Re: R: [stella] a thing that doesn't let me sleep...

Subject: Re: R: [stella] a thing that doesn't let me sleep...
From: Piero Cavina <p.cavina@xxxxxxxxxxxxx>
Date: Tue, 26 Aug 1997 23:04:23 +0100
At 20:46 -0400 25-08-1997, Erik K Mooney wrote:

>>> >...how could they put seven aliens per row in Atari Galaxian?

>I did some experimenting, and it turns out that I can get up to ten
>copies of one player on one line, though the tenth copy extends past the
>end of
>the line and overflows to the beginning of the following line.

>You might be able to run the code in RAM, and each frame alter some
>of the STA RESP0 lines to something harmless like STA $80... this
>would let you turn on and off each graphic individually, but there's no
>time to change GRP0 between copies.

Very tricky. Could the self-modifying code + STA RESP0's technique have
been used for "Communist mutants"? There's a lot of sprites in that game.

The only disappointing aspect of all this, is that I can't see many uses
except for a formation of aliens in a vertical shooter; and there are
already some very good games in this category.

However, you've done a very good job unveiling another Stella secret. It
would be nice if all this kind of information would be organized in
documents (like it has already been done for other subjects: the
Supercharger, "How to draw a playfield", the sound registers...).... any
volunteer? :-)

Ciao,
 P.




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