|Fast facts on Sega Mega Drive|
|Variants: Mega Drive 2, Genesis 3, Mega Jet, Nomad, AtGames, Mega Tech, Mega Play, System C, System 18, Amstrad Mega PC, Al-Alamiah AX-660, Al-Alamiah AX-990|
|Add-ons: Mega-CD, 32X, Demo System DS-16, ERX 308P, ERX 318P, Master Mega Converter, MD 8bit Converter, Mega/Master Adaptor, Mega Modem, Power Base Converter, Pro MegaMaster, Sprobe, Super Magic Drive|
|Main processor: 68000|
The Sega Mega Drive (メガドライブ), called the Sega Genesis in North America and Super Gam*Boy (수퍼겜보이) (later Super Aladdin Boy (수퍼알라딘 보이) in South Korea, is a video game console developed by Sega in 1988. The Sega Mega Drive is Sega's third home console, following the SG-1000 (including SG-1000 II) and the Sega Master System (Mark III). It was codenamed the Sega Mark V during development and is part of what is now known as the fourth generation of video game consoles.
The Mega Drive is widely considered to be Sega's most successful video game console. It sold over 40 million consoles worldwide, according to Sega, including more than 20 million in the United States, over 9 million in Western Europe, 3.58 million in Japan, and 3 million in Brazil.
It also had a software library consisting of more than one thousand games released for the system in total. As well as competing with Nintendo's Famicom (NES) and later Super Famicom (SNES) for market control, Sega also found itself fighting against NEC's TurboGrafx-16 (PC Engine in Japan), SNK's Neo Geo, the Atari Jaguar and numerous home computers in one of the biggest "console wars" of all time.
The Mega Drive was envisioned at the next technological step over other video game consoles available at the time. It is a "16-bit" machine, named after its use of a 16-bit CPU (in this case, the Motorola 68000), and was marketed as being superior to popular "8-bit" consoles dominating the market at the time, usually the Nintendo Entertainment System (NES) but sometimes its immediate predecessor, the Sega Master System. 16-bit CPUs had been gaining popularity since the mid-80s, were widely used in arcade machines, and were almost expected to be found in new home computers - it was therefore considered logical that the next "generation" of dedicated video game consoles should follow suit.
The Mega Drive builds on technology found in the Master System (and with adaptors, is fully backwards compatible), though as well as upping the technical specifications for more demanding gameplay, sound and graphics, makes a number of cruicial changes to the design of consoles which continue to this day. Firstly it added a third face button, , to the (now ergonomically designed) control pad. The Mega Drive outputs sound in stereo, and makes an attempt to region lock games through software. Also, when utilising the right cables, the Mega Drive is natively able to produce a clearer image than its rivals (on top of its already higher resolution 320x240 display).
All Mega Drives ultilise a top-loading design (as opposed to the cumbersome VCR-style cartridge loading of the Western NES), while having removable controllers (unlike the Famicom). It was designed from day one to allow hardware expansions, and its use of dark plastic means that the "yellowing" of older systems (from bromine-based flame retardants reacting with oxygen) is less of an issue.
The original Mega Drive measures 28 cm×21.2 cm×7 cm. The top of the unit is split into two components: a circular emboss with the cartridge slot and a tagline (which was omitted on later versions), and a control panel containing the power and reset buttons and the volume slider for the headphones jack. Audio output through the original model was mono through the A/V port, while the headphone jack was used for stereo sound. A third DE-9 port on the back of the unit provided additional peripheral support, though was removed from later revisions.
Asian, Japanese and South Korean models have a cartridge locking mechanism which prevents cartridges from being removed when the power is on (which is why "Eastern" cartridges, as well as the Sonic & Knuckles cartridge and various others, have a cut-out on their left sides). Later runs included the TradeMark Security System, missing in early builds causing small compatibility issues, despite the feature having been planned early on.
1993 saw this cost-reduced redesign (known as the Mega Drive II in Europe, and not explicitly referred to as anything other than "Genesis" in North America), at 22 cm×21.2 cm×5.9 cm, being introduced internationally. One of the major revisions from the original model was the removal of the headphones jack in favor of stereo output through a redesigned 9-pin A/V port. American and European models used a momentary switch for power while non-western models used a left-right switch. Furthermore, the audio mixing circuitry was modified, resulting in noticeably different quality audio output — here is a page with audio samples, provided by little-scale.
A common myth is that the Mega Drive 2 lacks a Z80 — the truth is that it lacks a Zilog Z80. During the Mega Drive's lifetime, Sega received various off-the-shelf chips from different manufacturers, and sometimes would rebrand chips as their own or make them themselves, which is what happened here (and which is why each Mega Drive has a different manufacturer for its 68000). If the Z80 was missing, most games would have no sound (or not all sound). In later revisions, the Z80 was integrated into a custom ASIC which also incorporated the major chips of the system.
The Mega Jet and Nomad were portable Mega Drive systems released near the middle/end of the system's lifetime. The Mega Jet, released in 1994, was originally designed for use on JAL airliners but was later released for Japanese consumers. The Mega Jet is a semi-portable system; the system has a built-in controller but requires an external power supply and a TV. The Nomad was a full portable in its own right, having an integrated screen and sound capabilities, in addition to a battery pack.
