This page has only information and files concerning the Sega CD directly - if you are looking for processor documentation, assemblers or general tools, please have a look at the Genesis development page.

   In addition to the documentation available on this page, I also have the official hardware documentation of the Sega CD at hand. If you are interested in obtaining it, please contact me via email.

 

Downloads

   
 

	File description
	European Mega CD model 1 BIOS RECOMMENDED Version 1.00, October 1992 (EPROM dump, recommended for emulators)
	European Mega CD model 2 BIOS Version 2.00, March 1993 (EPROM dump, suitable for emulators)
	European Mega CD model 2 BIOS Version 2.00, June 1993 (EPROM dump, suitable for emulators)
	Japanese Mega CD model 1 BIOS Version 1.00, November 1991 (EPROM dump, suitable for emulators)
	Japanese Mega CD model 1 BIOS RECOMMENDED Version 1.00, December 1991 (EPROM dump, recommended for emulators)
	American Mega CD model 1 BIOS RECOMMENDED Version 1.10, October 1992 (EPROM dump, recommended for emulators)
	American Mega CD model 2 BIOS NEW Version 2.00, March 1993 (EPROM dump, suitable for emulators)
	American Mega CD model 2 BIOS Version 2.00, June 1993 (EPROM dump, suitable for emulators)
	decompressed Sega CD 68k BIOS (size: 1 mbit) This is the BIOS data which is decompressed by the Genesis 68k into the Sega CD 68k RAM (based on Sega CD BIOS 1.10. Not suitable for emulator usage, just suitable for programming purposes.
	8KB Backup cartridge (empty) This is the dump of one of the battery-backep up savegame cartridges which were used like memory cards to save additional savegames. This version is formatted, i.e. totally empty.
	8KB Backup cartridge (with Sonic CD US savegame) This is the the same as above, but with a Sonic CD savegame on it.
	Datel CDX pro v1.8I (size: 0,5 mbit) This cartridge allows it to play import games on certain Sega CD machines. Works only with certain BIOS versions.
	Datasheets... ...of the following Sega CD ICs: LH5P832 (RAM), NJM3403/4A (Amplifier), LC78815M/83K/85KM (sound chip), LC89515K (CD-ROM controller)
	Byteswap Swaps lo/hi bytes of a file (see above).
	Sega Checksummer Tool to compute the Sega-specific checksum of ROMs.
	ISO 9660 A nice description of the ISO 9660 standard which the Sega CD games use.
	Territory lockout Some thoughts on the Sega CD territory lockout, written by Flavio.

 

Sega CD programming FAQ

 
    In this FAQ I try to gather as much information about the hardware and the software structure of the Sega CD as possible. This pool of information will grow steadily. If you have any information which you feel belongs here (maybe you can confirm or deny some of the information which is already given), please contact me.

   These documents (thanks for the tip, Mark! :-) are the US patents for the Sega CD device and for the CD country protection routines. Though these documents are rather non-specific in terms of giving concrete memory addresses of the various functions, they describe the inner workings of the Sega CD very precisely. I have commented the documents where I think it was necessary or helpful. Feel free to mail me your comments or post them on my message board.

   With these two documents it should be a LOT easier to reverse-engineer some games in order to write an emulator, because now you actually KNOW what the various routines of the games are supposed to do according to the patents. 

   For Genesis technical stuff, please visit the Genesis section of my site, you´ll find some useful documents and tools there.