Sega Mega-CD/Technical specifications

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Back to: Sega Mega-CD.

Technical specifications for the Sega Mega-CD.

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

See Sega Mega Drive technical specifications for details of the base Mega Drive hardware

CPU

  • Main CPU: Motorola 68000 16-bit processor running at 12.5 MHz
  • Same as the Mega Drive. Acts as a co-processor along with the Mega Drive CPU.
  • Bus width: 16-bit
  • Instruction set: 16-bit and 32-bit instructions, 16 registers
  • Performance: 2.19 MIPS
  • Co-processor: Motorola 68000 (Mega Drive CPU) running at 7.67 MHz
  • Bus width: 16-bit
  • Performance: 1.34225 MIPS

Graphics

  • Bus width: 32-bit (2x 16-bit)
  • Bus clock rate: 6.25 MHz (25 MB/s bandwidth)
  • Transformed graphics tiles are DMA'd to the main VRAM for display.
  • Full motion video: Video size from 1/4 to full screen, advanced compression scheme, software-based upgrade
  • On-screen colors available in Cinepak and TruVideo modes: 128–256 colors
  • Sprites/Tilemaps: The Mega-CD features enhancement effects such as scaling and rotation, similar to Sega's Super Scaler arcade hardware and 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.[2]
  • DMA transfer rates: 3.467179 MB/s (VRAM), 6.934358 MB/s (CRAM/VSRAM)
  • Transfer rates during active display: 1.625 MB/s (VRAM), 3.25 MB/s (CRAM/VSRAM)
  • Read/Write fillrate: 6.934358 MPixels/s
  • Write fillrate during active display: 3.25 MPixels/s

Audio

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
  • 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[2]
  • Bus width: 8-bit

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 Mega Drive Model 1 compatibility.
  • Output: Stereo RCA connectors.

Memory

  • Main RAM: 4 Mbit (512 KB)
  • VRAM: 2 Mbit (256 KB)
  • PCM audio samples: 512 Kbit (64 KB)
  • CD-ROM data cache: 128 Kbit (16 KB)
  • Internal Backup RAM: 64 Kbit (8 KB)
  • System Boot ROM: 1 Mbit (128 KB)
  • External Memory Card: 1 Mbit (128 KB) CD BackUp RAM Cart
  • System RAM bandwidth: 62.5 MB/sec (3 buses, 56-bit bus width)[4]
  • Main RAM: 25 MB/sec (16-bit, 12.5 MHz, FPM DRAM)[5]
  • VRAM: 25 MB/sec (32-bit, 6.25 MHz, PSRAM)[6]
  • Audio RAM: 12.5 MB/sec (8-bit, 12.5 MHz, SRAM)[7]

Storage

  • 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

Main article: Sega Mega-CD/Boot ROM.
  • Size: 1 Mb (128 KB)
  • Used for games, CD player, CD+G viewing, karaoke (limited to Japanese systems) and regional lockout

Other

  • Dimensions: 301 mm (11.85") x 212.5 mm (8.366") x 112.5 mm (4.429")
  • Mass: 1.4 kg (3lb 1.384oz)

Notes

References


Sega Mega-CD
Topics Technical specifications | History | Magazine articles | Promotional material
Hardware Mega CD (Asia | North America | Western Europe | Eastern Europe | South America | Australasia | Africa)
Sega Multi-Mega (Asia | North America | Europe | South America | Australasia)
Wondermega | LaserActive | CSD-G1M
Misc. hardware CD BackUp RAM Cart | Mega-CD Karaoke | Pro CDX
Development tools SNASM Mega-CD | PsyQ Mega-CD SDK | PSY-Q CD Emulation System (Mega-CD)
Unreleased hardware Game Genie