Pacman Freeplay / High Score Save

[philmurr]

Pacman was the only game in my collection that I didn't have a high score save kit for. I've spent a few lunchtimes recently disassembling Pacman code and finding out how it works. Quite different from Galaxian/Scramble etc. untidy in places but still nicely put together.

This has allowed me to build a "proper" freeplay/high score save mod (at least one of the mods out there isn't integrated too well, and, for example, stops inserted coins being registered when the high score table is displayed. Others don't keep the "random" number generator the same so ghost patterns are different). The other thing is that I don't want to pay out around £70 to fit one to my game...

No fancy menus, freeplay is selected from the coin DIPs and maintains attract mode when in freeplay setting.

Saves top 10 scores / 3 initials each to serial EEPROM, reset them to default by pressing "joystick up" on power-up.

Displays the high score table as part of the attract mode.

Uses the same Z80 high score PCB as my other kits (Galaxian, Moon Cresta, Astro Blaster, Kung Fu Master)

Photos showing it in action from real hardware and mame are below

 

[Lardonate]

Very nice! Been meaning to get one of the kits for Ms. Pac myself but just not got round to it due to the £70 plus whatever the customs man wants to whack us with!!

 

[r-type]

Top work!

 

[smarty]

Nicely done Phil.

 

[PAC-MAN]

Very cool Phil, top job as always.

 

[Valtric59]

A very good project.

The question of the day : after the millions points, when the game is over.......What will show the "ranking".....

 

[Phils Arcade]

Do you disassemble ROM code or from MAME files?
Would be interested in how you go about it.

 

[philmurr]

A very good project.

The question of the day : after the millions points, when the game is over.......What will show the "ranking".....

I'm sure you know pacman uses 3 bytes to store the score and at a million it rolls back to 0. You will appear in the high score table only if (your actual score modulus 1 million) is high enough. So if you score 1,000,100 it will treat the score as 100 and it's unlikely to get you there. I could have changed this to recognise the millions but chose not to.

Do you disassemble ROM code or from MAME files?
Would be interested in how you go about it.

I disassemble the ROM code and use mame debugger to help. Then test what I can in mame but there are some parts of the daughterboard such as the serial EEPROM driver that I can only test on hardware. Disassembling is the only way to really understand the code, and to make the mods look as "original" as possible. Here's a snippet of my disassembly

 

[Phils Arcade]

Very good, love the old way, always brings back memories of just how hard coding used to be

Z80/Z80A and 6502 was my first intro into coding way back in the day. Still have my original Z80 coding book.

 

[Kevv]

I might be overlooking something, but do you sell this kit or share the ROMs for this so we can use it?

 

[philmurr]

I might be overlooking something, but do you sell this kit or share the ROMs for this so we can use it?

I occasionally make a batch of them and sell them, or bare PCBs are available most of the time for people who want to DIY

Send me a message if you're interested in any particular kit

 

[kingtreelo]

is this something we could use in mame, i often play pacman at home and would love this

 

[philmurr]

is this something we could use in mame, i often play pacman at home and would love this

Unless you change the MAME driver to include the hardware in my kit, then no