Sega CD
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Sega Mega-CD

Manufacturer	Sega
Type	Video game console add-on
Generation	Fourth generation
First available	JP December 1, 1991verification needed NA October 15, 1992 EU April 1993
Discontinued	1995
CPU	MC68000 @ 12.5 MHz
Media	CD-ROM, CD+G
System storage	Internal RAM
Units sold	6 million1
Successor	Sega 32X

The Sega Mega-CD (メガCD, Mega Shī Dī^?) is an add-on device for the Sega Mega Drive that was released in Europe, Australia, New Zealand, Japan, and North America. In North America, it was renamed Sega CD, as the name Mega CD bore no obvious associative meaning in that market where the console used the name "Genesis" instead of "Mega Drive" because of copyright reasons. The device upgraded the Mega Drive with a CD-ROM drive that allowed the user to play games on a CD-ROM and added some additional electronic hardware functions. In addition to CD-ROM based games, it also played audio CDs and CD+G discs.

The development of the Mega-CD was confidential; game developers were not made aware of what exactly they were working on until the add-on was finally revealed at the Tokyo Toy Show in Japan^{citation needed}. The Sega Mega-CD was designed to compete with the PC Engine (TurboGrafx-16) in Japan^{citation needed}, which had a separate CD-ROM drive.

The Sega Mega-CD was not meant to compete with the Super Famicom (Super Nintendo Entertainment System outside Japan). This posed a problem in the markets outside of Japan, where the PC Engine did not fare very well, and the expectation was that the Mega-CD would be in competition with Nintendo^{citation needed}. (The Genesis did compete directly with the Super Nintendo in North America, which makes this statement confusing.)

The Mega-CD connected to the Mega Drive via the expansion port on its right side at the bottom edge. The first version of the system sat under the Mega Drive console and loaded CDs via a motorized tray. The tray was opened when the Reset button on the Genesis was pressed while the Mega-CD's startup screen was displayed. The second version of the system, dubbed Mega-CD 2, had the CD-ROM drive relocated to the right of the Sega Mega Drive system, changed to a top-loading CD-ROM drive with a lid, with the lid opened by a mechanical latch button on the front right corner. This revised model was meant primarily to be used with the redesigned Sega Mega Drive 2. However, the original model of the Sega Mega Drive could still be used with the addition of an extension--just a two-part molded plastic block--that allowed the system to firmly sit on the add-on without overhanging the edge. The Mega-CD 2 (at least as sold as the Sega CD in North America) included all parts, including the extension block, needed to attach it to any Genesis model. As the CD drive was now to the side of the Mega Drive, the Mega-CD 2 hd a much lower profile than the original, (The Sega Mega Drive still sat on top of the system, but to a much lesser extent than before). Also, the switch from a software-controlled motorized CD tray to a mechanically latched lid made it possible to remove the disc while a game was running and the disc was spinning, requiring more care and discretion on the part of the user.

Markets

Japan

The Aiwa Mega CD, a hybrid Mega CD / Sound Minisystem manufactured by Aiwa

The Mega-CD was released first in Japan in December 1, 1991^{verification needed}. Its retail price was about ¥49,800. Initially, it was a great success^{citation needed} because of the inherent advantages of CDs (high storage capacity and the low cost of media).

Despite having been on sale for over 2 years, by March 1994 the MEGA-CD had only sold 380,000² units in Japan, which meant that only 11% of Japanese Mega Drive owners had purchased the add-on unit.

North America

The Sega CD had been announced at the Chicago CES on January 1992. The Mega Drive had been renamed to Genesis for the console's release and Sega of America chose to repeat the operation with the Mega CD, renaming it Sega CD^{citation needed}.

Many people felt there was not enough value for the price^{citation needed}. Moreover, the game experience was little improved^{citation needed}. Players came to have high expectations for the add-on, and Sega even promised that the Sega CD would allow a higher color palette than the Genesis^{citation needed}. Graphically, most games ended up looking not much better than normal Sega Genesis games^{citation needed}, although the sound quality was higher, thanks to the CD format of the games. The advertising boasted full-motion video clips and CD audio soundtracks. Games delivered these, though because of the limited color palette of the Genesis video display hardware and limited data bandwidth of the system, especially considering that the CD-ROM drive was only a 1X speed unit, motion video was heavily dithered and usually limited to a rectangle in the center of the screen about 1/4 of the full screen size. CD games also offered more complex levels and more levels; the game Sonic CD notably made a point of leveraging this.

