1991 · Sega · Japan · console
Sega CD / Mega-CD
An ambitious CD-ROM add-on that bolted onto the bottom or side of the Genesis.
Essential Easy to run ▶ Watch on YouTube ↗
An ambitious CD-ROM add-on that bolted onto the bottom or side of the Genesis. While infamous for its low-resolution full-motion video (FMV) games like Night Trap, its top-tier JRPGs and platformers with CD soundtracks are extraordinary.
Sonic CD introduced Amy Rose and Metal Sonic, featuring dynamic past/present/future time-travel level variations and two completely different CD soundtracks (Japanese/European Spencer Nilsen vs. US funk rock).
Under the hood
- CPU
- Secondary Motorola 68000 @ 12.5 MHz (Runs in parallel with Genesis 68000!) + Ricoh ASIC scaling chip
- Sound chip
- Ricoh RF5C164 (8 channels of 16-bit PCM audio) + CD-DA Redbook Audio tracks
- Graphics
- Hardware sprite rotation, scaling, and bitmap zooming processor
- Media
- 500 MB CD-ROM optical discs
What it cost
about 16% of a month’s pay in 1991 · about $689 today
| US Sega CD add-on launch price ($299 with Sol-Feace & Sherlock Holmes) |
$299 (1991)
CD-ROM add-on with custom ASIC hardware scaling and rotation. |
|---|---|
| Typical street price | — No verified mass-market street price recorded yet. |
| Units sold | ≈2,240,000 estimate 2.24 million units sold worldwide. |
Why it mattered
Sonic CD introduced Amy Rose and Metal Sonic, featuring dynamic past/present/future time-travel level variations and two completely different CD soundtracks (Japanese/European Spencer Nilsen vs. US funk rock).
Emulating it today
| Emulators | Genesis Plus GX, Kega Fusion |
|---|---|
| Setup effort | Easy to run (2.5 on this site's scale) |
| Controls | A standard modern controller covers the ordinary controls, though unusual accessories may need custom mapping. |
| Runs on a handheld | Yes |
Requires Sega CD BIOS files (`bios_CD_U.bin`, `bios_CD_E.bin`, `bios_CD_J.bin`) in the RetroArch BIOS folder. Runs with zero load times on Genesis Plus GX. The emulator names above are starting points, not a promise that every title or accessory behaves identically. Computer platforms usually add model selection, disk handling and keyboard setup even when CPU emulation itself is mature.
Sega CD / Mega-CD BIOS (bios_CD_U.bin, bios_CD_E.bin, bios_CD_J.bin)
The Sega CD add-on contains a 128 KB BIOS ROM that runs on its auxiliary 12.5 MHz 68000 processor. The BIOS handles CD drive communications, disc track seeking, rotation/scaling ASIC hardware calls, and the spinning logo boot screen. Emulators like Genesis Plus GX cannot boot CD images without it.
How many files you need: 1. One 128 KB BIOS file matching the region of your discs (bios_CD_U.bin for US, bios_CD_E.bin for Europe, bios_CD_J.bin for Japan).
Where it stands legally: Copyrighted by Sega; must be dumped from a physical Sega CD unit.
Firmware details checked 2026-08. Emulator requirements change — see Libretro — Genesis Plus GX documentation for the current list.
Where the software is
Preservation catalogues describe verified dumps; they do not grant permission to download commercial software. A curated, correctly matched set is easier to use than an undifferentiated archive.
Copyright: Commercial software remains copyrighted unless its owner explicitly released or relicensed it. Homebrew, public-domain programs and current reissues should be treated separately from abandoned commercial titles.
This site names preservation projects and explains what they are. It does not link to ROM downloads.
Where to start
- Sonic CD Platformer
Time travel through Past, Present, Good Future, and Bad Future with CD-quality animation and music.
- Snatcher (Sega CD) Cyberpunk Graphic Adventure
The only English-translated release of Hideo Kojima’s cyberpunk classic with exceptional voice acting.
- Lunar: Silver Star Story & Lunar: Eternal Blue JRPG
Studio Alex & Game Arts’ emotionally sweeping fantasy RPG with animated anime cutscenes.
- Popful Mail: Magical Fantasy Adventure Action Platformer RPG
Charming, fast-paced comedic anime side-scroller with stellar Working Designs translation.
- Shining Force CD Strategy RPG
Combines the Game Gear Gaiden games with enhanced graphics, CD audio, and new story chapters.
- Silpheed 3D Space Shooter
Pre-rendered polygon 3D space battles with real-time tactical wingman radio chatter.
- Final Fight CD Beat 'em up
Restores Guy, 2-player co-op, and adds a full arranged CD rock soundtrack.
The verdict
Hardware scaling/rotation processor and Redbook CD-quality audio. Home to the definitive Sonic CD, Snatcher, Lunar: Silver Star Story, and Popful Mail.
The strongest software can be rewarding, but original controls and setup assumptions may matter more than screenshots suggest.
- Worth it if
- Players curious about sega home consoles and willing to learn how the original machine worked.
- Not for
- Anyone who wants a large, instantly accessible library and no model, firmware or control decisions.
Scored 4/5 for fun today and 5/5 for historical importance. Those two scores decide the label at the top — a machine can matter enormously and still be no fun.
Read more & watch
This page is 50% complete against the facts we try to record for every system. Gaps are shown as gaps.