[z-machine] stream/window interaction

[David Kinder]

> Stream 4: Um, are you allowed to do a read in the upper window? I don't
> think I saw anything about that in the spec either :)

You can: See "My Angel" from the 2000 Competition for an example.

> upper window. As it is, it's sort of both. (I suspect what's really
> happening here is that I don't understand OO analysis and design.

Analysis and design is like that: real computing problems do not in
general perfectly decompose into clean OO solutions, unlike the
problems in text books. That's software engineering for you :)

David