Dreamcast GDI Compatibility List

[SWAT]

Memory used for the loader. In most cases 0x8c004000 it's normal (also 0x8c000100 works in 50% games). But some games used this area, so need place the loader in another memory.
Emu async need only for PIO mode or DMA with CDI or not optimized GDI (or for SD with any images). It's emulated async reading as true DMA, for more smooth gameplay if the game preload data continuously in gameplay. Lower value - more smooth gameplay, but long loading time and vice versa.
Boot mode in most cases use - Direct. Some games need boot from IP.BIN, but IP.BIN used the same memory as loader, so in this case can help truncated IP.BIN. If you place the loader in another memory, you can use full IP.BIN. But really in most cases works Direct.

CDDA used additional memory for PCM buffer, if you put loader to lower memory, buffer used high memory and vice versa.
If you boot WinCE and use 0x8c000100, in this case PCM buffer will use 0x8c008000 so it's should better compatibility. Also this trick used for ADPCM tracks, because for it need buffer in twice smaller.
In another cases if you put the loader in lower memory (0x8c000100 - 0x8c004800), PCM buffer uses 0x8cfe0000 (because KATANA used some lower memory all time unlike WinCE) and it's can give some problems. If you have problems with CDDA, try put the loader in some high memory, that place the PCM buffer in lower memory and you can play with high memory for search free space for the loader.