DSP pendent -how it works?

Hello all,
I have a cnc small mill,which i have made using steppers and mach3.iam quite satisfied with it.now i want to make a small router for my wood carving requirement.
so the USB-DSP pendent(which is being supplied with all Chinese machines) seems good choice.so i will just make the program in artcam(like software) and dump in to the hand pendent using USB.
so i wanted to know how feasible to make one?
does it uses some micro controller?which read the g-code and send step and direction pulses to stepper driver.how does it handle linear and angular interpolations?
how the system(micro controller) read the data from USB.
there there any existing open source project like that.

iam very much interested.
Pls help

Yes i too interested in this project.
mean while i have a router with spoiled DSP,does any one know where i can get spare for that?