As mentioned before, the NES and other games consoles as well as several DVD players use some sort of a region coding system. These systems could need to be listed for what is region locked or not.
Most early, cartridge based systems mainly used chips to prevent game from a different region from playing, but some others just used different cartridge shapes or connection pin sets (how the console communicates with or reads the cartridge). The earlier consoles, generations three through five, that were region locked were NES, Sega Master System, Super NES, and Playstation. Also among consoles from these generations, there were some with some form of lockout, but weren’t regionally locked to a degree. The Nintendo 64 used a lockout chip like the 10NES but only to play approved games and not for region codes. The Sega Saturn did use region codes, but most copies of games were playable on consoles from multiple regions.
The recent two generations are where regional lockout is most present. Of generation five, all of them are region locked: Sega Dreamcast, Nintendo Gamecube, Playstation 2, and Xbox. The latest, seventh, generation of console is slightly more lenient on region codes. The Nintendo Wii is completely region locked. The Xbox 360 is locked, but much of its game library isn’t restricted and playable in multiple regions. The Playstation 3 isn’t itself region locked, but backwards compatible models are locked for PS2 games. Four of these, Playstation 2, Playstation 3, Xbox, and Xbox 360, also play DVDs, so those are also locked by DVD regions (mentioned later).
Most handheld consoles, such as the various Game Boys and the Game Gear, weren’t region locked, but more recently newer systems are being locked. The Nintendo DS wasn’t originally locked, but the Nintendo DSi, DS games released after it, and the Nintendo 3DS are locked. The Playstation Portable is region locked but only for movies played on its Universal Media Disks (UMD) as according to DVD regions. When the Playstation Vita comes out, it will be region free and no longer supports UMDs.
The recent consoles and their games are released among 4 regions: Japan and Asia (NTSC-J), North America (NTSC U/C), Europe and Oceania (PAL, PAL/E), and China (NTSC-C).