Houston, we have lift off
I did a quick merge of the rest of the 4K SpaceWar! 7800 code so now the ships move & fire again. Of course there were problems - the main one being top-to-bottom wrap around. Turns out there was a bug in the 4K version, it didn't handle it properly either. Although the code wrapped around the display list pointers correctly, it didn't handle the end of display list index correctly. Thus, it tried to add the sprite to display list 0 using index 25, wiping out the display list. Ick!
I still want to do some cycle counting and see if there's any possible optimization of the display list builder. I should also zero out the display lists at startup to prevent MARIA from going runaway if the active screen starts up before the display lists are built.
Then I need to make a list of features to add to make the "game" itself. One of the ideas I'm toying with is an energy counter. Rotation/Thrust/Fire would deplete your energy (which would slowly replenish, but maybe make that an option). Hmm... how to handle regeneration? Would you come back with a full tank?
Of course, kill counters & SFX are on the list. I don't think a one player mode is in the cards unless someone can come up with a reasonable AI. I'd also like to do some kind of title screen, but that's low priority.
Oh, I'll also slow down the starfield so it's more of a slow drift.
I'm also working on some sample code skeletons for other budding 7800 homebrewers. Watch AA and the mailing list.