascinating, here's the story from the programmer:

http://www.headen.com/XL1.htm

I'm not sure why he felt he had to write it all in machine code though, sadly he doesn't discuss that decision. Perhaps it was due to the time-dependency of the lyrics?

[ansible]

Without knowing the specifics of that platform, it is likely that the BASIC interpreter was not fast enough to generate the desired effects and animations.

[Angostura]

My guess would be quite simply to overcome memory constraints