Assembly language instructions implementation

Question

Is there some information source or technical draft (something like RFC for networking) describing implementation of particular instructions (e.g. mov, jmp, je, jle, inc, ...) for Intel architecture?

Some general talk is on wikipedia but I'd like to know perfectly what's happening under the hood.

Thank you

Answer 1

They are generally implemented with micro-code, you can read up on that here, it mostly depends on the type of processors you are looking into (embedded, multi-core, power saving etc), Intel has some architecture design details here (the rest of the manuals also have various more minor details).

Its a bit old school now, but you should also find this helpful and interesting, it details the in depth design of the Pentium 4 series of processors, including instruction set implementation.

Answer 2

The implementations of many (most?) instructions have changed substantially over time. You could look at (for one example) Agner Fog's web site for some information, but be aware that:

1. a lot of it is at least partially guesswork
2. some of it is clearly out of date
3. Some of it varies between current processors (especially Intel vs. AMD).

Answer 3

You can download the x86 manuals from Intel here.