From the NatAmi questions & answers:
"How much can be gained by transferring the FPGA to a custom fixed function chip ?
Oversimplified answer:
A - Medium price FPGA ~ 100-200 MHz
B - Very expensive FPGA ~ 250-500 MHz
C - Custom Chip based on little reworked FPGA code ~ 500 MHz
D - Custom Chip complete redesigned 500 MHz - Several GHz
But creating custom chip (ASIC) does cost a lot of money.
Option C costs some money but less than a million.
Option D is too expensive for the Amiga market.
For the best price/performance mis we target solution (A) for now. "
