Order of the Butterfly
Posts: 371 from 2003/3/28
Quote:
Kronos wrote:
I'd say verifying a new CPU is easier than any big SW project.
Both of which will come with plenty bugs and exploits often only found decades later even if developed by "professionals".
I once heard testing a CPU is like building software, but you are only allowed to compile once every 3 months and it costs a $1 million each time. That was a LONG time ago and costs have gone up exponentially since then.
Testing a new CPU now is horrifically expensive.
You need to build a model first to test how well it's going to work. An emulator basically, probably just testing the logic at first then moving to a cycle accurate model.
Then you need to design it, and make sure it matches the model. You'll need to simulate it. By that I mean you have to have a cycle accurate model of all the gates, busses clocks etc.
That requires an immense level of computing power, it typically requires a supercomputer. Even then it's simulating at thousands to millions of times slower than the real thing.
Once you know it (mostly) works you can turn it into a bitfile and put it into FPGAs. You need top end FPGAs and lots of them in a system designed for this. These things are probably in the millions these days but they only run hundreds of time slower than the real thing.
Ultimately, the real test is to build a test chip. On the latest processes that's $50s million.
