Sega Mega Drive cartridges are the primary storage medium for the Sega Mega Drive.
The Mega Drive runs games housed in plastic cartridges uniquely shaped to fit the system. Though the technology exists within the console to run Sega Master System games, the Power Base Converter is required to convert between the differing pin connections and slot sizes.
Official Mega Drive cartridges are smaller than their Master System/Mark III counterparts, with rounded edges and bigger labels layered over the top and front of the cartridge.
As with the Master System, Sega-manufactured Japanese, Korean and Asian cartridges are shaped differently to those seen in North America, South America, Europe and Oceania, however the differences largely concern the aesthetics - "Eastern" Japanese-style cartridges opting for a more rounded approach with ridges, while "Western" cartridges being more angular and simplistic. Unlike the Master System, the Mega Drive has end-labels for easier reading and storage in Western regions.
Pin layout is the same between the two types, however the base of the cartridge determines whether it can be safely inserted into the system - two extra pieces of plastic prevent Japanese cartridges from being inserted in western systems - these can be removed with modification, or as mentioned above, circumvented with adapters. This extra plastic is not present in systems such as the Genesis 3 and Sega 32X, nor does it exist in Japanese Mega Drives.
One interesting feature of Japanese cartridges is a inclusion of a cartridge "lock", which prevents the cartridge from being removed when the system turns on. A plastic piece from the system is slid across to a gap on the left hand side of a Japanese cartridge, securing it in place when the power switch is moved (similar tricks can be found on the Super NES and the TurboGrafx-16). This locking mechanism is only present in Japanese Model 1 Mega Drives and is absent in all western models - the vast majority of Western cartridges lack the gap required for cartridge locking, with exceptions being the likes of "special" cartridges, e.g. Sonic & Knuckles.
The lack of cartridge lock can be exploited, for example, to gain access to the level selection screen in Sonic 3D Blast.
Cartridge designs for Altered Beast - though labels would change dramatically over the console's run, the physical shape would remain consistent.
Sonic & Knuckles famously introduced so-called "lock-on" technology to the Mega Drive library, in which a second cartridge could be stacked on top to create a new game. While there were rumours of other lock-on games in development, Sonic & Knuckles is the only example which made it to market.
While the vast majority of games will communicate with Sonic & Knuckles, the end result will be a randomised variant of Blue Sphere. To access Blue Sphere in full, Sonic the Hedgehog must be "locked-on", and Knuckles the Echidna in Sonic the Hedgehog 2 and Sonic the Hedgehog 3 & Knuckles can be accessed by locking on Sonic the Hedgehog 2 and Sonic the Hedgehog 3, respectively.
If a cartridge with a more than 2MB of storage is locked on to the cartridge, Blue Sphere will not load, and the setup will revert to the standard Sonic & Knuckles game. This is due to a quirk in how the game reads data from its locked-on segment - rather than reading from the first 2MB of the locked-on ROM, it will read from the last 2MB and subsequently not detect a correct header. Sonic Classics is the only exception to this rule - a compilation seemingly designed so that data from the original Sonic the Hedgehog would be detected in the right place for Blue Sphere to load.
While Sonic the Hedgehog 3 is a region-locked game, Sonic & Knuckles is not, nor does it care what region Sonic 3 is from. As such, the subsequent creation of Sonic the Hedgehog 3 & Knuckles will also be region free.
Created by Codemasters, J-Carts break the norm by including two extra joystick ports built into the cartridge. This permitted four-way gameplay without a multitap adapter. Only six J-Carts were released: Pete Sampras Tennis, Pete Sampras Tennis 96, Micro Machines 2, Micro Machines 96, Micro Machines Military Edition, and Super Skidmarks. Several were also released as standard cartridges.
Virtua Racing contains a custom-designed DSP chip, known officially as SVP, or Sega Virtua Processor. It allows for enhanced graphics and sound capabilities. This chip essentially serves as an extra processor, allowing the game to produce a significantly higher number of polygons than would be possible on a standard Mega Drive. It was also significantly more powerful than the Super Nintendo's Super FX chip. However, Virtua Racing released with a more expensive retail price.
The SVP chip was revealed for the Mega Drive in Summer 1993, before the Mega Drive version of Virtua Racing released in 1994. Interestingly, Virtua Racing was the first to showcase the power of the SVP chip - plans were underway to produce more games using this chip, using a "Modular Converter" cartridge to cut production costs. This converter would contain the SVP chip, with the enhanced game designed to use the SVP chip plugging into the top of the unit. However, due to the costs of production against the Mega Drive/Genesis' age and falling popularity, the project was dropped. Virtua Racing also has a cartridge roughly one-and-a-half times the size of a usual Mega Drive cartridge due to the added chip, and is incompatible with the Sega 32X add-on.
The SVP chip adds the following capabilities to the Mega Drive hardware.
The majority of home consoles usually see the platform holder choose to either apply strict region encoding to their systems, or to avoid the practise altogether. The Mega Drive is different in that some games are region locked, while others are region free.
