Why Does the NES Turn On and Off When a Game Doesn’t Work?

We’ve all been there when it comes time to play a game on our NES.  You pull the game off your shelf, maybe shake it a bit to loosen the dust.  I’ll always go with the proactive blowout next because you just know it will come to that eventually.  Even better, add in a vibrating taunt while you do it.  I like to yell WORK WORK WORK into the bottom of the cart, personally.  It shakes the circuitry up.  You know it works…

Push the game in.  Press the cartridge down.  Brace yourself as you hit the power button and…

…it’s on…it’s off…it’s on…it’s off…blink…blink…blink…blink…

Why Does It Blink?

The short answer to this question is that the game’s circuitboard isn’t making proper contact with the circuitry inside the NES. There’s either dust or grime on either of them or things aren’t lining up quite right. A great tip is to “rotate” the game a little bit while in the down position in the NES and then resetting.  However, if the cartridge is dirty, you’re going to have it clean it first with either Isopropyl, rubbing alcohol or Deoxit.

Yet…that’s not exactly why the NES blinks on and off like that.

In actuality, the NES runs through this blink-every-second routine because of a special lockout chip inside the system that’s not convinced you’re using a licensed cartridge.  You see, back in the old days of video games, any old company could release a game for any console they wanted.  Many of these were awful.

Remember the Atari 2600?  What a great system!  Maybe you grew up on it.  Do you recall all your favorite games?  Pitfall, Combat, Adventure, Boxing, Warlords…oh man, classics!  Did you have any friends who had an Atari?  They had many of the same games. Gosh, it was so long ago and everyone remembers the same games, surely Atari didn’t make many games for it. How many Atari games in total were there do you think?  50, 75..?  Well, there were about 125.  Sounds about right, but that’s not how many total games there were.  Would you believe that, thanks to 3rd-party companies, there were actually over 600 games for the Atari 2600?!

That’s right.  And 2/3’rds of them were easily horrible, unplayable games. Don’t get me wrong, some were fantastic, too.  In fact, Pitfall may be the most popular and beloved game on the system — but believe it or not it was never licensed by Atari! Sadly, there were too often terrible games like Birthday Mania, Fire Fighter, and even Bugs that were published solely to try to make a quick buck.  These weren’t game made by qualified designers either. They were simply made to try and make a quick buck off unsuspecting customers.

What Did Nintendo Do To Prevent This?

Nintendo knew this was a problem and it’d helped kill the video game market for a few years, but how could they avoid the same fate?  It’s really hard to stop other companies from reverse engineering your hardware and making their own games if they can make a lot of money doing it. So, they created a lockout chip as a sort of trap.


A version of the 10-NES you’ll find on any NES motherboard in various forms.

The lockout chip, sometimes referred to as the 10-NES chip, sat on the motherboard and required a similar chip on each NES cartridge to exist in order to operate with it.  When you power on an NES, the chip asks the cartridge for a specific response.  The boring details of the AUTH and ACK are beyond the scope of this humble little article, but suffice to say that a licensed cartridge will answer correctly.

When it’s inserted correctly anyway.

You see, that’s why the NES blinks.  It’s actually the lockout chip telling the NES, “Hey, I don’t think this cartridge is legit!”  The NES then initiates a reset on itself similar to if you’d pressed the button yourself.  This happens every second until the NES gets the response it expects.

Now, 99% of the time, the NES is resetting because the cartridge isn’t inserted correctly or needs a good cleaning.  However, the chip is really there to make it difficult for 3rd-party companies to create unlicensed games for the system.

Right about now you’re asking, “But…but…wouldn’t it be easy to reverse engineer the lockout chip, too?”  Why yes!  Companies did do that!  Most famously Tengen did, but that’s the sting to the tail for the 10-NES…to replicate the chip on a cartridge meant to violate US Patent 4,799,635!  When Tengen did this, Nintendo sued the bejesus out of them and won easily.  It doesn’t make much sense to create unlicensed games if Nintendo is going to be awarded all of your profits now is it?

(Oh, and fun fact, did you know that Tengen was actually Atari?  Yup.)

Is There a Way Around The Lockout Chip?

The short answer is yes.  There’s many resources online that tell you how to do it. (TL;DR cut one of the chip’s leads.)  In fact, some 3rd-parties included a piece of paper explaining how to do it if you had troubles getting their game working.  Obviously, that’s not a solution for the mass market so manufacturers attempted to bypass the chip by means other than reverse engineering with some having great success.  Unfortunately, over time Nintendo would modify their lockout chip to retroactively shut down previously successful attempts so if you have a late-model NES you likely can’t get many unlicensed games working.  Tengen games will work, but boy it cost them a lot of money!

My suggestion?  Leave the lockout chip alone.  Most of the time, your game wasn’t going to work whether it was enabled or not. Clean your games and clean your NES and you’ll get them to work.  If you want all your unlicensed games to work, will then feel free.  Just be careful you don’t frag your system.  They aren’t making any more of them!

Follow us on Twitter @JinjaBobot or Find Us on Facebook to get updates on new articles, contests, collectors’ finds and more!

About John Blanco

John Blanco is an avid game collector and loves to write about his hobby as much as he participates in it. He run the Denver Retro Gamers Facebook group in Denver, Colorado, and coordinates swap-style meetups with dozens of other collectors every couple of months.

Leave a Reply

Your email address will not be published. Required fields are marked *