I first came across it when my cousin had it. I was still buying game roms at that time, and I saw that she didn't. She just had to download them from the internet. So I bought one for myself. The R4 Chip (Revolution for DS) was supposed to be a storage system for the DS. The device is legal, but people download games from the internet which IS illegal. Since downloading games is free, and the chip only costs around 400 dollars HKD. Which is the same price as buying ONE game rom, many people are downloading the games on their R4 instead of buying the real thing. This obviously is a let down for the company Nintendo. Less people will start buying their games, they would rather buy an R4 and download games from the internet.

The R4 has the ability to have a cheat option, which lets you have many power up codes, infinite life, infinite money, max HP, max time, etc. for your game. Not every game has the cheat option, but I found this very useful since I suck at playing games. You also get to download songs and store it on your DS. Or even put movie clips in it. And games are often available on the internet before the games are even officially released in stores. So not only is it cheap, but it also has a bonus to the original game rom. ALTHOUGH, the bad thing is that the games sometimes freezes at times. Not very much. Like once in a few weeks? Maybe it's just me.

Some people say that the R4 effects your game system. But it does not. It simply skips the selection screen. It does not damage your DS in any way. You can still play the original game ROMS if you take the chip out.