The Dragon 64, launched in 83, was exactly the same computer as the Dragon 32, except that it had 64k RAM instead of 32k, an OS9 operating system and a RS232C connector.
The Extended Basic has been modified to provide RS232 I/O calls, to remove the USR bug present in the Dragon 32 ROM and to add calls allowing the additional interpreter to be invoked.
This second interpreter was the same Extended Basic re-compiled to run from a higher memory address and stored in a EPROM. When invoked, the machine was switched into 64k RAM mode and the interpreter copied from EPROM to RAM giving an extra 16K BASIC workspace. (Source : Jon's Dragon Home Page)
The Dragon 64 was sold in various European countries. A slightly modified version was also manufactured and sold in the US by TANO (Technical Associates of New Orleans) from August 1983. They sold the machine under the TANO name for a few months but couldn't compete with the agressive price policy from Commodore, Atari and T.I. All the unsold machine were eventually sold off to a discount store called California Digital.
In 85 Eurohard, a spanish manufacturer, acquired Dragons Data. Then the Dragon 200 replaced the 64 with some minor changes: power-on lights, auto-repeat keyboard... They also also had plans for a 128k Dragon and a MSX Dragon.