Updates
 
3/26/08  Publish v1.0
 
Overview
 
Many older arcade games did not have the ability to save high scores.  There are many sites and many kits for hi score saving
but one is over due in my opinion...  Pac-Man.  There are multi-games out there that are great, but no plain high score mods.
The goal of this hack is to modify the Pac-Man board to save high scores and have it cost under $5.  A secondary goal is to
make the mod as simple as possible (design and implementation simple).  
 
 
 
Design
 
To satisfy the first requirement NOVRAM is out of the question, these things can get pretty pricy.  Serial eeproms are the way
to go here.  Granted they can not save as much information as NOVRAM and you need to write code to work with it, but you
can find them for around 10 cents in bulk (about $1 if you buy a couple of them).  I decided to use the 93C46 as used by the
Braze Technologies high score kits (http://www.brasington.org/arcade/hs/).  These hold 1k of data which is plenty for a page
high scores for Pac-Man.
 
To satisfy the second requirement the eeprom is the only chip I am adding to the hack.  it would probably be easier to install
if we put in a daughter card off the z80 or test connector, but I did not want to deal with adding other chips to the design.
One chip is is simple and we only need to make 6 connections.  If you want to get fancy you can make a little plugin board
but in this design you would need to socket the 74ls259 at 8K.
 
Which brings me to the next part.  How are we going to read and write to the eeprom?  I decided to borrow from two place.
One, my first Pac-man hack (http://www.souzaonline.com/Games/Hacks/4n1hack.htm) which uses 3 unused latches at 8K.
The second is JROK's Donkey Kong High Score save (http://www.jrok.com/sohs/dkong/DonkeyKongHighScoreSave.html).
 
Similar to JROK's design I am going to use the 74LS259 unused latches, luckily there are 3 open.  Note: You can not use
this hack with the menu driven 4-in-1 hack since it uses these latches to drive the game selection.  For the EEPROM output
I could not find any unused inputs, but I did find two unused dip switch inputs.  We can use one of these to read the EEPROM
output.
 
 
 
Connection Mappings
 

Pac-Man Board

93C46 eeprom

8K 74LS259 Pin (9)

Pin (1) CLK

8K 74LS259 Pin (10)

Pin (2) INPUT

8K 74LS259 Pin (11)

Pin (3) CS

8D 74LS365 Pin (14)

Pin (4) OUTPUT

8K 74LS259 Pin (8)

Pin (5) GND

  Pin (6) to GND
  Pin (7) NC

8K 74LS259 Pin (16)

Pin (8) +5

                Images

 
You can do something simple like piggyback the eeprom on the 74s259 or something simple.  I decided to make a little
daughter board as seen in the picture below.  All you need to do is get a radio shack pcb and wire it up and then socket 
the 74259.
 
                       
 
Modified Hack
 
 
 
 
Modified Eproms
 
   
 
  
 
Web Resources
 
http://www.jrok.com/sohs/dkong/DonkeyKongHighScoreSave.html
http://www.brasington.org/arcade/
http://www.souzaonline.com/Games/Hacks/4n1hack.htm
 
 
Thank You