Sega CD

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The Sega CD is an addon device for the Sega Genesis that will allow the user to both play audio CDs and specially designed game CDs. It also has CD+G capabilities.

The development of the Sega CD was top secret; game programmers didn't know what they were designing for until the Sega CD was finally revealed at Tokyo Toy Show in Japan. The Sega CD was desgined to be in competition with the Turbografx-16, which had a CD module, not the Super Nintendo Entertainment System. The Sega CD was first released in Japan in 1991 where it was dubbed the "Mega-CD." Initially, it was a great sucess becuase of the inherent advantages of CDs and the fact that it had a nice RPG base.

The Sega CD was first released in the U.S in November 1992 for $299. Several titles were avaliable at launch including the controvesial Night Trap.

There is a hookup spot on the side of the Genesis that allows you to hook-up the Sega CD. A total of 149 games have been released for the Sega CD in the U.S. The most popular place to rent Sega CDs was Blockbuster Video, but it was mostly discontinued from 1995-1996.

The Sega CD exists in the following models: Sega CD I (Mega CD I in Japan), Sega CD II (Mega CD II in Japan), JVC X Eye (Wondermega), Sega CDX, LaserActive (Pioneer) Sega CD module.

What it adds to the Genesis:

  - 10 extra sound channels to complement the sound from the Genesis
    Z80 sound processor.
- sprite enhancement features such as scaling and rotation, similar to that of the SNES Mode 7.


Main CPU: Motorola 68000 @ 12.5 MHz

  * Same as the Genesis... runs with it... except the Genesis
CPU runs at the slower clock speed: 7.9 MHz

Graphics Processor: Custom ASIC

  * 6 Mbit Main RAM
* 512 Kbit PCM Waveform Memory
* 128 Kbit CD-ROM data cache memory
* 64 Kbit Internal Backup RAM


  * Originally 64, same as Genesis
* Using programming tricks, can get 128 colors via HAM "Hold and
* Using Cinepak and TruVideo:
- 128 to 256 colors
- Increase screen size from 1/4 to full
- Advanced compression scheme
- Software-based upgrade

Storage capability

  * Approximately 500 MB of data (62 min of audio data equivalent)
* 1/4 screen B/W footage video: 1.5 to 4 hours
* 1/4 screen color footage: 45 minutes
* Above specs are prior to compression

Transfer rate of Sega CD: 150 kbytes/sec (1X)
Boot ROM:

  * 1 Mb contains:
- CD Game Bios
- CD Player Software
- CD+G Software

  Bios Version     Machine
1.00 Original Mega CD
1.10 Original Sega CD, Motorized Drive
2.00 Sega CD2/Mega CD2
2.05 Sega CD2
2.10 Sega CD2
2.21 Sega CDX

Access time: 800 ms
Sound Circuitry:

  * PCM Sound
- Stereo: 8 channels
* 32 KHz Maximum sampling wavelength
* 16 Bit D/A converter
* 8X internal over-sampling digital filter


  * Frequency Range: 20Hz - 20 KHz
* Signal-to-Noise Ratio: >900dB @ 1K
* Channel Separation: >900 dB

Output: RCA Pin Jack x2 (L/R)
Dimensions: 301mm x 212.5 x 112.5
Weight: 3.1 lbs