Can a Pacman/MsPAcman converted to Jr Pacman using JrPacman ROMS

[francoisadt1]

I do have a Ms. Pac-Man PCB I want to convert this to a Jr. Pac-Man Game.

What must be done to convert from Ms. Pac-man to Jr. Pac-Man?

Can I buy the Jr. Pac-Man roms and install this into specific ROM slots on the MsPacMan main PCb or Daughter Board to render and play Jr. pac-Man?

ROMS are program code after-all?

Will the Jr. Pac-Man ROMS fit into the size/type of Ms. Pac-Man ROMS chips slots?

Which mspacman roms must I swop with which jr. pac-man roms?


Regards
FdT

[meyer980]

You'll probably want to do some more research but here's what I found.

The Jr. Pac Man ROMS don't share a parent in the MAME romset or appear as a clone - which typically means it's not just simple romswap from some other game.

That said though, the thread found here: https://forums.arcade-museum.com/showthread.php?t=395525
seems to indicate there was both a field and conversion version of this game which determine which harness it is compatible with. Since you're using a Ms Pac Man board (presumably with a Ms Pac Man cabinet) you don't need to worry about the harness as much - maybe you can just do what you're saying and replace the ROMs? I took a look at the two roms though and really none of the location names match up.

Solvalou shows all of their ROMs as unique, for what that's worth: https://www.solvalou.com/arcade/roms/J/jrpacman

Long story short, I don't think it's a simple rom swap. Someone with more knowledge (or maybe the guys over on KLOV) might know better though.

[francoisadt1]

Thanks for the ROM comparison,

Can someone explain how does the Roms execute?
Each ROM do something have logic and read write to ram addresses for input and output, is this correct?
So if each rom do some logical purpose why then one slot in another game have its own logic but just read write to same ram execution  blocks?
Like a plu n play? So the the PCB do have mspac or pacman spesific instruction flow not in the Roams but in burned inthegreeenboard What will happen if one put Roms in a PCB that are different than the original? Will the pcb get burned or low up? So ROM is not just program code?

[PL1]

Can someone explain how does the Roms execute?

Simple version - the microprocessor (a Z-80 in this case) reads the program code, graphics, etc. from the ROMs; runs the program code; and outputs the display and sound.

Pac and Ms Pac used the same board/layout, so you can convert one to the other by changing a few ROMs and adding/removing the Ms Pac daughterboard.

With Jr Pac and Ms Pac, you're dealing with different PCBs laid out in different patterns with different chips and different size ROMs with different numbers of pins.  There is no way to convert between these with a simple ROM swap.

Ms Pac board (click for full-size)


Jr Pac board (click for full-size)


If you look along the along the top edge of the boards you'll see numbers (column) and along the left edge of the boards you'll see letters. (row)

The names of many MAME ROMs use the column/row to identify the location of the chip that holds that data.
- IIRC some may use a schematic designation like "U7" that is silk-screened on the PCB or some other means to identify a particular chip's location/function/data.

For example:

The first Jr Pac ROM listed at the solvalou link that meyer980 posted earlier is "jrp8d.bin" ==> column 8, row D ==> the ROM chip with the bright white label just right of center, third from the bottom.

The graphics ROMs are "jrp2c.bin" (2C) and "jrp2e.bin" (2E) ==> the two in the lower left with labels.

The sound ROMs are "jrprom.7p" (7P) and "jrprom.5s" (5S) ==> top center-left without labels.


Scott

P.S. You can barely read the markings to confirm, but the 40-pin Z-80 microprocessor is at 8B.