Sega CD

The Sega CD (known as the Mega‐CD outside North America) is an add‑on for the Sega Genesis/Mega Drive released by Sega in the early 1990s. Introduced first in Japan in 1991 and later in North America and Europe, it was designed to extend the life and capabilities of the Genesis by adding CD‑ROM storage, improved audio, and enhanced scaling/rotation effects. Internally, the Sega CD adds a dedicated 16‑bit Motorola 68000 CPU clocked faster than the Genesis main CPU, additional RAM, a custom ASIC for scaling and rotation, and CD‑DA (Red Book) audio playback. While the base video output and primary sprite/tile rendering still come from the Genesis VDP, the Sega CD can stream data and audio from disc and use its ASIC for effects such as pseudo‑3D road rendering, zooming sprites, and cinematic full‑motion video at low resolutions. The system uses single‑speed CD‑ROM media, enabling dramatically larger games compared to cartridges. This allowed for voiced dialogue, Red Book soundtracks, and FMV sequences that became hallmarks of the platform. Notable titles include "Sonic CD", "Lunar: The Silver Star", "Lunar: Eternal Blue", and "Snatcher", which showcased the improved audio and expanded storage. Despite its technical ambitions, the Sega CD faced high hardware cost, long load times relative to cartridges, and a library with many FMV‑driven titles that aged poorly. Commercially it underperformed compared to Sega’s expectations, especially once newer 32‑bit CD consoles arrived. However, it remains historically important as one of the earliest mainstream CD‑ROM console platforms and is remembered fondly for a core set of standout RPGs, platformers, and experimental multimedia games.

audio

Genesis YM2612 FM + PSG via base console; Sega CD adds Ricoh RF5C164 8‑channel PCM, Red Book CD‑DA audio playback, and CD‑ROM XA/ADPCM support depending on title.

cpu

Primary (base): Motorola 68000 @ ~7.67 MHz (Genesis/Mega Drive); Add‑on: Motorola 68000 @ ~12.5 MHz (Sega CD main CPU) plus sub‑CPUs for CD control.

gpu

Video handled by Genesis VDP (same as base console): 64 on‑screen sprites, tiled background layers, hardware scrolling; Sega CD custom ASIC provides scaling/rotation and assistance for FMV and pseudo‑3D effects.

media

Single‑speed CD‑ROM (Sega CD / Mega‑CD discs), typically up to ~650–700 MB; supports CD‑DA audio tracks and data tracks.

ram

Sega CD: 512 KB main program RAM + 256 KB Word RAM (for graphics/data) + 64 KB PCM sound RAM + 8 KB backup RAM for saves; uses Genesis VRAM via base console.

releaseYear

1991 (JP), 1992 (NA), 1993 (EU)

resolution

Uses Genesis VDP modes, commonly 320×224 or 256×224 (up to 320×240/256×240 visible depending on region); FMV often at reduced active area within these resolutions.