[sweden]

This is a very well formulated question, well asked.

People are already doing every step you mentioned but there are three problems:

- Processors nowadays are so advanced and complex that you can't simply approach them as if it was one single block. You need to divide the processor into smaller blocks, develop those smaller blocks and put them together by the end of the development. Like in any engineering problem. The main problem is that it takes a lot of time for all sub blocks to be mature and stable enough for top level integration.

- Once you have all your blocks ready, you can start integration and bring up the system with FPGAs. But now you face the problem that FPGAs are really slow and are not really usable as a normal system. You can run some preliminary tests, the short ones but it would take months to properly execute a normal benchmark.

- You could create and tape out test chips but then you would also need to create all the infrastructure needed for the processor to work like the memory system, memory RAM, communication buses, firmware and etc.