Europe

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PAL Mega Drive II and Mega-CD II

In Europe the Mega-CD was thought to be overpriced. It was released in April 1993 in the United Kingdom.^{citation needed} Unlike the Mega Drive, which was a very successful console in Europe, only 60,000 of the 70,000 Mega-CDs shipped to Europe were sold by August 1993.^{citation needed}

Some European countries (Spain for instance), would not get the original Mega-CD, but the Mega-CD 2, which also slowed sales.^{citation needed}

Australia

The Mega-CD was released on 19 April 1993 in Australia.

Brazil

The Sega CD 2 was launched in the Brazilian market exactly at the same time of the North American release. Since the original Sega CD was never released there, it was simply called "Sega CD". However, because several Mega-CD units imported from Japan were already in the market, it was informally known as "Mega-CD". It was manufactured locally by Tec Toy.

Reception

Sega wanted to showcase the power of the Mega CD, and so focused on "FMV" games rather than taking advantage of the extra storage space of the CD media. Sega insisted on licensing and producing primarily "full motion video" games similar to earlier Laserdisc games, that were universally panned by game reviewers. The limited 512-color palette of the system, combined with the processor not being well-suited for video, did not lend itself well to reproducing video, resulting in grainy video in most games.

Another criticism of the software library was that most titles consisted of Shovelware, in which a developer takes an existing title and adds minor new content (usually a CD audio soundtrack, or video sequences) while not expanding the original game itself. Few titles received major changes, but two exceptions were Earthworm Jim which featured additional levels and game changes, and The Amazing Spider-Man vs. The Kingpin, which featured many changes, which drastically restructured the game, making it less linear, and adding animated cut scenes.

Despite a somewhat lackluster library of games, the console introduced very famous franchises. The Lunar series, which despite the relatively narrow circulation the two titles on the Mega CD received, went on to be critically acclaimed and became a cult classic, with both games receiving remakes for the PlayStation and Sega Saturn in the late 90's; and a prequel to the series for the Nintendo DS in 2005. The English publisher of the two Lunar titles, Working Designs, also published another RPG for the platform, entitled Vay. While it received generally positive reviews, the game did not obtain the same popularity as the Lunar titles. Working Designs also published Popful Mail for the Mega CD. Another notable title was the cult-classic Snatcher, a cyber-punk digital comic released by Konami and designed by Hideo Kojima and the only version of the game released in English.

One exclusive game that was published for the Mega CD is the now famous Sonic the Hedgehog CD, or Sonic CD. Sonic CD is praised for having good graphics, superior CD sound, and an innovative style of stages, having four versions of each of the three zones in each stage. Many fans praise the game as one of the best of the series for these reasons.

Models

The following models were released:

• Sega Mega-CD I (Sega CD I in North America)
• Sega Mega-CD II (Sega CD II in North America). Designed for the Mega Drive 2 / Genesis (second model) and to reduce manufacturing costs

JVC Wondermega Model 1

• JVC Wondermega Model I (JAPAN-ONLY: combination Megadrive/Mega CD player with enhanced sound, video and karaoke capabilities and an mechanized CD tray lid. Also included MIDI functionality. Sega themselves released a variation of this unit with slight cosmetic changes, but functionality remains identical - Branded as Sega Wondermega)
• JVC Wondermega Model II (JAPAN-ONLY: a second model with a different case design and wireless controller functionality built in. The mechanized CD tray was omitted in favour of a more conventional spring loaded tray design. Otherwise, functionally identical to the Wondermega I. This model was stripped down released in the US as the X'Eye).
• Sega Multi-Mega (called Sega CDX in North America). A portable CD player that plays both Mega Drive and Mega-CD games, as well as audio CDs, and CD-G discs. Resembling a slightly longer version of the typical portable CD player of the day.
• Pioneer LaserActive Sega Mega-CD module, an add-on device available for the LaserActive system

Technical specifications

The Sega Mega-CD specifications were as follows:³

CPU

The main CPU is a 12.5-MHz 16-bit Motorola 68000 processor. The Mega Drive/Genesis has the same processor, but at a lower clock rate of 7.67 MHz (NTSC) / 7.61 MHz (PAL). In the combined system, both processors run concurrently for Mega-CD games, and the Mega-CD processor is idle for Mega Drive games.

