Re: [stella] Trick12

Subject: Re: [stella] Trick12
From: Erik Mooney <emooney@xxxxxxxxxxxxxxxx>
Date: Tue, 13 Mar 2001 22:00:25 -0500
On Tue, 13 Mar 2001 14:47:06 +0100, you wrote:

>You are not torturing me, as I KNOW how you did it. ;-) Since
>it seems to be confession time now, I think I can tell you that
>I've been playing around with the same code idea as you. But
>since I couldn't come up with a good way for displaying the missiles,
>I planned to use lightgun support for my game.

Wow.. that code is eerily similar to mine.  Although I put mine at the top
of RAM and you put yours at the bottom. :)  My code is able to do a
load/store for missiles, although I'm not quite sure how to make that
useful... I posted my source, have a look.

>I ran into the same problems as you. The gap before the second to
>last invader is one pixel smaller than the others. And since
>it is important when you rehit RESPx, you can't just replace them
>with stores to a RAM address, since that could destroy the trick
>and therefore the display.

I replace my stores with stores to a RAM address fine... I'm not sure what
you mean.

>We hadn't figured out many of the details of this trick when
>I was experimenting with the invaders game, so I couldn't
>come up with a nice way of removing individal sprites and I left
>it at that. But here is my marching invaders demo anyway for
>everyone to have a good laugh. ;-) It was designed on my PAL
>system, so you might need to force your emulator into PAL
>colour mode for the invaders to be green.

Your invaders are all ugly blobs, mine are much better :)  I've also got
single-pixel precision for the positioning, although yours replicates the
way the original moves one row at a time rather than the entire formation.

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