The Mega Drive hardware was adapted for arcade use several times over the course of its life. The Mega Tech and Mega Play allowed arcade operators to provide somewhat modified versions of popular Mega Drive games for arcade play — these systems use special cartridges containing games and players can choose from the games plugged into the system. The System C is a different board built from modified Mega Drive hardware, boasting improved color abilities and (in later revisions known collectively as the System C2) improved sample playback. The System C was primarily home to puzzle games — Columns and Puyo Puyo were released on this hardware.
Combination Mega Drive/Mega-CD units were developed over the course of the Mega-CD's lifetime. The Wondermega and LaserActive are standalone consoles; the LaserActive also plays LaserDiscs. The Multi-Mega is a portable audio CD player that can play Mega Drive and Mega-CD games when plugged in to wall power and a TV. The Aiwa Mega CD is a Mega Drive/Mega-CD packed into Aiwa's consumer-level portable CD stereos.
The Teradrive and Mega PC are combination Mega Drive/IBM-compatible PCs made for the Japanese and UK markets, respectively. The three Al-Alamiah computers are combination Mega Drive/MSX computers for the Arabic market.
A variety of companies now make licensed system-on-a-chip units in a variety of fashions that contain single-chip Mega Drive implementations and several licensed ROM images. TecToy-made SoaCs also contain several "new" MD games, however these are believed to be — and likely are — Java 2 Mobile Edition games running on additional hardware. For a full list of SoaCs, see the template at the bottom of the page.
The Mega Drive runs games housed in plastic cartridges uniquely shaped to fit the system. Though the technology exists 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 generally smaller than their Master System/Mark III counterparts, with rounded edges and, in the case of "western" systems, bigger labels layered over the top and front of the cartridge. Region locking exists, albeit in a selection of rather crude forms - the TradeMark Security System, which is missing in many early Mega Drive systems, through software checks implemented manually by developers (which did not begin to feature in new releases until 1993), and differences in cartridge shape. Region locking is easily circumvented through the use of adapters - troubles only arise when dealing with 50Hz/60Hz differences between NTSC and PAL systems, leading some games to run too slowly while others, too fast.
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.
|$400000||$7FFFFF||$400000||Expansion Port Area (used by the Sega CD)|
|$800000||$9FFFFF||$200000||Unallocated (used by the Sega 32X)|
|$A10000||$A10FFF||only various meaningful||System registers|
|$A11000||$A11FFF||only $A11100 and $A11200 meaningful||Z80 control (/BUSREQ and /RESET lines)|
|$A12000||$AFFFFF||only several meaningful||Assorted registers|
|$E00000||$FFFFFF||$10000; mirrored||Work RAM (games usually only use the uppermost mirror, at $FF0000)|
The Sega CD (Mega CD) add‑on, released in 1991, adds the following specifications:
The Sega 32X add‑on, released in 1994, adds the following specifications:
|Sega Mega Drive Hardware|
|Console Variations||Japan | North America | Europe | Brazil | Asia | South Korea | Australia|
|Add-ons||Mega-CD (Multi-Mega | Wondermega | CSD-G1M) | 32X (Mega-CD 32X)
Demo System DS-16 | ERX 308P | ERX 318P| Master Mega Converter | MD 8bit Converter | Mega/Master Adaptor | Mega-CD Karaoke | Mega Modem | Nomad PowerBack | Power Base Converter | Pro MegaMaster | Sprobe | Super Magic Drive
|Controllers||Control Pad | Six Button Control Pad | 6 Button Arcade Pad | Arcade Power Stick 6B | Konami Justifier | MK-1470|
|Network Services||Sega Channel | Sega Meganet (Sega Game Toshokan) | Tectoy Mega Net | Telebradesco Residência | XB∀ND|
|Misc. Hardware||4 Way Play | Action Replay | Cartridge Caddy | Cartridge Soft Pak | Cleaning System | Control Pad Extension Cord | Double Pro Fighter | Everdrive MD | Game Cartridge Organizer | Game Genie | Game Wizard | Genipak | Genesis Speakers | Interceptor Mega Disk | Magicard | Region converter cartridges | Mega Everdrive | Mega Anser | Mega Terminal | Miracle Piano Teaching System | Multi Game Hunter | Power Plug | Megaverter | RetroGen | RF Unit (Mega Drive 2) | SCART Cable (Mega Drive 2) | Sega Power Strip | Stereo Audio Video Cable | StuntMaster | Super Multi-play | Team Player | Tototek MD-Pro | Video Game Organizer | Video Entertainment Center | Video Entertainment Cabinet | Video Monitor Cable|
|Unreleased Hardware||Floppy Disk Drive | Video Jukebox|
|Consoles on a Chip||
Arcade Blast | Arcade Classic | Arcade Master | Arcade Motion Classic | Arcade Motion Dual | Arcade Nano Series | Arcade Portable | Arcade Ultimate | Genesis Gencore | GenMobile | Mega Drive Twin Pads
|Sega Home Video Game Systems|
|SG-1000||SG-1000 II||Mega Drive||Mega Drive II|
|SC-3000||Mega-CD||Mega-CD II||Genesis 3|
|Sega Mark III||Saturn|
|Master System||Master System II|