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Happy 30th anniversary, Tengen! Your anti-DRM NES chip fought the law, and the law won

Atari offshoot tried to take down Nintendo cartridge racket

By Shaun Nichols, 25 Jul 2015

In 1985, Japanese giant Namco got out its wallet, and bought control of Atari Games – the coin-op arcade games maker that was doing rather well compared to its ailing home console cousin, Atari Corp.

The deal was the first step toward a massive legal battle that changed the way console manufacturers produced, licensed, and distributed their games. And this is how it happened:

A year later, in 1986, Atari Games staff bought Namco's stake in the biz, and decided they fancied their chances in the rocky world in home console gaming. So they formed a division called Tengen to produce games for the classic Nintendo Entertainment System (the NES). Like Atari, Tengen was named after parts of the ancient game Go.

What followed was a prolonged legal battle with Nintendo that included reverse-engineering, intellectual property rights, allegations of piracy, and an antitrust challenge.

In the meantime, some of the most iconic games of the late 1980s were released, both with and without Nintendo's approval.

Tengen RBI Baseball

Tengen's RBI Baseball ... Believe it or not, in 1988, this was years ahead of its time

Nintendo maintained a tight grip on the NES games market: Ninty limited the number of games a company could produce every year, insisted on approving every title before it was sold to gamers (and would reject anything it didn't like). Nintendo also forced publishers to buy cartridges equipped with a custom anti-piracy chip available only from Nintendo.

If that chip wasn't present in a cartridge, the game wouldn't start – so publishers had to dance to Nintendo's tune, and pay up to use its official licensed cartridges, or their products wouldn't work.

Tengen tried to negotiate with Nintendo on the licensing terms, but didn't get very far, so in 1987, Tengen relented and signed on the dotted line: it could only produce five games a year, and for two years its titles had to be exclusive to the NES. The following year, Tengen made three licensed games (its only licensed NES games): Pac-Man, Gauntlet and RBI Baseball.

Behold, the king of the late 80s

Nintendo's obsessive controls over games were born of the games crash in the early 1980s, when a flood of cheap home consoles and even cheaper, crappy games diluted the market and nearly wiped out console gaming. Nintendo didn't want to let any old garbage appear on its system.

"It was definitely a good idea at the time because you don't want a flood of games coming out for your console, a lot of them bad," Norman Caruso, creator of The Gaming Historian website, told The Register.

Nintendo, not wanting a repeat of the crash, kept its developers in a walled garden where they could only produce games when Nintendo allowed them to, with cartridges Nintendo supplied. The issue came to a head for Tengen and other developers when, in 1988, a chip shortage further limited the ability of developers to put out new NES games.

"Companies were under a stranglehold from Nintendo," Caruso said. "I think companies felt they were having Nintendo control their profits."

According to games collector and historian Pat "The NES Punk" Contri, there was one very big reason for the split between Tengen and Nintendo: Tetris.

In the late 1980s, Nintendo and Tengen's Atari parent battled over which company had the rights to produce Tetris cartridges for the NES. Both Atari and Nintendo claimed to have purchased the rights to Tetris. Nintendo went on to win the case, and make its version of Tetris the only one officially available for the NES.

"It had everything to do with Tetris," said Contri. "That caused a rift, and Nintendo pulled the publishing rights from Atari."

Tengen's Tetris

Behold, the game that launched a cartridge war

It was around this time that Tengen undertook perhaps its most audacious move. The company tried to reverse-engineer Nintendo's anti-piracy cartridge chip – the 10NES lockout chip, aka the Checking Integrated Circuit (CIC). This was a forefather to today's so-called digital-rights management mechanisms, or DRM, which try to stop people copying and sharing copyrighted games, files, music, videos, and so on.

If Tengen could produce a replica of the 10NES, and stick them in its own cartridges, the developer could churn out as many working copies of games as it liked, and Nintendo wouldn't be able to stop it.

The lockout chip is really two identical chips: one in the game cartridge and one in the console. When the NES is powered up, and the two chips are connected through the cartridge slot, they exchange data between themselves; if the wrong bytes are received from the cartridge in response to what's sent from the console, the lockout chip in the NES forces an immediate reboot loop: it pulls the 6502 CPU's reset line low, which keeps the system from doing anything.

If you produce an unlicensed game – or simply copy or pirate a game – you won't have the lockout chips from Nintendo, and without those, the NES will reboot over and over when your title is inserted, rendering it useless. Some makers of unlicensed games had a piggyback slot in their cartridges into which a licensed title had to be fitted by the player; this passed the 10NES signals between the console and the legit cartridge so the unlicensed game could be played, but it was an embarrassing kludge.

Inside the 10NES aka the CIC

It turns out it was actually really difficult to work out the protocol between the chips; they were never deterministic, and people just couldn't work out the right responses to the console's challenges. The 10NES was a primitive 4-bit microprocessor that ran software in 512 bytes of ROM, using 16 bytes of RAM, and a four-entry stack.

Back then, Tengen decided it would need a copy of the microcontroller's source code and blueprints to crack this tiny beast.

To do this, Tengen lawyers pulled a fast one on the US Copyright Office by falsely claiming that they were locked in a copyright dispute with Nintendo. The legal eagles were able to not only view, but make copies of the secret 10NES documentation.

With that information in hand, Tengen was able to build cartridges that could send the right signals to the NES and defeat its anti-piracy protections. Tengen took action against Nintendo in December of 1988, launching its line of lockout-foiling game cartridges in a distinctive black casing.

But what about the Tengen games themselves? Were they, in fact, decent titles or just oddities in strange cases?

Contri said that, indeed, many of the Tengen titles were solid games, ports of successful Namco titles like Pac-Man, the influential RBI Baseball (the first console title to be licensed for the real names and stats of Major League players), and Gauntlet. All three games were first sold as grey Nintendo-approved cartridges, then later released as Tengen cartridges.

Along with releasing its own cartridges, Tengen filed suit against Nintendo alleging antitrust violations. Nintendo counter-sued Tengen for its unauthorized games cartridges.

Tengen's Pac Man

Including a little-known puzzle game called "Pac Man"

By 1990 a court also granted Nintendo the right to go after any retailer who sold the unlicensed Tengen games, and by 1992, Nintendo ultimately prevailed in the case to bar Tengen's unapproved games permanently.

Tengen gave up the game and went on to focus its efforts on the Sega Genesis, where titles such as After Burner would catch on with Sega's next-gen console. The company was eventually absorbed by Time-Warner Interactive and in 1994 Tengen was defunct.

Nintendo, of course, would continue its success in the console market throughout the 1990s and into the 21st century, but not before making some major changes in the way it did business with developers.

The case also showed that, yes, the home console market had fully recovered from the mid-80s gaming crash, and then some. Tengen showed that not only was there a demand from the public for more games, but there were also talented development houses willing to break all the rules to get games out to the public.

"This was one of the first big cases where a licensee was challenging Nintendo, and it had a snowball effect," Caruso said.

"Atari sued Nintendo for the same thing, the FTC investigated Nintendo, [and] it really caused Nintendo to ease their licensing restrictions."

The ruling also impacted the IT space as a whole in one very important way. Over the course of the copyright hearing, the court ruled that reverse engineering was protected. This paved the way for everyone from modding enthusiasts to security researchers to use reverse engineering as a tactic for better understanding how applications operate.

Tengen may have had a brief stay in the console market, particularly in regards to the NES, but the company definitely left its mark before it went out. ®

For a detailed study on the Tengen/Nintendo story, check out The Gaming Historian documentary on YouTube. Thanks to both Caruso and Contri.

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