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Posted byitchyNADZ
Posted on07/05/08 00:09 AM



No enemy fire trick

On either the 1st or 2nd screen, leave one of the
blue/yellow bugs, from either of the 2 left-most columns in
the formation. Avoid its fire until it stops (and passes
at least 3 times down the screen without firing). This
takes anywhere from 5 (if both are left) to 20 minutes to
perform. This bug occurs b/c the jobs of starting a new
shot and moving an existing shot are handled by 2 different
CPUs (there are 3 total). The problem is, each uses a
different method to determine if a shot is active or not -
one checks to see if X=0, the other uses a specific status
byte. There are a total of 8 shot slots that can be active
or not at any time. When you leave one of those bugs, it
circles off and on the screen. If it shoots while off the
screen, the shot is made active, but X=0; it never moves.
When this happens 8 times, their shots become inactive. In
a 2-player game, if either player does the trick, both will
benefit.

My friends and I always wondered why this worked back when
Galaga first came out. Now I know.




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> I know your message has a bunch of text in it to read, but for some reason my
> eyes just cannot focus on it.
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Entire Thread
Subject  Posted byPosted On
*Explanation of Galaga 'no fire' bug  itchyNADZ07/03/08 10:07 AM
.*Re: Explanation of Galaga 'no fire' bug  Ooga07/03/08 06:13 PM
...Here  itchyNADZ07/05/08 00:09 AM
.*Re: Explanation of Galaga 'no fire' bug  EMU-LMAO07/03/08 12:30 PM