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Ms. Pac-Man step by step
08-11-2018 at 09:09 AM
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Ms. Pac-Man Original PCB and Bootlegs



When it comes to the actual video game arcade circuitry, Pac-Man, is actually quite simple. The Pac-man PCB (printed circuit board) has two auxiliary cards as shown to the right.

The first is the Sync bus controller, which interfaces the external devices to the CPU (discussed below). The second is the VRAM (video random access memory) addresser, which determines the address to be accessed by the video output circuitry (based on the horizontal and vertical timing signals).

If you remove these two auxiliary cards, you will see the single Zilog Z80 CPU (central processing unit) to execute the game logic, graphics, and sound, as well as the ROM (read-only memory) chips that store the game program itself:



Since Ms. Pac-man was originally designed as an enhancement pack for Pac-man, all Ms. Pac-man PCBs are really just Pac-man PCBs with updated ROM chips to store the Ms. Pac-man game code, and an extra auxiliary card. The Ms. Pac-man auxiliary card holds the Z80 CPU and some ROM chips, and connects to the CPU socket on the main PCB using a ribbon cable (the Ms. Pac-man PCBs below are labelled using pink to differentiate them with Pac-man PCBs):

Not all Ms. Pac-man PCBs that you’ll find today have an auxiliary card. This is because the ribbon cable connection can become problematic with age. As a result, you’ll find many Ms. Pac-man PCBs today that have been reconditioned to eliminate the need for the auxiliary card. On these PCBs, you’ll find the CPU in its original socket, and 2 or more ROM sockets added to spare socket ports on the PCB to hold the additional ROM chips (and game program information) needed for Ms. Pac-man:

Bootleg PCBs:


Because of its popularity, there were many bootleg copies of Pac-man and Ms. Pac-man PCBs produced (Ms. Pac-man was bootlegged far more than Pac-man). There was no copy protection on arcade games at the time, and since the arcade game program itself was stored on removable ROM chips on the PCB, anyone who had the right hardware could easily extract the ROM chips and read the game program. Many people did just that - they would take a copy of the game, build a PCB to hold the game that was similar to the original, and make a few small programs to do anything that was stored in a custom chip on the original game PCB. The end result was a bootleg arcade game PCB that was identical (or 99.9% identical) to the original arcade game PCB.

Bootleg PCBs were much cheaper for arcade owners to buy since the people who made the bootleg boards didn’t have any costs associated with creating the game - they just needed to create the custom PCB......which could be done in mere weeks, since most original arcade games also listed the PCB schematics within the manual. Plus, bootleg PCB manufacturers only went after popular selling games like Pac-man and Ms. Pac-man to maximize their profit!

You can easily identify a bootleg Pac-man or Ms. Pac-man PCB by knowing what the original Pac-man and Ms. Pac-man PCBs look like (above). Moreover, bootleg PCBs didn’t have any markings on the PCB that indicated Midway or Namco, and most bootleg PCB manufacturers placed all of the chips on a single PCB for simplicity (no auxiliary card). Although there were several different types of bootleg PCBs created over the years, the most common one used in North America resembles the Ms. Pac-man bootleg PCB shown below:

Since Ms. Pac-man remained popular in arcades long after the 1980s, it was one of the few arcade games from the 1980s that had bootleg copies regularly created well into the 1990s. By 1990, nearly all arcade games followed a wiring standard called JAMMA, so Ms. Pac-man bootleg PCBs made in the 1990s had a JAMMA connector and could be easily fitted into any arcade cabinet of the time. Below is a picture of a JAMMA Ms. Pac-man bootleg PCB:

Re-release Pac-man and Ms. Pac-man PCBs By the late 1990s, it was very clear that two Namco arcade games stood out in popularity compared to the rest: Ms. Pac-man and Galaga. As a result, in 2001, Namco released a Ms. Pac-man/Galaga 20 Year Reunion (Class of 1981) arcade game that contained a small JAMMA standard single board PCB that was colored red. The player could choose to play Ms. Pac-man or Galaga from the screen menu, or enter a secret joystick code at the game start screen to play the original Pac-man (up, up, up, down, down, down, left, right, left, right, left, then wait for the chime and press the Ms. Pac-man start button). The PCB contained a Zilog Z180 CPU (an enhanced Zilog Z80 CPU that runs much faster) to execute the game code. As a result, Namco had to do very little work adapting the original Pac-man, Ms. Pac-man, and Galaga game code for use on this PCB since all three games were originally developed for the Zilog Z80 CPU.

The gameplay of all three games is identical to the original with the exception of a continue game feature that allowed the player to insert another credit and continue from where they left off - a very popular and profitable feature! galaga1pic Needless to say, this arcade game was hugely successful, and led to the hugely successful Pac-man 25th Anniversary arcade machine in 2005 that allowed the player to play the same Pac-man, Ms. Pac-man, or Galaga games, but Pac-man could be chosen from the screen menu. The PCB is nearly identical to the 20 Year Reunion PCB, but has newer and much fewer chips and other components. To celebrate the 30th anniversary of Pac-man in 2010, Namco released yet another arcade game called Pac-man’s Arcade Party, which contained 13 classic Namco games from the 1980s, including Pac-man and Ms. Pac-man. The PCB used in this arcade uses the new JVS standard for connecting to arcade hardware, and essentially has the exact same hardware as the Sony PlayStation 2. As a result, Namco would have spent time to adapt these games to the PlayStation 2 platform.

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