I’m glad that you are here, David!
In the Z-machine standard, I read this (in the section on the screen model for version 4-8 except 6):
184.108.40.206: When the upper window is selected, its cursor position can be moved with set_cursor . This position is given in characters in the form (row, column), with (1,1) at the top left. The opcode has no effect when the lower window is selected. It is illegal to move the cursor outside the current size of the upper window.
Still, from reading the source of Robot Finds Kitten, I gather that the game splits off only five lines for the upper window (window 1), and then goes on to plot player, kitten and other objects on the sixth line and all the way down to the bottom of the screen. This seems to be illegal but nevertheless it works. Well, not in Ozmoo it doesn’t, because Ozmoo hides any attempts to output text in window 1 below the top five lines.
What’s happening here?