Serial port protocol

The suggestion of using a separate microprocessor to do the real time
part of CNC is one I'm interested in. As I've mentioned here, I have a
(IMHO) rather nice front end, but I dont like the 'real time' aspects of
Windows. I have tinkered with a microprocessor on a serial line to get
around this and would like to do more.

I know Flashcut uses such a scheme, and I got into a small flame war
with them on rec.crafts.metalworking a while back over it being a closed
protocol. I object to buying a device that will only work with their
software. I have wanted to put a 'wiretap' on my friends Flashcut and
see just what the protocol looks like, but I just havent done it yet.

Has anyone given thought to such a protocol? Would this group be a forum
to develop it? In the recent note by Matt Shaver he suggests :

>I acknowledge the truth of the above statement ;) Why not give it commands
>like, "G1X2.3875Y4.2946F4..." (just kidding!).

Since we want the real math to be in the PC, how about something very
close to Gcode, but in step counts, not inches. Actually that may be
about the same as HPGL.

I would be much more interested in doing software to drive an
intelligent controller if I was using something a bit common, not my own
unique controller.

So, can we come up with a protocl here?

ron