That's what's confusing me, I've been able to play Atari atr games fine.. Keystone Capers is working here?Yeah for sure. Get the BIOS files both in your Tarimsu and Aroma retroarch folders. Then do a search online and look for Atari games in .atr format. Those are Arari 5 and a 1/4 inch floppy disks. I like to play Keystone Capers
I thought there was some special mode where you were booting into the Bios or something but yea, games seem to be working ok for me.
Make sure your Bios are 100% correct, I had issues with the 5200 Core initially until I realised the Bios, although RA says were correct were bad.