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The Sega Mega Drive was a 16-bit video game console released by Sega in Japan (1988), Europe (1990) and most of the rest of the world. It debuted under the name Sega Genesis in North America (1989), as Sega was unable to secure legal rights to the Mega Drive name in that territory.

History

Development

Although the Sega Master System had proved a success in Brazil and Europe, it failed to ignite much interest in the North American or Japanese markets, which by the mid-to-late 1980s were both dominated by Nintendo with 95% and 92% market shares respectively. Hoping to dramatically increase their share, Sega set about creating a new machine that would be at least as powerful as the then most impressive hardware on the market - the 16-bit Commodore Amiga and Atari ST home computers.

Since the System 16 made by Sega was very popular, Hayao Nakayama, Sega's CEO at the time, decided to make their new home system utilize a 16-bit architechture. The final design was ported to the arcade, and eventually used in the Mega-Tech, Mega-Play and System-C arcade machines. Any game made for the Mega Drive hardware could easily be ported to these systems.

The first name Sega considered for their console was the MK-1601, but they ultimately decided to call it the "Sega Mega Drive". "Mega" had the connotation of superiority, and "Drive" had the connotation of speed and power. Sega used the name Mega Drive for the Japanese, European, Asian, Australian and Brazilian versions of the console. The North American version went by the name "Genesis" due to a trademark dispute, while the South Korean versions were called Super Gam*Boy (수퍼겜보이) and Super Aladdin Boy (transliterated from 수퍼알라딘보이; this was the Korean version of Mega Drive 2). The Korean-market consoles were licensed and distributed by Samsung Electronics.

Japanese release

The Mega Drive was released in Japan in October 29, 1988 for ¥21,000, almost exactly a year after the first console popularly classed as a 16-bit machine - the NEC PC Engine. Although this initially caused slow sales, the Mega Drive soon eclipsed the earlier machine in popularity. However, after the release of the PC-Engine CD add-on and the Nintendo Super Famicom, the Mega Drive soon lost ground. The Mega Drive was not as popular as the two aforementioned systems in Japan.

European release

The European release was on November 30, 1990 in the United Kingdom and The Republic of Ireland, priced at £189.99. The first UK shipment of 30,000 units was sold at retailers Comet, Dixons, Rumbelows and Toys R Us (Foulger, 2000).

Brazilian release

The Mega Drive was released by Tec Toy in 1990, only a year after the Brazilian release of the Sega Master System. Tec Toy also released the internet service Mega Net, and made exclusive games like a port of Duke Nukem 3D The Mega Drive is still manufactured in Brazil, with many games built into the console (the latest one has 71 Mortal Kombat 3, Sonic the Hedgehog 2, Mortal Kombat II, Super Monaco GP, Castle of Illusion, Ultimate MK3, Ayrton Senna's Super Monaco GP II, Fifa 97, Moonwalker and Sonic Spinball [http://72.14.207.104/search?q=cache:IQ8BNxOM24QJ:www.fighters.com.br/forum/lofiversion/index.php/t2072.html+%22Sonic+R%22Nights%2BTec+Toy&hl=pt-BR&gl=br&ct=clnk&cd=7" target="_blank" >*.

North American release and further development

Sega announced their North American release date for the system in 1987, becoming the second console to feature a 16-bit CPU (the first one being the Mattel Intellivision) and the first to feature single instruction 32-bit arithmetic. U.S. sales began on January 9, 1989 in New York City and Los Angeles with a suggested retail price of States Dollar|$" target="_blank" >*200 at launch. It was released in the rest of North America on September 15 with the price reduced slightly to $190. The Genesis initially competed against the 8-bit NES, over which it had superior graphics and sound. Nonetheless, it had a hard time overcoming Nintendo's ubiquitous presence in the consumer's home and the huge catalog of popular games already available for it. In an attempt to build themselves a significant consumer base, Sega decided to focus on slightly older buyers, especially young men in their late teens and early 20s who would have more disposable income and who were anxious for more "grown-up" titles with more mature content and/or more in-depth game play. As such, Sega released titles such as Altered Beast and the Phantasy Star series. Although the NES and Nintendo's impending SNES were still threats to Sega's market share, they had forced the theoretically competitive TurboGrafx 16 system into relative obscurity, thanks in part to NEC's poor North American marketing campaign.

