
Sega CD
Technical Specifications
CPU
Motorola 68000 @ 12.5 MHz (secondary processor, supplements Genesis 68000 @ 7.67 MHz)
GPU
Custom ASIC for hardware sprite scaling and rotation, bitmap processing; Sega custom gate array for CD-ROM data decompression and FMV playback
Memory
6 Mbit (768 KB) main program RAM, 512 Kbit (64 KB) PCM waveform memory, 256 Kbit (32 KB) CD-ROM data cache, 128 Kbit (16 KB) word RAM available as 2x 1 Mbit banks
Storage
Internal battery-backed SRAM (8 KB) for game saves, optional RAM cartridge for additional save data
Display
Uses Genesis VDP for primary display output; ASIC adds hardware-assisted scaling, rotation, and 256-color bitmap rendering capabilities overlaid on Genesis output
Audio
Ricoh RF5C164 PCM sound chip, 8 channels at 32 kHz sample rate, 16-bit stereo; CD-DA audio playback; mixes with Genesis YM2612 FM and SN76489 PSG audio
Media
CD-ROM (1x speed, 150 KB/s data transfer rate), supports CD-DA, CD+G, and mixed mode discs
History
Hardware Variants
Mega-CD Model 1 (Japan, HAA-2910)
Released: December 12, 1991
The original Japanese model designed to sit underneath the Mega Drive. Front-loading CD tray with motorized drawer. Cost ?49,800 at launch.
Sega CD Model 1 (North America, MK-4102)
Released: October 15, 1992
The North American version designed to mount to the right side of the Genesis Model 1. Front-loading CD tray. Launched at $299.
Mega-CD II / Sega CD Model 2 (MK-4102A)
Released: April 23, 1993
A smaller, cost-reduced redesign with a top-loading disc mechanism and flip-top lid. Designed to pair with the Genesis Model 2. Launched at $229.
Sega Multi-Mega / CDX (MK-4121)
Released: May 1, 1994
A compact all-in-one device combining Genesis and Sega CD into a portable CD player-sized unit. Also functioned as a standalone music CD player. Very limited production run.
Aiwa Mega-CD (CSD-GM1)
Released: January 1, 1994
A licensed variant by Aiwa that integrated the Mega Drive and Mega-CD into a portable boombox-style unit with built-in speakers and radio.
Development Story

Sonic CD
• 1993

Sonic Megamix 5.0
• 2023

Sonic the Hedgehog Megamix 4.0b
• 2012

Mortal Kombat
• 1993

3 Ninjas Kick Back
• 1994

The Amazing Spider-Man vs. The Kingpin
• 1993

The Secret of Monkey Island
• 1993

Final Fight CD
• 1993

Shining Force CD
• 1994

The Adventures of Batman & Robin
• 1995

Prince of Persia
• 1993

Earthworm Jim: Special Edition
• 1995
About the Sega CD
The Sega CD (SCD) is a home video game console manufactured by Sega. Released on December 12, 1991, it belongs to the 0th generation of gaming hardware.
With a library of 19+ games, the SCD remains one of the most popular platforms for retro gaming enthusiasts. Our wiki provides detailed information about the hardware specifications, variants, and game library to help you understand and appreciate this classic gaming system.
Whether you're researching emulation compatibility, collecting vintage hardware, or simply exploring gaming history, the SCD encyclopedia entry offers comprehensive information about this iconic gaming platform.