Sega Mega-CD

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Fast facts on Sega Mega-CD
Manufacturer: Sega
Release Date RRP Code
Sega Mega-CD
¥49,800 ?
Sega Mega-CD
$299.99 Media:GamePro US 036.pdf[1] ?
Sega Mega-CD
530DM ?
Sega Mega-CD
?Ptas ?
Sega Mega-CD
1,990FF ?
Sega Mega-CD
Sega Mega-CD
KR3,495 ?
Sega Mega-CD
£269.99 Media:CVG UK 138.pdf[2] ?
Sega Mega-CD
$ ?
Sega Mega-CD
$? ?
Sega Mega-CD
₩398,000 SPC200CR
Sega Mega-CD
NT$ ?

The Sega Mega-CD (メガCD), known as the Sega CD in North America and Brazil, and CD Aladdin Boy (CD 알라딘 보이) in South Korea, is a hardware add-on developed by Sega for the Sega Mega Drive. As the names suggest, it allows a Mega Drive to run compact discs, be it proprietary Mega-CD software, audio CDs or CD+G discs. It also acts as an upgrade to the Mega Drive hardware, sporting an extra processor and extra RAM. The Mega-CD was first released in 1991 and was supported alongside regular Mega Drive cartridges.


The Mega-CD comes in many forms, but in all cases the hardware adds the capability of reading compact discs, technology which in the late 1980s and early 1990s, was becoming a more affordable storage option than the traditional video game ROM cartridge of previous console generations.

A traditional Mega-CD does not act as a stand-alone unit, and needs to be hooked up to a Mega Drive via the expansion port located on the right hand side of the console. Mega-CDs do, however, require their own AC adaptor, meaning that in order to play Mega-CD games, two sockets will be occupied by the upgraded console.

Though one would expect the Mega-CD to simply give the Mega Drive access to compact discs, it in fact adds extra processors, memory and audio features as well, all of which can only be utilised by CD software. The Mega-CD does not, however, solve the issue of graphics, which aside from the ability to scale and rotate sprites on the fly, remain identical to the standard Mega Drive system.

The Mega-CD also offers stereo sound RCA connectors. The Mega Drive on its own will output a monaural audio signal to the television, with stereo only being available through the headphone port located at the front of the console. An external connection from the Mega Drive to the Mega-CD will allow all games to play through the television in stereo.

The Mega-CD can be used in conjunction with a Sega 32X to run one of the six Sega Mega-CD 32X games. Alternatively it can be used to just play regular 5-inch or 3-inch audio CDs.


Main article: Mega-CD consoles.

Like the Mega Drive, there were two major revisions of the add-on by Sega and several special combination units.


The original Mega-CD utilises a CD tray, and sits underneath the Mega Drive (or Mega Drive 2). It is a reasonably large add-on designed to be permanently attached to the console at all times.

Mega-CD 2

A cost-reduced model of the Mega-CD was produced and released around the same period as the cost-reduced Mega Drive 2. This version sits on the right hand side of the Mega Drive, though continues to act as a new base for the console, and is a top-loading device. Fewer mechanical parts means less is likely to go wrong with a Mega-CD 2, and is designed to look sleeker and more appealing. The Mega-CD 2 is designed primarily with the Mega Drive 2 in mind, however a plastic extension piece was included to add extra support with an original Mega Drive attached.

Mega Drive combos: JVC Wondermega/X'eye, Pioneer LaserActive, Sega Multi-Mega, and Aiwa Mega CD

Main articles: Wondermega, LaserActive, Sega Multi-Mega, Aiwa Mega CD.

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.

Development systems

A SNASM Mega CD development unit.

Cross Products SNASM Mega CD

The SNASM Mega CD is a fully featured debugging system developed by Cross Products and officially licensed by Sega for Mega-CD debugging and development. Its features include a debugging interface through a port on the rear of the system as well as CD-ROM emulation through a proprietary SCSI card. The system contains a modified boot-rom which includes all used region combinations for localized debugging. Also available to developers are a number of controls for both the main and sub 68000 CPUs in the Mega-CD. The SNASM Mega CD is used with the SNASM2 family of development programs and Cross Products's SN Server.

Psygnosis PsyQ Mega CD SDK

Psygnosis, a prominent 3rd party developer, developed their own tools for use with the systems which they developed for, including the Mega-CD. The PsyQ development software includes the popular ASM68K and can be used with the Cross Products Mega CD.

Technical specifications

See Sega Mega Drive technical specifications.

The following are upgrades over the Sega Mega Drive technical specifications.


