View source for Mega Drive region coding

[[File:NTSCJ Only MD.png|thumb|right|320px|A common region lock screen denoting a game designed only for NTSC-J Mega Drive systems.]]
<section begin=intro />More than any other [[Sega]] system, the [[Sega Mega Drive]] is affected by differing forms of '''region coding''', implemented so that games were optimised for (or locked out of) three main marketing regions; NTSC-J (Japan and parts of Asia), NTSC-U (North America) and PAL (Europe and Australia).

Like the [[Sega Master System]] and rival console the [[Nintendo Entertainment System]], Japanese cartridges are a different physical shape to their Western counterparts, meaning Japanese games could not be played on American systems or vice versa without some sort of adapter (or by disassambling cartridges or consoles). However, Mega Drive hardware is also configured to be one of the three aforementioned regions, meaning software could adjust itself depending on what sort of Mega Drive system is detected.

The latter is not an unusual practice (and indeed similar methods were employed for many consoles going forward), however unlike more modern systems, software was under no obligation to adapt to the detected region, meaning only part of the Mega Drive's game library takes note of what type of system is in use.<section end=intro />

The following details games which are known to have issues running in certain regions:

==Region locked games==
These games are designed so that they will not run at all on certain consoles. Usually a message is displayed informing the user that the game cannot be played. The Japanese version of [[Namco]]'s ''[[Rolling Thunder 2]]'' was reportedly the first Mega Drive game to be region locked{{magref|segapro|3|67}}.
===NTSC-J consoles===
{{multicol|
{{#cargo_query:
table=regioncoding
|fields=name,rom
|where=ntscj="locked"
|orderby=name
|format=template
|template=RegionCodeDisplay
|limit=800
}}
|cols=4}}

===NTSC-U consoles===
{{multicol|
{{#cargo_query:
table=regioncoding
|fields=name,rom
|where=ntscu="locked"
|orderby=name
|format=template
|template=RegionCodeDisplay
|limit=800
}}
|cols=4}}

===PAL consoles===
{{multicol|
{{#cargo_query:
table=regioncoding
|fields=name,rom
|where=pal="locked"
|orderby=name
|format=template
|template=RegionCodeDisplay
|limit=800
}}
|cols=4}}

==Games which display a blank screen==
While we can assume these games are also region locked (given that they refuse to boot in certain regions), nothing of value is displayed on-screen, which could suggest the game has not been programmed to handle the incorrect regions.
===NTSC-J consoles===
{{multicol|
{{#cargo_query:
table=regioncoding
|fields=name,rom
|where=ntscj="blank"
|orderby=name
|format=template
|template=RegionCodeDisplay
|limit=800
}}
|cols=4}}

===NTSC-U consoles===
{{multicol|
{{#cargo_query:
table=regioncoding
|fields=name,rom
|where=ntscu="blank"
|orderby=name
|format=template
|template=RegionCodeDisplay
|limit=800
}}
|cols=4}}

===PAL consoles===
{{multicol|
{{#cargo_query:
table=regioncoding
|fields=name,rom
|where=pal="blank"
|orderby=name
|format=template
|template=RegionCodeDisplay
|limit=800
}}
|cols=4}}

==Games which break==
In certain circumstances, games will attempt to run in the wrong region, only to break further down the line.
===NTSC-J consoles===
{{multicol|
{{#cargo_query:
table=regioncoding
|fields=name,rom
|where=ntscj="broken"
|orderby=name
|format=template
|template=RegionCodeDisplay
|limit=800
}}
|cols=4}}

===NTSC-U consoles===
{{multicol|
{{#cargo_query:
table=regioncoding
|fields=name,rom
|where=ntscu="broken"
|orderby=name
|format=template
|template=RegionCodeDisplay
|limit=800
}}
|cols=4}}

===PAL consoles===
{{multicol|
{{#cargo_query:
table=regioncoding
|fields=name,rom
|where=pal="broken"
|orderby=name
|format=template
|template=RegionCodeDisplay
|limit=800
}}
|cols=4}}

==Unoptimised games==
PAL and NTSC systems run at different speeds and can support different screen resolutions. In some cases, no effort is made to optimise for each system, leading PAL games to run too slow (with borders), or NTSC games to run too fast (or have visual elements drawn off-screen).

Many PAL titles, particularly earlier prints, are notorious for running noticably slower than their NTSC counterparts, leading many to import or modify their consoles to fix the speed issue. Unoptimised NTSC games are far rarer, and usually consist of European-developed games not being adjusted correctly.

===NTSC-J consoles===
{{multicol|
{{#cargo_query:
table=regioncoding
|fields=name,rom
|where=ntscj="unoptimised"
|orderby=name
|format=template
|template=RegionCodeDisplay
|limit=800
}}
|cols=4}}

===NTSC-U consoles===
{{multicol|
{{#cargo_query:
table=regioncoding
|fields=name,rom
|where=ntscu="unoptimised"
|orderby=name
|format=template
|template=RegionCodeDisplay
|limit=800
}}
|cols=4}}

===PAL consoles===
{{multicol|
{{#cargo_query:
table=regioncoding
|fields=name,rom
|where=pal="unoptimised"
|orderby=name
|format=template
|template=RegionCodeDisplay
|limit=800
}}
|cols=4}}

==Partially-optimised games==
By 1992 efforts were being made on behalf of developers to ensure that games were at least partially optimised for PAL systems. While optimisations vary, usually this involved speeding up the music, as opposed to speeding up the game logic.

===NTSC-J consoles===
{{multicol|
{{#cargo_query:
table=regioncoding
|fields=name,rom
|where=ntscj="partial"
|orderby=name
|format=template
|template=RegionCodeDisplay
|limit=800
}}
|cols=4}}

===NTSC-U consoles===
{{multicol|
{{#cargo_query:
table=regioncoding
|fields=name,rom
|where=ntscu="partial"
|orderby=name
|format=template
|template=RegionCodeDisplay
|limit=800
}}
|cols=4}}

===PAL consoles===
{{multicol|
{{#cargo_query:
table=regioncoding
|fields=name,rom
|where=pal="partial"
|orderby=name
|format=template
|template=RegionCodeDisplay
|limit=800
}}
|cols=4}}

==References==
<references />

[[Category:Mega Drive games| ]]
[[Category:Region coding| ]]