Eventually, the main competition for the Genesis became Nintendo's 16-bit SNES, over which it had a head start in terms of user base and number of games, reversing the problem Sega had faced against the NES. The Genesis continued to hold on to a healthy fan base composed significantly of RPG and sports games fans. The release of Sonic the Hedgehog in 1991 began to threaten Nintendo's up-to-then stranglehold on the number one console position in the USA. Sonic was released to replace former mascot Alex Kidd, and to provide the "killer app" that Sega needed. This sparked what was arguably the greatest console war in North American video gaming history.

By 1992, Sega was enjoying a stronghold on the market, holding a 55% market share in North America. Faced with a slight recession in sales and a brief loss of market share to the SNES, Sega again looked to Sonic to rejuvenate sales. The release of the highly anticipated Sonic the Hedgehog 2, coinciding with an aggressive ad campaign that took shots at Nintendo, fueled Genesis sales a while longer and boosted Sega's market share percentage back up, to an astounding 65%. Less than a year later, in 1993, Sega released a redesigned version of the console at a newly reduced price. By consolidating the internal chipset onto a smaller, unified motherboard, Sega was able to both physically reduce the system's size and bring down production costs by simplifying the assembly procedure and reducing the number of integrated circuits required for each unit.

Aside from the release of the Sega CD and 32X add-ons for the Genesis/Mega Drive, Sega's last big announcement came in the form of a partnership with Time Warner in the U.S. to offer a subscription-based service called Sega Channel, which would allow subscribers to "download" games on a month-by-month basis.

Decline in market share

The failures of the Sega CD and 32X, a lack of effective advertising, and disputes between Sega of America and Sega of Japan had taken their toll on the company. By 1994, Sega's market share had dropped from 65% to 35%, and the official announcements of newer, more powerful consoles, such as the Saturn, Playstation, and N64 signaled that the 16-bit era was drawing to a close. Interest in the Genesis suffered greatly as a result, compounding its already falling sales. In 1996, less than a year after the debut of their Saturn console, Sega quickly brought their participation in the 16-bit era to an end by discontinuing production of the Genesis and its associated accessories. This obviously angered consumers around the world who had bought the Sega CD and 32X attachments only to see Sega abandon all support. This can, at least in slight, be seen as a contributing factor to the downfall of Sega as a console manufacturer. (see Video game market).

Resurgent popularity

In recent years, there has been something of a revival of interest in the Mega Drive/Genesis, led largely by the grey market trade in both unlicensed cartridges (for instance, the biblically themed output of Wisdom Tree) and dumped ROMs, which are played through emulators such as Kega Fusion, GENS, or Genecyst. There is also a trend towards home programming, using the PC-based SGCC.

In the 2000s, there came a trend toward plug-and-play TV games, and Radica has released licensed, self-contained versions of the Sega Mega Drive/Genesis in both North America (as the Play TV Legends Sega Genesis) and Europe (as the Sega Mega Drive 6-in-1 Plug 'n' Play), which contain six popular games in a small box and control pad. It does not have a cartridge slot, and thus is a dedicated console. However, Benjamin Heckendorn, of Atari portablizing fame, has proven that it is possible to connect a cartridge slot with some soldering.

The GameTap subscription gaming service includes a Genesis emulator, and has several dozen licensed Genesis games in its catalog.

On March 23, 2006, it was announced at the Game Developers Conference in San Jose California that Nintendo will offer backwards compatibility with the Sega Mega Drive/Genesis with the Wii home console. However it is not yet clear whether this includes all titles in the Console's Back Catalogue. The announcement also stated that PC Engine games would be available for download to the virtual console.