  • Main CPU: Motorola 68000 16-bit processor running at 12.5 MHz
    • Same as the Mega Drive/Genesis. Acts as a coprocessor along with the Genesis CPU. One must note that the Genesis clock speed is slower (7.67 MHz)
  • Instruction set: 16-bit and 32-bit instructions, 16 registers
  • Instruction performance: 2.19 MIPS


  • Graphics processor: Custom ASIC
  • Number of simultaneous colors on screen: 64 (Using programming tricks, this limit is increased to 128 colors via raster effects)
    • 128 colors can also be displayed on screen using HAM techniques[3]
  • On-screen colors available in Cinepak and TruVideo modes: 128 to 256 colors
  • Video size from 1/4 to full screen
  • Advanced compression scheme
  • Software-based upgrade
  • Sprites/Tilemaps: The Mega-CD features enhancement effects such as scaling and rotation, similar to that of the "Mode 7" effect employed by the Super NES. While Mode 7 only supports the scaling and rotation of tilemap backgrounds, the Sega CD supports the scaling and rotation of both the sprites and the tilemap backgrounds. [4]
  • 3D polygon capabilities:
    • Geometry performance: Up to 3,333 polygons/sec
    • Rendering performance: 960 polygons/sec [5]


The Mega-CD adds 10 sound channels to the 10 provided by the Mega Drive's sound chips.

  • CD Digital Audio
    • 2-channel stereo
    • 44.1 kHz sampling rate
    • 16-bit PCM audio depth
  • Ricoh RF5C164 PCM chip provides 8 sound channels:
    • Sound format: 8-bit sign/magnitude monaural PCM (with "stereo" support by allowing each channel to have different volumes on both left and right channels)
    • Maximum sample rate: 32 kHz
    • PCM audio depth: 16-bit[4]

Other specifications:

  • 16-bit DAC
  • 8x internal over-sampling digital filter
  • Frequency Range: 20 Hz - 20 KHz
  • Signal-to-Noise Ratio: > 90 dB @ 1K
  • Channel Separation: > 90 dB
  • Input: Mixer cable for Genesis Model 1 compatibility.
  • Output: Stereo RCA connectors.



  • 500 MB CD-ROM discs (equivalent to 62 min of audio data)
  • Access time: 800 ms
  • 1/4 screen B/W footage video: 1.5 to 4 hours
  • 1/4 screen color footage: 45 minutes
  • CD-ROM drive transfer rate: 150 Kbytes/s (1x)

(Above specs prior to compression)

Boot ROM

  • Size: 1 Mb (128 KB)
  • Used for games, CD player, CD+G viewing, karaoke (limited to Japanese systems) and regional lockout
  • Region codes: "NA" = North America (NTSC), "EU" = Europe (PAL)
Boot ROM Revisions
Boot ROM Version Machine Download CRC32
0.98 Pioneer LaserActive 0.98 (NA) (info) (88 kB) 8c3e3945
0.98 (Asia) (info) (87 kB) 9f5771d2
1.00 Sega/Mega CD Model 1
Victor WonderMega 1 (Asia)
Sega WonderMega (Asia)
1.00g (Asia, NTSC) (info) (80 kB) 3beb1ac2
1.00l (Asia, NTSC) (info) (84 kB) f18dde5b
1.00o (Asia, NTSC) (info) (80 kB) 1d9756a3
1.00p (Asia, NTSC) (info) (85 kB) 9d2da8f2
1.00s (Asia, NTSC) (info) (84 kB) 79f85384
1.00s (Asia, PAL) (info) (85 kB) 550f30bb
1.00w (Sega WonderMega Bios) (info) (84 kB) d21fe71d
1.00 (NA) (info) (90 kB) e7e3afe2
1.00 (EU) (info) (88 kB) 529ac15a
1.04 Pioneer LaserActive 1.04 (NA) (info) (88 kB) 2ed602d7
1.05 Pioneer LaserActive 1.05 (Asia) (info) (81 kB) b24b919d
1.10 Sega CD Model 1 (minor update) 1.10 (NA) (info) (92 kB) c6d10268
2.00 Sega/Mega CD 2
Victor WonderMega 2 (Asia)
JVC X'Eye (NA)
2.00 (1st NA version) (info) (92 kB) 8af65f58
2.00w (2nd NA version) (info) (92 kB) 9f6f6276
2.00c (Asian version) (info) (85 kB) dd6cc972
2.00 (1st EU version) (info) (90 kB) 0507b590
2.00w (2nd EU version) (info) (90 kB) 4d5cb8da
2.00 (X'Eye) (info) (86 kB) 290f8e33
2.00 (Wondermega) (info) (173 kB) 2b19972f1
2.11 Sega/Mega CD 2, Aiwa CSD G1M (Japan) 2.11w (NA) (info) (93 kB) 2e49d72c
2.11c (JP) (info) (86 kB) 12154531
2.21 Sega Multimega (Europe & Japan), CDX (North America), Linguaphone Education Gear (Japan) 2.21x (MultiMega, EU) (info) (91 kB) aacb851e
2.21x (CDX) (info) (92 kB) d48c44b5

1 The ZIP file contains two dumps, a "good" dump and a "bad" dump. The "bad" dump has an incorrect HINT vector, but is otherwise identical to the "good" dump. The CRC32 listed here is for the "good" dump.


Dimensions: 301mm x 212.5 x 112.5
Weight: 1.4 kg (3.1 lbs)


Main article: History of the Sega Mega-CD.


List of games

Main article: List of Mega-CD games.

The five games marked with an asterisk(*) were later released in enhanced form, requiring both the Mega-CD and 32X to be played, and taking advantage of the latter's improved graphics (see Sega Mega-CD 32X).

Launch titles


North America

United Kingdom




Promotional material

Print advertisements

Television advertisements


External links


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