In an attempt to control Mega Drive content, Sega invented the TradeMark Security System (TMSS), officially documented as early as 1989 but not truly enforced until late 1992. TMSS was designed to stop Japanese software from running on Western "export" consoles, although was not implemented in any console produced prior to 1991, and became more of an anti-piracy measure than a means of region locking.
As most Japanese games cannot physically fit in a Western system (or vice versa), this was perhaps presumed sufficient in the early days of the system's lifespan. However some Mega Drive variants will accept both Western and Japanese games without modifications, so those serious about region encoding were forced to implement it in software. Support for the feature is mixed - some publishers such as Konami usually implemented region locking in full, while others such as Electronic Arts usually ignored it altogether. The Japanese version of Namco's Rolling Thunder 2 was reportedly the first Mega Drive game to be region locked.
Whether a message is displayed was also up to the developer. The majority of region locked games state which type of Mega Drive is needed, however some publishers such as Virgin Interactive are more vague, and Konami games simply display the Konami logo. Others such as Zoop show only a blank screen.
Other games will adapt to the hardware detected. For example, if Sonic the Hedgehog 2 detects a Japanese machine, all instances of "TAILS" will be replaced with "MILES".
Virtually all games produced prior to 1993 (as do many made since) will run on any console. The following lists games known to have compatibility issues when played in the "wrong" region (although in rare cases, Game Genie or Action Replay codes can alleviate some of the problems).
Mega Drive consoles sold officially in PAL regions are adapted to the differing video standard. PAL offers a 50Hz screen refresh rate but the possibility of a higher resolution 320x240 display, while NTSC refreshes at 60Hz and typically offers a maximum resolution of 320x224 (exceptions include games which make use of the "interlaced" screen mode - Sonic the Hedgehog 2 and Combat Cars).
If a game designed for an NTSC unit is run on a PAL machine, the difference in refresh rate means the game will run 17.5% slower and will have extra horizontal borders surrounding the top and bottom of the image. Knowing this, some developers (particularly those based in Europe) chose to optimise their games for PAL regions, typically by speeding up the music and gameplay. On rare cases this also meant utilising the extra 16 rows of pixels.
Unlike newer consoles such as the Sega Dreamcast, the Mega Drive does not natively support any PAL60 modes. It is not, however, uncommon to see modified hardware to circumvent these issues.
Though rare, some NTSC Mega Drive games, typically those which originated in Europe, were not optimised for the hardware and so run faster than they should:
The Mega Drive can only address up to 4MB of game at any one time, meaning under normal circumstances, Mega Drive games are limited to a maximum size of 4MB (or 32 megabits as was more commonly advertised). This is increased, however, using a technique known as bank switching - hardware built into the cartridge which allows "banks" of memory to be "switched" at run time. As an example, the first half of a game might be loaded into memory when the console is turned on, and when a certain condition is met, the second half is loaded in, replacing the first half (how this is achieved depends on how the game is programmed).
Bank switching in dedicated video game consoles dates back to at least the Atari 2600, however it was not implemented in Mega Drive titles until the mid-1990s, as for the most part, cartridge space was not considered an issue for developers (or at least, not enough of one to justify the extra cost implementing a bankswitching system, and for many years the Sega Mega-CD was a viable option too).
|Sega Mega Drive|
|Topics||History | List of games | Magazine articles | Blast processing|
|Hardware||Japan | North America | Europe | Brazil | Asia | South Korea | Australia|
EZ Games | Heartbeat Personal Trainer | LaserActive | Mega Jet | Mega PC | Mega Play | Mega-Tech System | Nomad | Teradrive | "Consoles on a chip" | Unlicensed clones
|Add-Ons||Power Base Converter | Mega-CD | 32X (Mega-CD 32X) | Mega Modem | Demo System DS-16|
|Controllers||Control Pad | Six Button Control Pad | 6 Button Arcade Pad | Arcade Power Stick 6B | Konami Justifier | MK-1470|
Action Chair | Activator | Arcade Power Stick | Keyboard | MegaFire | Mouse | Mega Stick | Menacer | Remote Arcade System | Ten Key Pad
|Accessories||4 Way Play | Cleaning System | Control Pad Extension Cord | Genesis Speakers | Region converter cartridges | Mega Terminal | Miracle Piano Teaching System | Nomad PowerBack | RF Unit (Mega Drive 2) | SCART Cable (Mega Drive 2) | Stereo Audio Video Cable | Team Player | Video Monitor Cable|
|Network services||Sega Channel | Sega Meganet (Sega Game Toshokan | Mega Anser) | Tectoy Mega Net | Telebradesco Residência | XB∀ND|
|Development tools||ERX 308P | ERX 318P | Sprobe | SNASM68K | SNASM2 (Mega Drive) | SNASM2 (32X)|
|Unreleased||Floppy Disk Drive | Mega Play 1010 | Sega VR | Video Jukebox|