SMT techniques (was Re: group buy for homebrew CPUs?)

[Ray Arachelian]

Dave McGuire wrote:
> On Aug 13, 2006, at 3:36 AM, Don wrote:
>> If an FPGA is fair game, then why not just use an
>> emulation?
>
>   This is a very good point, and (personally) I don't have an answer
> for it, so I think it just boils down to personal preference.  I am
> bored to tears with emulators...but an FPGA implementation of a
> classic machine is something that I find very drool-worthy.
>
>   I think it's a matter of the feeling of "fakeness".  The FPGA
> implementation is REAL HARDWARE...Real logic gates implementing an
> architecture, instead of emulation...which is SIMulation.
<Devil'sAdvocateMode>

Except that each one of the logic operations emulated are executed on a
real ALU, using similar devices. 

For example, when you run an AND opcode through an emulator, at some
point, the real CPU running the emulator does run it through a set of
AND gates. 

When you do an ADD, or SUB that ADD or SUB goes through an ALU running a
similar instruction.

When you do a read or store from memory, that read or write goes on a
memory bus, and so on.

So it's not quite simulation.  It also runs on real hardware.  Granted,
the instructions for how to do the emulation are in software, but they
run on real hardware.  You could look at this as being "interpreted" on
a real computer, and "compiled" on an FPGA. 

Sort of. :-)

</Devil'sAdvocateMode>