[exmadscientist]

FPGAs aren't state machines or processors. Not inherently, anyway, even if you can build those things out of them or if they sometimes are sold co-packaged.

And their internal architecture is pretty well documented. See, for example, the Spartan-6 slices: https://www.xilinx.com/support/documentation/user_guides/ug3...

What's less well documented, at least publicly, is the routing, but on some level that's less interesting since it's "just" how you get the electrons from point A to point B, not about choosing A or B. But even the routing is decently well described, though you have to look in some fairly obscure places (like the device floorplan viewer).

I'm not sure why you think FPGAs emulating ASICs is a "waste of potential". By definition, ASICs are strictly more capable and more powerful than FPGAs, so you're climbing up the potential ladder, not down!

[ncmncm]

Why? Because ASICs do one thing from the first time they are powered up until they are finally ground up into sand. But an FPGA could, if programmed right, do completely different things from one millisecond to the next. Their ability to do that is never exploited because our tooling is still much too primitive, and current devices' internal connectivity probably can't route signals to the places needed.

If you think an FPGA is not inherently and necessarily a state machine, no matter how it is programmed (provided power and clock are in specified bounds), that only means you don't know what a state machine is. All clocked digital devices are state machines, and can never be anything other than state machines.

(There is an argument to be made that an FPGA is, itself, an ASIC: an IC whose Specific Application is to be an FPGA. But such an argument would be transparent sophistry.)

[exmadscientist]

There's also plenty of unclocked stuff in the FPGA... like the LUTs that do all the work. There's enough of this and it's important enough that I believe thinking of FPGAs as "just state machines" is dumb. But then I also believe that digital electronics are not "just digital circuits", but better thought of as "bistable analog circuits", so what do I know....

[ncmncm]

If the results of the LUTs don't end up clocked into a register, where do they go?

Of course everything is analog, and ultimately quantum-electrodynamic, but the languages FPGAs are programmed in don't provide access to those domains.