Bug in Ms. Pac-Man (original 7800 version)

[PacManPlus]

Hello all:

 

After looking at the code of Ms. Pac-Man, I noticed that GCC did the same thing in the 7800 version of Ms. Pac-Man that they did in the arcade version. In doing comparisons with levels, they used BMI and BPL instead of BCC and BCS. This means that and 'lucky' person who gets beyond level 127 will start to notice strange things. I kind of made a 'cheat' in the standard Ms. Pac-Man game like the 'rack advance' of the arcade game and found this (it will happen in this order):

 

- It will all start off with the 7 fruit being replaced by the cherry only at the bottom of the screen (because of the fruit drawing routine being affected first)

- The monsters will no longer all come out at the same time, and will exit the pen in the same manner as the first board

- eventually, the fruit that comes out will be replaced with garbage graphics, and will be worth anywhere from 0 to over 200K points.

- The energizers will begin to work again, and will vary greatly from board to board how long they will last

- Finally, some odd speeds between you, the monsters, and the blue monsters. Some will cause you to hesitate, move, hesitate, etc.

 

I didn't see what happens when you 'roll' the level counter over from 255-0, I did this when I couldn't sleep and was finally tired. But I imagine the fruit, speed, and energizer would start over - but the boards would remain as the last two sets.

 

Unfortunately, being that I 'borrowed' code from Ms. Pac-Man for Pac-Man Collection and Super Pac-Man, they will suffer from the same 'enhancements'. But, if nobody in 20+ years has reached that level, chances are nobody will.

 

 

... see what happens when you can't sleep? :-P

 

Bob

Edited November 3, 2008 by PacManPlus

[Artlover]

Hello all:

 

After looking at the code of Ms. Pac-Man, I noticed that GCC did the same thing in the 7800 version of Ms. Pac-Man that they did in the arcade version. In doing comparisons with levels, they used BMI and BPL instead of BCC and BCS. This means that and 'lucky' person who gets beyond level 127 will start to notice strange things.

Interesting.

 

Tobad I've never been able to get even remotely close to that high. I've got to level 10 once.

 

I kind of made a 'cheat' in the standard Ms. Pac-Man game like the 'rack advance' of the arcade game

Bin please.

 

Or atleast tell me which bytes hold the level, and I'll hexedit it myself.

[PacManPlus]

Sorry about the delay, I forgot I even posted this

 

Here is the bin - the only thing I changed, is that I added a 'Rack Advance' switch (like the arcade). The Left Difficulty switch should stay in the 'A' position. When it's flipped to the 'B' position (F6 in Prosystem), it advances the rack. I picked 'B' instead of 'A' because ProSystem defaults to 'A' which means you would have to sit there holding the 'F6' key if you wanted to play the game.

 

Enjoy the odd behavior after level 127

 

Bob

mspacman.A78

mspacman.bin

[Artlover]

 

Thank you.

[shadow460]

I will definitely try to get that far. I can knock out 20-25 levels on a good day.

[PacManPlus]

BTW, there is another bug I found in the original Ms. Pac-Man.

 

If you eat an energizer as the last dot to clear the maze, when you get the next maze the monsters remain in 'scatter' mode for as long as the energizer would have lasted, in addition to the normal 7 seconds.

 

[+Trebor]

BTW, there is another bug I found in the original Ms. Pac-Man.

 

If you eat an energizer as the last dot to clear the maze, when you get the next maze the monsters remain in 'scatter' mode for as long as the energizer would have lasted, in addition to the normal 7 seconds.

 

 

COOL. Never realized that all the years of playing the game on the 7800.

 

-Trebor