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Pac-Man Prototype Cartridge Explored and Dumped


I bought this “prototype” cartridge a few years back from a seller in California who had a lot of interesting Atari stuff. But is it genuine or is it a modern forgery? Is the game contained within an undiscovered early version? Let’s find out!


Hey everyone, Rees here, and welcome back to ctrl-alt-rees. In this video I’m going to be checking out this prototype Pac-Man cartridge I acquired a few years back, including trying to find out whether it’s actually genuine, as well as seeing if it works, and if so, dumping the code contained within to preserve a potentially important piece of history.

Japanese gaming giant Namco’s iconic 1980 arcade hit Pac-Man is a game that hopefully needs no introduction - but if you do need a bit of a refresher, I recommend you check out my previous video on the subject where I investigated an original Puckman arcade board and how it works and the game’s history in more depth. I’ll link to that at the end of this video and down in the description.

But back on topic, personally, I think the Atari 8-bit home computer port, released in 1982, has to be one of the better contemporary home conversions - certainly miles ahead of what Atari 2600 owners were treated to. But what a lot of people probably don’t know - due to the rarity of the system - is that the Atari 5200 version, also dating from 1982, is even better - running much closer to the original arcade game’s speed, improving the ghost AI, and adding back in all of the nice little extras like the level transition animations which Atari had previously removed to fit the game into 16K.

So what’s the story behind this weird looking cartridge? Well, as you can see, this was once the property of Atari’s prototype lab, part of the software department of their consumer division, which was of course responsible for their home computer and console efforts, as opposed to their arcade division that did… well, I’m sure you can guess.

Developers - in this case Atari programmer James Andreasen - would regularly burn their in-progress games to EPROM - a type of reprogrammable ROM chip - using hardware similar to this Convologic Bytewriter, which incidentally took advantage of the Atari computers’ bidirectional joystick ports for its serial communication.

The burnt EPROM chips were then inserted into an off-the-shelf PCB and cartridge shell to create a prototype cartridge for easy testing on the actual final hardware - in this case, the 5200 console.

Due to EPROMs’ instant turnaround compared to weeks or even months for a full cartridge production run, very limited numbers of the final game were also made in this way to be lent out to game testers and to reviewers before the official release date. Of course, EPROM technology was expensive at the time, and the code held within was very commercially sensitive, so recipients were contractually obliged to return them after use.

Once they’d served their purpose, the EPROMs would be reused by Atari as part of the development process for another upcoming game, which also goes some way to explaining why there aren’t too many of these around these days.

I bought this a fair few years ago now from a specialised dealer in California with close historical links to Atari, so hopefully it is indeed a genuine Atari prototype from back in the day. There are a few modern fakes out there, so I think opening it up and taking a look inside should hopefully give us a better idea of what we’re dealing with.

It’ll also give me the opportunity to take those EPROMs out and dump the code to see whether this is some previously undiscovered early in-development version of the game - which would of course be very exciting indeed - or one of those final review copies, which is still a very cool thing to have.

But I’m getting ahead of myself here - I suppose the first thing we need to know is - does it actually work? And if so, are these any obvious differences with the pack-in version that came with my 2-port 5200? Well, let’s stick it in the slot and find out.

So here it is up and running, which is very cool to see. Now I must confess that I’m not great at Pac-Man at the best of times, and it’s even more of a pain with these non-self-centering analog joysticks, but I did manage to at least get to the first intermission screen to confirm that it’s there. The game certainly runs and feels identical to the final version that I have, and the only other known prototype is a very interesting looking kiosk demo, so it’s looking likely that I haven’t stumbled across any pre-release code here.

In fact it even has the same easter egg as the retail version - entering “0722626” on the title screen shows the developer’s name. These easter eggs were famously frowned upon by Atari’s management and so were often added very late on in development in an attempt to “fly under the radar”, so to speak.

So we know that it works - but I think it’s about time I took this apart to see what it looks like inside.

Removing the casing is relatively straightforward on these 5200 cartridges, with just a single screw to remove on the back (which incidentally is missing from this cart), and then applying pressure to the sides of the front half of the cartridge shell to disengage the plastic clips.

Of course these clips are old and brittle by this point, so it’s pretty nerve wracking, especially on a rare cartridge like this, but thankfully it pops open without a hitch.

So what’s inside? Well, it certainly looks period authentic, with 3 Intel D2732A EPROMs dated 1979: of course these would have been reused many times for various different development projects and were probably previously used for testing Atari 2600 or 8-bit home computer software.

These are mounted on a distinctly late ‘70s - early ‘80s looking PCB with a copyright date of 1981 so with this, the general patina of the cartridge and the label, and the place I bought it from, I’m very happy with its provenance.

These chips may look soldered, but they’re actually easily removeable. I presume they couldn’t use standard sockets because they didn’t have enough room inside the cartridge for the added height, so these soldered sockets are a very clever solution that I hadn’t come across before.

So, the moment of truth, and my chance to potentially do something important for the world of software preservation. As we can see, the ROM image is split across 3 8K EPROMs, and extracting a dump of the game just involves inserting them one at a time into my USB EPROM burner, selecting the correct type of chip from the list, and dumping the contents of each to a file.

I then concatenated the 3 files together, and used a tool called Hex Fiend - great name by the way - to compare the dump to the commercial release that I downloaded from

Well, as you can see, apart from some padding at the beginning of the file which I assume is required for some emulator or other to be able to use it, the contents are indeed identical. So it looks like what we have here is one of those QA or review copies of the final game. Still a very exciting thing to own, especially in this condition and in full working order. At least, I hope it still is when I’ve put it all back together.

…and as you can see, it survived the reassembly process unscathed and is still working great, which is always a bonus when you’re dealing with a piece of history like this.

And I certainly don’t think it was unreasonable to expect to stumble across some early and interesting prototype - after all, this is how unfinished builds of games are discovered and preserved, but it seems like it just wasn’t meant to be on this occasion, and of course that’s perfectly fine and hopefully you found the whole process as fascinating as I did.

Big thanks as always to my patrons and channel members whose names you can see up on the screen, and indeed to everyone who watches, shares, likes and subscribes and motivates me to keep doing what I’m doing.

Don’t forget to check out that previous video all about the history of Pac-Man where I check out an original Japanese Puckman arcade board - links to that will be at the end and down in the description - and finally all that’s left is to thank you very much for joining me, and I’ll hopefully see you again next time.

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Relevant Links:
My Previous “Puckman: History Video:
Bytewriter Image Credit:
5200 Prototype Cartridge Image Credit:
Stock Atari Development Footage:

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