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Intellivision System Changer

In 1982, Coleco dropped a bomb on the game console industry. Atari led the industry in sales, with Mattel, the toy maker, taking the number two spot with a slightly more advanced console called the Intellivision that enjoyed reasonable if modest success. Then Coleco came along with its own high-end console. One of Coleco’s gimmicks was an expansion module to make its console compatible with the Atari console, immediately making it have more cartridges than anyone else. Mattel decided to counter.

The Mattel System Changer was essentially the equivalent of the Coleco Expansion Module 1, just for a different console. The function is the same, but the outcome was a bit different.

No lawsuit

Mattel System Changer

The Mattel System Changer allowed Mattel to one up Coleco in 1983, at least momentarily.

Atari famously sued Coleco for patent infringement over the Expansion Module 1. One of the enduring myths of gaming history is that Coleco won. Coleco won an injunction, but the two companies ended up settling, with Coleco agreeing to pay royalties on the two patents Atari said they infringed upon.

There were only three major computer chips in an Atari 2600. Two of them, the CPU and multifunction I/O chip, were standard off the shelf parts available from numerous suppliers. The third was a custom chip called the Television Interface Adapter. That chip was covered by patents.

Coleco had a commissioned a clone of the chip from VLSI, a chipmaker in Taiwan.

While I don’t know for certain that Mattel bought their chip from VLSI, Mattel and Coleco were VLSI’s two biggest customers in the 1982 and 1983 time frame. The Intellivision’s chipset came from another company, General Instruments. So there wasn’t much else Mattel could have been buying from VLSI.

Why Atari didn’t sue Mattel

The question, therefore, is why Atari didn’t sue Mattel. There are several possibilities.

The first is that you couldn’t tell what was in the System Changer by opening it. Usually when you buy a consumer electronics product, it will have a circuit board inside with a number of chips on the board in plastic packaging with part numbers and date codes on them.

But sometimes you don’t see the chips in traditional packaging. When a manufacturer needs to skimp every penny, or wants to be secretive, they skip the packaging. They just buy the chip wafers, solder the wafers on to the board, and then cover the chips and the connections with blobs of epoxy. That’s what Mattel did.

It means you can’t repair the device, but it also makes it extremely difficult for anyone else to reverse engineer it.

It is possible that Atari decided it wasn’t worth the effort.

Some have speculated that Mattel got in on the same deal that Atari gave Coleco, with Mattel, or possibly VLSI, paying Atari a royalty on each unit sold.

A third factor is that by the time this was happening, Atari was also a VLSI customer. Atari was trying to build 2600 compatibility into its 7800 console. The problem was even though Atari had the patents, their chip designer was long gone. Jay Miner had left Atari to go develop pacemakers, and then he joined some secret company called Amiga.

Since VLSI had dug into the TIA chip, which Atari knew about because of the court battle with Coleco, Atari sought VLSI’s help building the new Maria chip that went into the 7800.

One or more of these factors, potentially all three, played into Atari never suing Mattel.


Conceptually, The Mattel and Coleco devices worked the same way. They incorporated all of the components of an Atari 2600 in a small plug-in module that basically ended up using the host console as a power supply and a video output. The Atari controllers and cartridges plugged into the expansion unit. Since the systems didn’t have any hardware in common, and the Mattel system wasn’t nearly powerful enough to emulate any of the Atari hardware, both expansion modules were simply bolting two consoles together.


But there were also some differences. The Mattel module was not a commercial success. The Coleco module is common enough today that it generally is considered a success.

The first problem was that the System Changer was designed for the Intellivision 2, which was mostly the same hardware with updated styling. But not completely the same. Use with the original version required a modification to the motherboard. That meant having your console professionally serviced so you could use what was supposed to be a plug-in module.

The second problem was that after you resolved the compatibility issue, the combination looked awkward. The color scheme was all wrong, and the lines were all wrong. It looked like an afterthought. Which it probably was.

And by the time the System Changer hit the market, the crash of 1983 was pretty much underway.

There is a perception that everyone lost interest in video games in the middle of 1983 and put their Ataris in the closet. It wasn’t nearly as coordinated as that. It was more like demand and sales tailing off. The whole industry was used to sales doubling every year, and when sales didn’t double in 1983, everyone panicked. This had a snowball effect. Atari cut prices, retailers cut prices, and it didn’t have the desired result.

One of the side effects was that Atari started producing native versions of its most popular titles for other consoles, including Intelevision. So it didn’t make much sense to buy the expansion unit and Atari joysticks just to play Pac-Man or Pole Position. You could buy better versions of Pac-Man and Pole Position for the Intellivision console itself and save money.

And if you found the bargain bin 2600 cartridges at the front of KB Toy and Hobby compelling, it was cheaper to just buy an Atari console or the Coleco Gemini knockoff to play them.

Mattel quickly discontinued the System Changer, and for that matter, they didn’t stay in the video game business much longer.

So that’s why the Mattel System Changer is rare today and more of a curiosity than anything.


It also turns out it wasn’t 100% compatible. In some cases, the compatibility issues were physical. Subtle differences in the cartridge slot design meant that there were exactly 39 third-party titles that just didn’t fit correctly. But a smaller number of the games didn’t work right even after fixing the fit and finish problems. Since both the Mattel and Coleco expansion modules have the same compatibility issue, I think it’s because of the TIA clone they used. VLSI made the clone by slicing the Atari design into quadrants and then shuffling them, then rerouting any electrical connections they suffered by moving the quadrants. Anytime you do something like this, you run the risk of minor timing issues. They would have accounted for this in the design as best they could, but a handful of titles, mostly from the publisher Tigervision, didn’t work quite right.

Don’t get me wrong, we are talking 99.9% compatibility here, if not a bit higher than that even. And the biggest name titles all worked. But it’s not quite 100% compatible.

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