step/dir inputs to servo controllers

I have been looking at some servo controllers and have found some
that take step & direction inputs as opposed to the analog control
input. For example:

http://www.logosolinc.com/download/ls-174wp.pdf

It seems that these servo controllers (and the Geckos) could be
driven from a PC with a parallel port. Is this how most hobbiests
put together servo-based CNC systems?

Thanks for help.

Best,
Bob