clownacy/clownmdemu-mcd-boot

A minimal Mega CD boot ROM, specifically for use with clownmdemu's Mega CD emulation.

clownmdemu-mcd-boot

A minimal Mega CD boot ROM, specifically for use with clownmdemu's Mega CD emulation.

Building

1. Create a folder called "build".
2. Assemble the "core.asm" file in the "sub" folder to build the Sub CPU BIOS file into the "build" folder.
3. Compress the assembled Sub CPU BIOS file in Kosinski in the "build" folder, using Clownacy's accurate Kosinski compressor (other compressors may not compress it in a way where it can be detected in Mode 1). Make sure that the compressed file is named 'subbios.kos'.
4. Assemble the "core.asm" file in the "main" folder to build the full boot ROM.

Mode 1 Compatibility

It is important that the string 'SEGA' appears at exactly offset 0x6D in the compressed Sub CPU BIOS file. This is because software which uses the Mega CD in 'Mode 1' checks for this string to detect where the Sub CPU BIOS is. If the string is not at the expected position, then software may fail to detect the Mega CD or even crash!