David
Participant
Post count: 22

The .atari800.cfg file is located at /home/pi

Just to confirm, the raspbian version of atari800 should get copied to:
/opt/retropie/emulators/atari800-3.0.0/installdir/bin

Make sure the ownership of atari800 is 7777.

I am not familiar with ATR extensions. Are those Atari 800 system files? I am using it to run 5200 games.