Graphics

• Graphics Processor: Custom ASIC
• Number of simultaneous colors on screen: 64 out of 512
• Display resolution: 320 x 224 pixels and 256 x 224, video size from ¼ to full screen
• Advanced compression scheme
• Software-based upgrade
• Scaling and rotation effects

RAM

• Main RAM: 6 Mbit (upgrade from the Mega Drive's 64kbyte)
• PCM samples: 512 kbit
• CD-ROM data cache: 128 kbit
• 64 kbit Internal Backup RAM (for storing saved games, scores, etc. for CD games)

Storage

• 500 MB CD-ROM discs (equivalent to 62 minutes of audio data)
• ¼ screen B/W footage video: 1.5 to 4 hours
• ¼ screen color footage: 45 minutes
• CD-ROM drive transfer rate: 150 kB/s (1x)

(Above specs prior to compression)

BIOS

• Size: 1 MBit
• Used for games, CD player, CD+G and karaoke
• Access time: 800 ms

When the Mega Drive + Mega CD is powered on, the Mega Drive CPU gets control first. If a cartridge is inserted, the Mega Drive ROM starts it, and the Mega-CD remains idle, except for the audio mixer, which passes through the Mega Drive audio to its RCA outputs. If the cartridge slot is empty at power-up, the Mega-CD CPU gets control and starts its BIOS, which checks the disc while displaying a Mega-CD (or Sega CD) title animation with music utilizing the sound hardware of both the Mega Drive and the Mega-CD together (at least in Sega CD versions). (This screen displays the ROM version in the upper-right corner, at least in versions 1.10 and 2.00.) If a game disc is inserted, it automatically loads the game after a few seconds, or immediately if Start is pressed on the controller. If a regular audio CD or a CD+G disc is inserted, it waits for button A, B, or C on the first controller to be pressed, then starts the GUI CD/CD+G player software in ROM. It will also run this software on a game disc if A, B, or C is pressed before the game auto-starts. From the CD player, it is also possible to enter a utility to manage items in the game backup RAM and RAM carts, or to start an inserted Mega-CD game disc (without resetting the console). If no disc is inserted, it prompts on screen for one while playing the title animation and music. Except when a game disc is in the drive, if no button is pressed at the Mega-CD title screen, the animation and music will loop indefinitely. In the original mega-CD model which has the motorized front-loading tray, pressing reset while the title screen is displayed will open the tray (eject the disc) or close it (load the disc). At all other times (without a cartridge inserted), pressing reset will return to the Mega-CD title screen, but will not open the tray. It is impossible to open the motorized tray with a cartridge inserted, as the BIOS which controls it will not run then. In the later version of the Mega-CD with the top-loading drive, resetting or powering off may leave the disc spinning, and the only way to stop the disc before opening the tray is to switch off the system and wait 15 to 30 seconds for it to spin down (under the light friction of the spindle motor bearings) or to enter the CD player mode and play or pause the disc, then stop (in BIOS v2.00, maybe others). After the disc can be heard to spin down while the lid is closed, whereas just pointing to Stop and pressing a button will not spin down the disc when the player is not in play or pause mode.

Audio

The Mega-CD adds the Ricoh RF5C164 chip, which gives 8 extra sound channels, all capable of sampled sounds, to the Mega Drive's YM2612 and SN76489 chips.

• Sound format: Stereo PWM
• Clock frequency of source: Up to 12 MHz
• Sound channels: 8
• Maximum sample rate: 32 kHz (44.1 kHz for CD-DA)
• Wave data width: 8 bits
• 16 bit DAC
• 8x internal over-sampling digital filter
• Frequency Range: 20 Hz - 20 kHz
• Signal-to-Noise Ratio: > 90.0 dB @ 1K
• Channel Separation: > 90.0 dB
• Output: RCA stereo Pin Jack x2 (L/R) / SCART cable
• Mixing Input Port for sound on the original Sega Mega Drive / Sega Genesis Model via the RCA jacks on the back of the Sega CD unit.

Other

• Dimensions: 301 mm × 212.5 mm × 112.5 mm
• Weight: 1.4 kg (3.1 lb)

Accessories

• Few accessories were released for the Mega-CD. The most notable being an external memory card that came in the form of a Mega Drive cartridge. Titled the "CD Backup RAM Cart", it was placed in the Mega Drive slot like a normal Mega Drive game, and the Mega-CD would detect this cartridge upon booting up. Games could either be saved directly to it (on the titles that supported it) or to copy/transfer game saves to and from the Mega-CD's internal RAM. Complete backups were possible as the CD Backup RAM Cart contained 16 times the amount of RAM as the Mega-CD (1 Mbit, or 2045 Game Save Blocks, compared to the Mega-CD's 64Kb, or 125 Game Save Blocks.)
  

  

  The CD Back-up RAM Cart Logo

• A Light gun named "The Justifier" was also released bundled with Lethal Enforcers.

• A multi-functional cartridge called "Megacart" was released in 2006. It works as a region converter, RAM cart and can flash cart games.

