Is used, but I'm not exactly sure what the difference is at the moment. The boot process is effected by which one 'SEGABOOTDISC ', 'SEGADATADISC ', or 'SEGADISCSYSTEM '. The BIOS expects to find one of the following 16byte identifiers at the very beginning of the CD: 'SEGADISC ', I put together a little document on this chip, get it here So you need to multiply the addresses listed in the datasheet by 2 and add $FF0001 to get the coresponding Sega CD address. Since the chip is an 8-bit device, it's mapped only to odd addresses starting at $FF0001. The scale on the waveform graph doesn't correspond to the binary data that produces the waveform in a logical way.
The PCM chip is clocked at ~12.5MHz despite the fact that the datasheet lists 10MHz as the max.
AMERICAN SEGA CD BIOS PDF
You can get the datasheet in PDF format here
If you have trouble compiling it, feel free to e-mail me.įor an explanation as to what SLO is supposed to do, go to the SLO page.Ĭharles MacDonald managed to find the datasheet for a functionally equivalent PCM chip to the one used in the Sega CD. The first file contains the source for the main CPU and the second is an ISO-9660 library which runs on the sub CPU. If someone wants to give it a pretty GUI I'd be more than happy to send them the source. It's text based and has a couple of limitations (biggest of whichīeing that you can't use spaces. This is a little tool that will insert boot code into an ISO and build the data structure described below. Part V: Subroutines, Exceptions and the Stack Part III: Addition, Subtraction and Two's Complement If you have any questions feel free to e-mail me at Assembly Although there is fairly adequate documentationįor the Genesis/MegaDrive there is very little available for the Sega CD/Mega CD and certainly not enough to write any software for it. The goal of this page is to provide the Sega development community with documentation on the Sega CD. Sega CD Development Sega CD Development Home Sega CD SLO 32X Transfer ConvSCD
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