On May 22, 2006 Super Fighter Team released the Beggar Prince, a game translated from a 1996 Taiwanese original. It is the first commercial Sega Megadrive game since 1998 in the North American market.

Variations of the Mega Drive/Sega Genesis

During its lifespan, the Mega Drive and Genesis quite possibly received more officially licensed variations than any other console. While only one major design revision of the console was created during its lifespan, each region has it's own peculiarities and unique items, while other variations were exercises in reducing costs (such as the removal of the little-used 9-pin EXT. port) or expanding the capabilities of the Mega Drive/Genesis.

Technical specifications

CPU

Main processor: 16-bit Motorola 68000 (or equivalent)
  • Runs at 7.61 MHz in PAL consoles, 7.67 MHz in NTSC consoles.
  • Some systems contained clones of the Motorola 68000 manufactured by Hitachi and Signetics.
  • Signetics 68K only found in early revisions as this CPU is known to be inefficient.
Secondary processor: 8-bit Zilog Z80 (or equivalent)
  • Runs at 3.55 MHz in PAL consoles, 3.58 MHz in NTSC consoles
  • Used as main CPU in Master System compatibility mode.

Memory

Boot ROM: 2 KB
  • Known as the "Trademark Security System" (TMSS)
  • When console is started, it checks the game for certain code given to licensed developers
  • Unlicensed games without the code are thus locked out
  • If a game is properly licensed, the ROM will display "Produced by or under license from Sega Enterprises Ltd."
  • Boot ROM is not present on earlier versions of the Mega Drive and Genesis
  • Some earlier games not designed for the TMSS may not work in later consoles

Main RAM: 64 KBytes

  • Part of M68000 address space

Video RAM: 64 KBytes

  • Cannot be accessed directly by CPU, must be read and written via VDP (Video Display Processor - see below)

Secondary RAM: 8 KBytes

  • Part of Z80 address space
  • Used as main RAM in Master System compatibility mode

Audio RAM: 8 KBytes

Cartridge memory area: up to 4 MBytes (32 Megabits)

  • Part of M68000 address space
  • Game cartridges larger than 4 MBytes must use bank switching

Graphics

The Mega Drive has a dedicated VDP (Video Display Processor) for playfield and sprite control. This is an improved version of the Sega Master System VDP, which in turn is derived from the Texas Instruments TMS9918. It contains both mode 4 (for Master System compatibility) and mode 5 (for native Genesis games). However, Master System programs can switch the VDP into mode 5 and make use of advanced VDP features. This page only discusses mode 5 capabilities.

Planes: 4 (2 scrolling playfields, 1 sprite plane, 1 'window' plane), per-tile priority

Sprites: Up to 64 (32H)/80 (40H) on-screen, 16/20 per line, 256/320 pixels per line, per-sprite priority

Palette: 512 colors (1536 using shadow/highlight mode)

On-screen colors: 64 × 9-bit words of color RAM, 4 lines of 15 colors plus transparent, allowing 61 on-screen colors (up to 1536 via raster effects and shadow/highlight)

Screen resolution: 256x224 (32Hx28V), 320x224 (40Hx28V), 256x240 (32Hx30V, PAL only), 320x240 (40Hx30V, PAL only)

  • Interlace mode 1 provides no increase in resolution, but still generates a true interlaced signal
  • Interlace mode 2 can provide double the vertical resolution (i.e. 320×448 for NTSC, 320x480 for PAL). Used in Sonic 2 for two-player split screen

Scroll size: Width and height independently set to 32, 64, or 128 cells as VRAM allows

Sound

Main sound chip: Yamaha YM2612
  • Six FM channels, four operators each; channel 6 can be used for PCM data or as a regular channel
  • Programmable low-frequency oscillator and stereo panning

Secondary sound chip: Texas Instruments SN76489 compatible device built into VDP.

