Due to popular demand atari800 emulator with a8cas support was updated to version 5.2.0. Download from Modified atari800 emulator page

MK.Turbo system formerly named as "unk" is now properly named as mkturbo

Added support for variable baud rates for MK.Turbo.

Fixed bug causing data loss during processing of long sequences of raw fsk signals.

Fixed bug causing data loss during processing of stop bit in fsk-encoded recordings.

Added checks for required components (when option --syscheck is used).

Added "MK.Turbo" to the list of supported turbo systems.

Fixed loading of turbo tapes in cases, where loader does not initialize Pokey registers properly. It works on real hardware, so it should work in emulator as well.

 Get it from appropriate download page.