Second: kernel ROMs. Altirra has an internal kernel that can be used to run Atari software, and thus you can run demos, games, and productivity software without needing any Atari ROM images. However, this kernel is reimplemented from scratch, and has some compatibility problems with software that depends on undocumented entry points or behavior. Therefore, you may want to consider hooking up real kernel ROM images, which will greatly increase Altirra's software compatibility. I'm afraid I can't offer these for download, but if you have downloaded ROM images from your Atari, Altirra uses the same format and filenames as most other popular Atari 8-bit system emulators.