  • Four-channel PSG (Programmable Sound Generator)
  • Three square wave channels, one white noise channel
  • Programmable tone/noise and attenuation
  • Used for Master System compatibility mode as well as to supplement FM
  • Different random noise generation compared to a real SN76489/SN76489A chip

Inputs and outputs

RF output: RCA jack connects to TV antenna input
  • Exists on original model European and Asian Mega Drive and North American Genesis only
  • Other models must use external RF modulator which plugs into A/V output

A/V output: DIN connector with composite video, RGB video, and audio outputs

  • Mega Drive and the first model Genesis have an 8-pin DIN socket (same as Sega Master System) which supports mono audio only
  • Mega Drive 2, Multimega, and other models have a 9-pin mini DIN socket with both mono and stereo audio

Power input: positive tip barrel connector. Requires 9-10 volts DC, 0.85-1.2 A depending on model

Headphone output: Amplified 3.5-mm stereo jack on front of console with volume control

  • Exists only on original model Mega Drive and Genesis units
  • Provides stereo audio on models which have the mono 8-pin DIN A/V output
  • Also suitable for passive speakers
  • Can be used for mixing audio from the SegaCD

"EXT" port: DE-9F (9-pin female D-connector) on back of console

  • Used with the Meganet modem peripheral, released only in Japan
  • Exists on all first-model Japanese and Asian Mega Drive units, and on early American Genesis and European Mega Drive units
  • May have been used for game selection on arcade adaptations of the Mega Drive / Genesis console

Control pad inputs: two DE-9M (9-pin male D-connectors) on front of console

Expansion port: Edge connector on bottom right hand side of console

  • used almost exclusively for Sega Mega-CD connection
  • not present on Genesis 3 model
  • also used for the Sega Genesis 7 Cart Demo Unit in stores.

Power Base Converter

One of the key design features of the console is its compatibility with its immediate predecessor, the Master System. The 16-bit design is based upon the 8-bit design, albeit enhanced and extended in many areas. As the cartridge slot is of a completely different shape, Sega released the Power Base Converter, a separate device that sat between a Master System cartridge and the new shape of cartridge slot. Due to the high level of backwards compatibility, the Power Base Converter does not contain any Master System components - it is essentially a method of fitting a square peg into a round hole. The converter contained 2 slots. The top slot was for cartridge based games. The front slot was for card based games. The Power Base Converter would be fully compatible with the Genesis 2, were it not for the different shape of the Genesis 2's casing. One can remove the PBC casing, allowing it to work on a Genesis 2.

In order to achieve backwards compatibility, the original Master System central processor and sound chip (the Z80 and SN76489) are included in the Mega Drive/Genesis and the new Video Display Processor is capable of the Master System VDP's mode 4 (though it cannot run in modes 0, 1, 2, or 3). Once an 8-bit game is inserted, the system's bus controller chip (later integrated with the I/O chip into a single multi-purpose ASIC) will put the Z80 in control leaving the 68000 idle.

Both 2-button Master System pads and standard Genesis pads can be used to play SMS games. Due to slight differences in how the Genesis pads operate, some Master System games may inadvertently cause the wrong set of inputs to be selected in a 3/6-button pad and prevent input from working properly. In this case a Master System controller must be used. Like the Master System, the PAUSE button is not part of the gamepad connector and instead is implemented as a pushbutton switch on the Power Base Converter or similar devices.

In Japan, the device was known as the Mega Adaptor and the PAL variant was called the Master System Converter. In order to make it compatible with the new Mega Drive II, a second PAL converter, the Master System Converter II, was also released.

