Re: Problems running PC Engine/Turbo-CD games even with BIOS
I realize this is 3 years after this post; but if anyone is still struggling to make CD games work, after trying again and again and downloading the syscard3.pce file from different sources, even though MD5 matched on all, just in case some were corrupt...I finally got it to work by placing the syscard3.pce file in the ROMS folder instead of BIOS. Then, in Emulationstation, I clicked on syscard3.pce, which shows up like a game, and it opened the CD interface. Clicked start, and it began gyrating but didn't fully open. Pressed select and start on my controller to back out and THEN was able to play CD games!

BTW, don't know if this fix will work for emu running on Raspberry Pi. I didn't have issues playing CD games on my Pi 3. But this was the only way I could play PC Engine CD games running Retropie with my Linux Mint x86_64 computer.