Ms. Pac-Man characters running out of maze

ELutz

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I've got a Ms. Pac-Man that's giving me fits. At random times, the ghosts will run through the walls of the maze...following their own little pattern. Usually it's just one ghost (none in paticular...I've watched them all do it at one point or another), though, on a couple occasions, I've had multiple ghost "outside" of the maze at the same time....the motherboard will reset in short order at this point. Sometimes it will happen on the first maze.....other times, I've made it to the fifth/sixth maze before a ghost goes "outside" the maze. I've also had the fruit bounce outside the maze a couple times...as has my Ms. Pac-Man character (though...it's usually one of the ghosts). I've also watched it happen in demo mode.

I've replaced a lot of IC sockets with no change. All ROMs are good...as is the processor, 2114 RAM, satellite boards, and Ms. Pac-Man daughter board...new ribbon cable also.

Here's the kicker....I removed the Ms. Pac-Man daughter board, popped the Z80 back in....and played Pac-Man fine (well, as fine as it can with Ms. Pac-Man character ROMs). I first figured something was up with the daughter board or it's ribbon cable. I threw a known working daughterboard on with new ribbom cable...same issues. I also replaced the Z80 IC socket...no change. I have since played over an hour of Pac-Man on this board without issues.....as soon as I put the daughterboard back on...I get my issues. I repeat...the daughterboard and ribbon cable are good (I also tested them on another working Pac-Man board...all good. So, any ideas what could cause this.

Thanks!
Edward
 
That's just a different ROM revision - it features free-range ghosts. It was created after complaints from ghost's rights activists.

:D

-Ian
 
That's just a different ROM revision - it features free-range ghosts. It was created after complaints from ghost's rights activists.

:D

-Ian

It definately makes for some interesting game play. If I eat one of the ghosts while it's "outside" the maze.....his eyes never go back to it's home to become a ghosts again. The eyes just stay in a looping pattern...one less ghost to get you. I managed to get three at once doing this....then the damn thing crashed :)

Edward
 
Let me check my notes when I get home this evening. I have ran across this at least once or twice before. FYI, its not going to be a socketed chip.
 
Interestingly enough I have a board on the bench right now doing something similar. Occasionally during the attract screen the ghosts and pac move outside or on the maze randomly. It doesnt do it during actual gameplay but the game has other glitches during a game like a couple missing dots which keeps you from finishing the level. I got to the intermission and it just hung and played the music over and over. Sometimes it reboots but mostly always on the intro screen as the characters are scrolling acorss the screen. This makes me think its some sort of rom addressing issue.
If I plug in an ABC board it plays just fine with no problems. This board was someones parts board at one time, should have stayed that way but I wanted a challenge.
 
I finally fixed mine.....6F ROM. It checksum-ed good. It CRC-ed good with maws.mame and Romident. I had already replaced it's socket. I burned a new ROM...problem gone. What I still don't understand.....as Pac-Man, the board ran fine...no issues. As soon as I added the Ms. Pac-Man daughterboard...I has issues.

Edward
 
Wish mine was that simple, I swapped roms earlier today since it worked with the abc board and was bypassing the roms.
I have seen boards run fine with a mspac daughterboard but wouldnt run as a pac....bad 2114 ram. I came across this issue twice.
 
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