Trivia

  • An adapter to make the machine capable of playing Game Gear games never existed. Although based upon the Master System, the Game Gear's hardware is sufficiently different that such a device would require extra hardware for complete compatibility.
  • Majesco's Genesis 3 (single-chip and dual-chip versions) retains the Mode 4 support but has the Master System compatibility removed from the bus controller logic. This renders the Power Base Converter or any other adapter useless. 68000 software can still enable and use Mode 4, however.
  • One of the 68000 instructions, TAS, is intended for semaphore communication in multiprocessor machines and locks the 68000 bus during memory access. The Sega hardware did not support this unusual bus cycle and ignored the write-back phase. One game, Disney's Gargoyles, uses the TAS instructions and expects it not to write to memory and as a result it works on original Sega machines but not the Majesco Genesis 3 which has correct support for TAS.
  • It is possible to overclock the Motorola 68000 CPU in some cases in excess of 300% (the current known world record is 25.4 MHz), though it may not be completely stable beyond a certain point on each console. In a guide at Epic Gaming, the How-To carefully explains this process. Some chips can clock higher than others, and other factors come into play such as how tolerant the system's arbiter, RAM or VRAM are to overclocking. You can perform the process without buying anything (if you have wire, solder, a soldering iron, and 1 or 2 switches), though you can only overclock the chip to 13.4 MHz without the purchase of inexpensive oscillators. Overclocking may seem a bit odd; however, in some games, such as Sonic the Hedgehog 2, the 68000 CPU would struggle to display many sprites or crunch a heavy level of physics calculation; for example, after you get hit and the rings fly out of your character. Overclocking the chip by even 3 MHz can totally eliminate this. The overclock can be achieved by simply linking with a wire the chip's CLK pin (usually pin 15, it depends on the chip) to pin B15 of the cartridge slot's pin, which carries a 13.4 MHz signal, thus overclocking the chip; however it is advised to switch to 13.4 MHz after boot with a halt/clock switch pair (as is outlined in the guide) to reduce the likelihood of glitches or sound problems. Note that the 13.4 MHz output directly relates to the screen width and causes the speed to vary as the game sets up the display (256-pixel mode is 10.73 MHz, in contrast to 13.4 MHz for 320-pixel mode)
  • Another curious modification is to replace the stock 68000 processor with a 68010. Since the CPU isn't socketed, this requires the removal of the old CPU, and soldering in of the new. The 68010 is a pin-compatible, 'enhanced' version of the 68000, which is a bit more efficient internally and offers some new features. According to modder Robert Ivy, upgrading the CPU to a 68010 does not necessarily make the games run faster, it just reduces how much they slow down in intensive situations. Also, for some reason, the DAC's digital audio output sounds cleaner and less distorted. However, the 68010 is not 100% object code-compatible with the 68000, so machines modified with a 68010 processor are not able to run certain games properly; such as Sonic 3, Sonic and Knuckles, Street Fighter II, Red Zone, and a few others.
  • Contrary to popular belief, Model MK-1631 (Mega Drive/Genesis 2) does have a Z80 CPU. Depending on the board revision, the system has either a Zilog Z84C00 or a Custom Sega 315-5676 or similar. Because the Z80 is used for sound production by many games it is a necessary component. The idea that the redesigned machine has no Z80 came from reports of incompatibility between those models and the Power Base Converter, which provides Sega Master System compatibility, but the true prohibiting factor is the shape of the device. The redesigned cartridge port is too far forward on the system to connect a Power Base Converter without first removing its plastic housing.
  • Even though software support ended in 1998, a new commercial game called Beggar Prince was released for the system in the spring of 2006.
  • There is a song promoting the console featuring the Genesis slogan "Genesis does what Nintendon't".

Sales

The Mega Drive sold over 35 million units worldwide.*

Bibliography

Foulger, C. (2000). Sega Mega Drive Frequently Asked Questions, version 2.2.
Maxim, et. al. (2003) SN76489 notes, 5th revision

See also

Related systems

External links

Technical Information

Sega Mega Drive/Sega Genesis | Fourth-generation video game consoles

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This article is licensed under the GNU Free Documentation License. It uses material from the "Sega Mega Drive/Sega Genesis".

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