Graphic trivia

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While the system was in development, several US video game magazines such as Electronic Gaming Monthly and Gamepro had published reports that the Sega CD was going to be able to display more on-screen colors than the Sega Genesis. It appears that there had been some discussion about upgrading the hardware in the Sega CD to compete with the color capabilities of the Super Nintendo, but it was vetoed.

A common myth surrounding the Mega-CD is in regard to the number of colors it can display on-screen. Like the unexpanded Mega Drive/Genesis, the published specifications of the Mega-CD indicate that the system can produce up to 64 colors on-screen out of a global palette of 512 (the same color palette of the Mega Drive). However, many people claim that some games, such as Snatcher, Jurassic Park and Eternal Champions, exceeded the on-screen limit with the use of programming tricks, achieving 112, 192, even 256 colors simultaneously. Some versions of this rumor claim that there was a version of the Cinepak video codec that could render FMV in 256 colors on the Mega-CD as well.

The idea of displaying more than 64 colors at once in Mega-CD games is not groundless. What is not widely realized, however, is that the Mega-CD breaks this limit with the same methods that can be executed on an unexpanded console, and also that these methods are all severely limited in practical use.

The most common way of displaying extra colors is with the use of raster effects, which involve simply changing the on-screen color palette in between TV scanlines as the picture is being drawn. Sonic games use this to make underwater effects. A lesser known trick is to use the priority bit of a pixel for color purposes, allowing any color to have 3 shades (normal, bright and dim) and effectively tripling the number of colors available onscreen (an effect similar to the Amiga's Extra Half-Brite mode). However, this trick compromises the video display processor's capabilities so drastically that it was rarely ever used, especially for in-game graphics. Finally, many developers simply relied on dithering, a simple artist's method of drawing pixels of two similar colors in an alternating, checkerboard-like manner, and relying on the inaccuracy of composite or RF video signals to blend the colors together into a third color. On a side note, this same method could be used to make a fake transparency just by leaving every other pixel blank.

The programming technique which many mistakenly believe could be used to display extra colors on the Mega-CD is called HAM, or Hold And Modify. This complicated trick was used on the Amiga with the same goal of raising the on-screen color limit. However, the Amiga could also use raster effects, and this is where the confusion most likely started. At some point, it was probably said that a trick similar to one used on the Amiga could be used with the Mega-CD to display extra colors on-screen. Since people knew there was a trick to get extra colors out of the Amiga called HAM, they may have then assumed that the Mega-CD could use HAM as well. However, the Mega-CD has no support for this or a similar function at all whereas the Amiga's graphic chip was designed for it.

Mega-CD/Sega CD originated titles

• Jurassic Park - Different from the cartridge version, this heavily relies on FMV for game movement and plot progression. (An easter egg can be seen by using the rock on the computer.)
• Sewer Shark - A Digital Pictures FMV game for one player. It was the pack-in game with the second model Sega CD in North America. It uses no CD audio tracks, but the disc contains one short one as a joke. (A phone rings, and a man answers, "Good Afternoon, Digital Pictures. A chorus of people recite a three-syllable phrase three times, in reversed audio. It may be a Beatles reference.)
• Sonic CD - Taking advantage of the large capacity of the CD-ROM format compared to Mega Drive cartridges, this game features four versions of most levels: Past, Present, Bad Future, and Good Future. Includes a CD audio background music for all but the Past versions, but due to limited audio space on the disc most songs are trimmed to only 2-3 minutes with a fadeout and looped.

Mega Drive/Genesis titles re-appearing on CD

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See also: List of Sega Mega-CD games

Several Mega Drive/Genesis titles (As well as franchises appearing on other platforms) were ported to Sega's CD format. The CD counterparts usually offered reworked soundtracks, and slightly improved graphics. Some of these titles and their differences:

