XRoar is a Dragon 32/64 and Tandy Color Computer 2 emulator. It runs exaclty like the original computer. It presently supports cassette images or virtual disks. The emulator requires the original Dragon 32, Dragon 64 or CoCo 2 ROMs.
Debian snapshot builds are available in the Apt repository.
Ubuntu snapshot builds are available in this PPA on Launchpad.