Hi Jim, and thanks for joining! I follow your excellent work on the wee MC! With regards to the block graphics, can they be displayed with a simple chr$(x)? are they part of the rom set? If they answer is yes, then they are perfectly fine mate.
Nothing on the screen is not a standard ASCII character. However, how each character gets there is not by CHR$. The city is just a PRINTed set of ordinary strings. And the missile tracks are put there by the SET/RESET commands, which selects the correct "block character" to display to give a "pseudographic" effect. So I'm still unsure. See: https://en.wikipedia.org/wiki/Semigraphics