Program behavior not the same on MegaCD
Posted: Fri May 24, 2013 1:08 pm
Hello,
I want to code for the MegaCD, but didn't succeed in using the classic SGDK, so I started coding a little test program in 100% 68k asm
It works great as a megadrive rom, but when switching to MegaCD, it doesn't work anymore.
First I tried the cdboot example of Chilly Willy, I compiled the program with org $200000, skipping the cartridge header, making an APP.BIN, an iso image with this file in root directory, and replacing the first 32k of iso file with EU_BOOT.BIN
Test in emulator doesn't work, it keep reading the CD after the "sega sonic" animation. (can't find the file ?)
Then I tried this cd boot kit: http://gendev.spritesmind.net/files/mcd ... jectCD.zip
(see viewtopic.php?t=872 )
Now, I have the program loading and booting, but while transferring the Tile data to vram, it seems that the program stop working during the transfer and jump in random position (!?)
I can see in the debugger of the emulator that my palette is set correctly, and that a partial amount of tile have been transfered, but not the entire tile data.
The same code works perfectly on megadrive as a rom cartridge !
so, can anyone help me about this strange behavior ? Did I miss to do something specifically related to megacd ?
Thank you
I want to code for the MegaCD, but didn't succeed in using the classic SGDK, so I started coding a little test program in 100% 68k asm
It works great as a megadrive rom, but when switching to MegaCD, it doesn't work anymore.
First I tried the cdboot example of Chilly Willy, I compiled the program with org $200000, skipping the cartridge header, making an APP.BIN, an iso image with this file in root directory, and replacing the first 32k of iso file with EU_BOOT.BIN
Test in emulator doesn't work, it keep reading the CD after the "sega sonic" animation. (can't find the file ?)
Then I tried this cd boot kit: http://gendev.spritesmind.net/files/mcd ... jectCD.zip
(see viewtopic.php?t=872 )
Now, I have the program loading and booting, but while transferring the Tile data to vram, it seems that the program stop working during the transfer and jump in random position (!?)
I can see in the debugger of the emulator that my palette is set correctly, and that a partial amount of tile have been transfered, but not the entire tile data.
The same code works perfectly on megadrive as a rom cartridge !
so, can anyone help me about this strange behavior ? Did I miss to do something specifically related to megacd ?
Thank you