Pins? On one chip?
How about a 32-bit wide DPM running at CPU speed? There's no way you're going to beat that.
Exactly. That's why they had to use an existing serial bus.
I don't know of any cases of serial busses being used to communicate between sections of a single chip.
If we could get an ARM+FPGA+Gbit ethernet on one chip, we'd buy it right now.
John