I would have loved too see in the article how the ZPU is extended with an instruction doing 64-bit multiplication and how that measuably improved the performanc

I would have loved too see in the article how the ZPU is extended with an instruction doing 64-bit multiplication and how that measuably improved the performance of the game. It would have been a good example of how a soft CPU core can be adapted to the application. And how hard it would be. In this case probably getting the compiler to emit the new instruction. (The HW part is very simple.)