• After Burner III - A port of the Japanese arcade game Strike Fighter. This particular title does feature a hard-rock/heavy-metal re-produced soundtrack of the majority of the original After Burner/After Burner II music.
• Batman Returns - One of the more lengthy ports. The game features the full side-scrolling game of Batman Returns from the Mega Drive/Genesis, as well as new driving action stages in between each side-scrolling hub. An original soundtrack created by Spencer Nilsen (Ecco the Dolphin, Sonic CD) features many dark symphonic tunes mixed with batches of rock/heavy-metal. The new driving modes show off much of the Sega CD's added power with big sprites and a lot going on with little slowdown.
• Brutal: Paws of Fury - The Sega CD version of this animal-based fighting game added two new intros, new CD soundtrack, two new characters, new voice clips, smoother animation, and a Bonus section in the main menu. The bonus section had an "Outtakes" video, a sound test, and other information.
• Columns - appeared as part of the Sega Classics Arcade Collection and featured a new soundtrack.
• Chuck Rock - A direct gameplay port. Visuals come out as a little bit smoother than other versions, and the game includes a re-produced CD soundtrack.
• Chuck Rock 2: Son of Chuck - Title includes a re-done CD soundtrack as well as FMV intro and ending video sequences, detailing the storyline.
• Earthworm Jim: Special Edition - This direct port of the PC game also doubles as a music CD.
• Ecco the Dolphin - A direct port of the Genesis/Mega Drive game. There are no differences in gameplay, visuals, or sound effects, except for some new levels. The soundtrack is, however, a completely new symphonic work by Spencer Nilson. The disc doubles as a music CD. (It is a mixed mode CD, having a data track containing an ISO-9660 filesystem followed by CD audio tracks, all in a single session.)
• Ecco: The Tides of Time - A direct port of the Genesis/Mega Drive game with a re-vamped CD soundtrack and lengthy CG FMV sequences illustrating the story throughout the game. Disc doubles as a music CD. (Like Ecco the Dolphin, this is a mixed mode CD, having a data track containing an ISO-9660 filesystem followed by audio tracks, all in a single session.)
• Eternal Champions: Challenge from the Dark Side - More of a full-on sequel to the original Eternal Champions. With all of the enhancements and editions (Characters, fatalities, CG sequences, re-worked soundtrack and fresh story elements), it should not be confused as a direct port.
• Final Fight CD - Up until Final Fight was re-released in the recent Capcom Classics collections for PlayStation 2, XBOX, and PSP, the Sega/Mega CD version of the game offered the most-complete experience. Guy is a playable character, the game takes advantage of the Sega CD's added power with smoother animation than other previous ports (SNES/SFC), and also incorporates simultaneous two-player gameplay, along with extended intro and ending sequences and a revamped musical score with real instruments on a CD-Player-Friendly soundtrack. A time-attack mode is also available, where one or two players are pitted against as many enemies as they can handle within a defined amount of time.
• Flashback: The Quest for Identity - A port of the PC game. Includes all CG FMV sequences and each stage now features its own full-length, CD-quality music track (versus the short music clips that played sparsely throughout the game in the original PC game and console ports).
• Flink - Has more levels than the Sega Genesis/Mega Drive port of the game and the soundtrack from the original Amiga CD32 port.
• Golden Axe - appeared as part of the Sega Classics Arcade Collection and featured a new soundtrack.
• Heart of the Alien - A port of Out of This World, which originally debuted on the Amiga, PC, Mega Drive, and SNES. Sega CD version includes smoother animation and quicker gameplay overall with less slowdown, a revamped CD soundtrack, as well as the full sequel, Out of This World 2: Heart of the Alien.
• Lethal Enforcers - Identical to the earlier console ports, although it includes the full arcade soundtrack, as well as small video clips. A lightgun bundle was released.
• Mickey Mania: The Timeless Adventures of Mickey Mouse - The Sega CD version is identical gameplay-wise to the Genesis version, but includes additional voice clips for Mickey, smoother animation, and a full Redbook CD soundtrack. The final boss also had to be fought twice to truly defeat him in the Sega CD version.
• Mortal Kombat - The Mega CD version features the full arcade soundtrack with remixes of the MK Movie soundtracks, more graphical details (Including blood, heads, and bodies in the pit stage), an FMV intro derived from the original MK TV commercial and a bizarre cheat which renamed the fighters as characters from the BBC TV comedy series Dad's Army (Known as the "Dads Cheat").
• NBA Jam - The most complete port of the arcade game, the title features an FMV ending, as well as the full arcade CD soundtrack. Game data is stored via the Sega CD's internal memory backup.
• Pitfall: The Mayan Adventure - A direct port of the Mega Drive/Genesis game, with FMV intro and a CD soundtrack.
• Prince of Persia - Includes anime-styled FMV sequences, a full CD soundtrack, and the ability to save your progress via internal memory, as well as the option to increase or decrease the games speed/framerate.
• Streets of Rage - appeared as part of the Sega Classics Arcade Collection.
• Wolfchild - Some differences (better than the original Mega Drive version) to the level design and a new CD quality Soundtrack.

References

External links

Sega portal

• Sega-16 - Comprehensive site with hundreds of reviews and articles.
• SegaBase - Comprehensive history of this system
• Sega-Mega-CD-Library - Collectors Guide for SEGA Mega-CD games and stuff