I almost forgot this thread. Too much (drunken) fun with the buddies from studying times.
It is relatively easy to check the processor lines' information content, attach a voltage meter to the line to give you an idea. Unfortunately, you cannot do this with normal hand held voltage meters because of the refresh rates and integration times. This is also the reason why I think that any copy protection system will ultimately fail. It is a question of how easy this is to do, and currently it is probably too difficult for your common pirate or geek to handle.
Instead, one could utilize an oscilloscope, but current processors have 32 to 64 lines each of which must be monitored if the information content needs to be decyphered. I doubt you can easily find a digital oscilloscope that could support so many channels, also signal frequencies above 3 GHz (period of 0.3 ns - still doable) might make it difficult for the oscilloscope. Instead of that, one can use logic analyzers that don't bother with the accurate voltage sampling, the only thing which matters is whether the voltage is up or not. This way, the sampling frequency might get much higher so that 3 GHz is quite easy.
But the real problem is, according to my understanding, that the 8086 processors are still quite nice to teach students what is actually going on in the computer. With 8086 you can nicely follow the flow instructions to the processor, and processor answering them each on their own turn, in Assembly controlled loops for an example. Newer processors (since 80386 IIRC) have some kind of internal system, some of the assignments are returned earlier and some of the later, but the system keeps track of the assignment numbers so that the rest of the computer sees nothing special in the data. Even though the processor computed them in a totally different order. It is relatively difficult to follow that kind of data flow.
For the programmers:
How did you actually think that the processor testing would happen, if you couldn't follow the data flow physically?
Mika