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8k Atari Pac-Man

Nukey Shay

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Flashing maze:

This is a quick edit...so there might be a few bugs attached to it. What I've done here is rather than reset the maze once one is cleared, I bumped the fruit timer down to a value of $FF. So once the display is drawn, the program checks this value. If it's not $FF, the program continues normally...otherwise, it skips over all movement and just updates the timers. Once the frame counter rolls over, the fruit timer is cleared and the program continues :)

In the display portion, I also check this value when the kernal is updating the screen colors. If it's $FF, bit 4 of the frame counter is LSR'ed and merged with the maze color.


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  • 2 weeks later...
  • 2 weeks later...

That happens because I don't know what value I should be using for the countdown timer when exiting the title screen display kernal :( The original game never used one, since it jumped right to the game board when the program boots.



The fruit timer is reset once the intro tune finishes (it was popping up on the screen too quick on the first board)...and the points value is reset to display for 128 frames once it's eaten (sometimes, this would not be displayed at all).

The board flash is corrected


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I played this a lot, got a few suggestions and comments.


First off, very nice work, especially the collision detection.

2nd of all, is there a way to change up the ghosts' ai? The patterns work, and even though the new ghost comes out while the rest are still blue, they're still running from you, not chasing you.


That is all.

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I still don't know how the AI works exactly...there's subroutines being jumped to and stack return addresses being PLA'ed off everywhere! :x


I did find an area where the player's X and Y locations are either copied to temps OR reversed and then copied to temps...which might make sense (in other words...the ghosts are always "chasing", it's just that they are chasing inverse locations which makes it appear as if they are running away).


Another odd thing about the original program is that the player Y location is set up to be saved as an inverse...but it never is :? The lower few lines set up a new value for the accumulator, but the accumulator is loaded at LFA99. So I added an additional STA to the program.

Any idea why those lines were even there? Dennis?



      LDA    pacmanX                ;3 copy player location to temps

      STA    kernelPFValues+1       ;3

      LDA    pacmanY                ;3

      STA    kernelPFValues         ;3

;       LDA    currentPlayerVars+18   ;3 energizer active?
;       BPL    LFA82                  ;2 branch if not

;changed...allow ghosts to run away seperately

      LDA    objectDirections,X     ;4

      AND    #$04                   ;2 check for blue flag

      BEQ    LFA82                  ;2 branch if not blue

      LDA    pacmanX                ;3 use inverse locations instead

      CLC                           ;2 (i.e. run away)

      ADC    #$60                   ;2

      EOR    #$FF                   ;2

      STA    kernelPFValues+1       ;3

      LDA    pacmanY                ;3

      CLC                           ;2

      ADC    #$B1                   ;2

      EOR    #$FF                   ;2 ...not saved??

;added (missed in original game??)

      STA    kernelPFValues         ;3

      JMP    LFA99                  ;3


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  • 4 weeks later...
Okay and is there anyway to re-hack an already hack Pac-Man game with a better looking maze? Here's my idea mockup maze I use from a screenshot from one to four^_^


You've seen "Hack'em", right?


He's talking about Raindog's Pac-Man Arcade getting further tweaked to get it closer to the original arcade game's "wire-frame divider" maze look and all.

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Yeah, I knew that much. Just suggesting that much (not all) of the goals that were suggested for the hacking were already dealt with in Nukey's "Hack'Em".


As for re-hacking the pac-hack of Ms. Pac, at least some of it is possible, me not knowing much about the code itself. Hollowing out the maze walls should be possible, depending on how the playfield data is handled. Changing the color of the dots or door to the ghost house is less simple, and probably not possible in a way that looks like those mockups. the playfield color would have to be changed for the scanlines with dots, so slits would have to be cut through the maze walls at those lines to keep the colors from striping them. (look at either of Nukey's Pac-hacks to see that done.) Same pretty much goes for the ghost door, either that or use a missile or something to look like part of the playfield.


In any case, only hollowing out the maze walls sounds like something that could be done by a casual hacker. The rest would take some extra work.

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  • 3 weeks later...

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