It could be good to use the same ISA for the coprocessor as for the main CPU, worked well for IBM mainframes. Smarter Ethernet NICs often contain a CPU to do t

It could be good to use the same ISA for the coprocessor as for the main CPU, worked well for IBM mainframes. Smarter Ethernet NICs often contain a CPU to do things like TCP offload, the "microcode" for them can be just machine code for this CPU, having a more open architecture for the peripheral devices would make it easier to add support for more network protocols.