An add-on that bolted under the Genesis, the Sega CD added a CD-ROM drive, a second 68000, extra RAM, and a graphics ASIC for scaling and rotation. It opened the door to CD audio and full-motion-video games — and to the moral panic over titles like Night Trap.
The Four Natures
each piece emerges by one of four natures
The Idea
the three-beat story
The Sega CD is a base the Genesis sits on. It contributes its own Motorola 68000 at 12.5 MHz, more RAM, and a CD-ROM drive — effectively doubling the system's processing while sharing the Genesis's video output.
A custom chip added hardware scaling and rotation of graphics — Mode-7-style effects the Genesis lacked — used for pseudo-3D racers and flashy intros.
CD capacity enabled grainy full-motion-video games — live-action footage as gameplay. Night Trap and its kin drew US Senate hearings and helped spur the creation of game ratings.
The Teardown — Click a Block
the machine, laid out as a block diagram — the main processor on top, the rest of the silicon beneath, buses showing what talks to what. Click any block to read its spec. An accurate architecture diagram (a teardown illustration, not a schematic).
The Spec Sheet
the headline numbers — the spec edition
12.5 MHz (second 68000).
hardware scaling + rotation.
atop the Genesis.
CD audio + FMV.
sits beneath it.
The Reckoning
the teardown, and the honesty about it
The Domain: Open It and Spec It
the teardown
- EXEREÚNESIS takes a real, made machine apart down to the chip and writes the honest spec — not a story-world but a technical anatomy.
- >One of a growing series of console teardowns; siblings link from the marquee.
Two-Layer Honest
datasheet vs lore
- Settled: the second 68000, the scaling/rotation ASIC, the added RAM, and the CD-ROM are documented.
- Flagged: the FMV-game moral panic (Night Trap, the 1993 US Senate hearings) is real history and led to the ESRB — stated as documented events, not sensationalised.
Render, Not Invent
sourced
- Summarized from the public technical record for the SEGA CD · MEGA-CD; the manufacturer and its engineers are cited, not minted.
- No ROMs, BIOS, or copyrighted code are reproduced. Emergents are physical components; the block diagram is an illustration, not a schematic.
The Roster
every chip and part as an ACI .agent — each a birth certificate & a nature (6)
