Re: [stella] Horizontal movement routine in Donkey Kong and Space Jockey

Subject: Re: [stella] Horizontal movement routine in Donkey Kong and Space Jockey
From: Manuel Rotschkar <cybergoth@xxxxxxxx>
Date: Sat, 08 Nov 2003 14:42:04 +0100
Hi Dennis!

> While disassembling I see that Garry is using a 
> similar horizontal position routine that Manuel found 
> in Battlezone! I also saw the same routine in Garry's 
> first game Space Jockey.

Way cool discovery!

>LF5A4: STA    WSYNC   ;3
>       SEC            ;2
>LF5A7: SBC    #$0F    ;2
>       BCS    LF5A7   ;2
>       EOR    #$0F    ;2
>       ASL            ;2
>       ASL            ;2
>       ASL            ;2
>       ASL            ;2
>       ADC    #$90    ;2
>       STA    RESP0,X ;4
>       STA    WSYNC   ;3
>       STA    HMP0,X  ;4
>       RTS 

Cool is the ADC at the end which allows easy shifting 
the complete range to some extent.

> Now I wonder if Garry came up with this routine. He 
> says he programmed Space Jockey by disassembling some 
> Activision games. So far (to my knowledge) none of the 
> disassembled Activision games use this routine.

Hm... I'd be really curious to know some of the names 
behind CCE. It can't be anything other but rogue 
Activision or Atari programmers, can it?

> Anyway, I thought it was interesting so I thought I'd 
> pass it on.

I think it's interesting to see such advanced techniques 
in games with such a bad reputation. Certainly adds to 
speculations that they where crippled on purpose :-)

Hm... can any of you guys do a grep over all 2600 
binaries for this exact hex sequence:

e9 0f b0 fc 49 07 0a 0a 0a 0a



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