I'm interested in the role of the Dragonball - i was under the impression that it couldn't be used as a drop-in replacement for a normal 68k chip due to differences in the instruction set. If this is the case - how have they circumvented that ? If not - then how come no-one has designed an accelerator around one yet?
Dragonball should have good 68k compatibility on the Amiga. I believe the MOVE from SR instructions was made privileged and addressing may need to be 32 bit clean but these have been assumed since an early stage of Amiga development (although programs like M$'s AmigaBasic didn't follow the standards and probably fails). The ISA enhancements should be very compatible (old 68000 software knows nothing about them). The biggest problem with Dragonball is it's weak in performance despite clock speeds up to 66MHz. It's a specialized processor designed for low power consumption. The TG68 fpga CPU is giving 68030 performance at a similar clock speed in the fpga Arcade. The Phoenix fpga CPU may give 10x or more the performance of the 66MHz Dragonball in an affordable fgpa. IMO, Dragonball is not competitive in 68k performance for an accelerator and it's no longer in production. The advantage it has is that it is cheap.
Its an interesting design and although it might not be that nippy its definitely a step forward and the addition of the AGA core makes it a very interesting proposition indeed. (Partly the reason I didnt get an original Minimig was that this was missing).
Most AGA software needs the 68020 ISA. MiniMig was an important step in Amiga fpga development but the next generation Amiga fpga hardware is the way to go for 68020+AGA compatibility, IMO.
