Looking for:
Latest PowerPC CPU supported by OS4 for modern performance
plus 68K CPU, but faster than an 68040 and more compatible too (*)
plus AGA, but enhanced, with fallback ECS support too (*)
plus Graphics card included (*)
plus AmigaOS 4.X, able to run natively any 68K or PPC app.
The items marked with (*) can be implemented easily and cheaply via FPGA technology, powered by the Minimig AGA core currently under active development by MikeJ and Yaqubed. Soft core approach also allows for dynamic reconfiguration between 68000 thru 68060, OCS thru AGA and beyond, without reliance on Amiga ASIC custom chips which would be prohibitively expensive to produce and so aren't present on the "Amiga NG" systems.
