Stepper control w/o a computer?????

I'm new to this CNC stuff but I am starting down this road one step
at a time. I am getting a better understanding of CNC each day.
My future plans is to convert my Drill/Mill to CNC.
I would like to know is there a device that will control a stepper
motor with out a computer. ie a black box that will tell the motor
to spin this way spin that way.
I guess this box would have to send step and direction signals?
useing switches.
The reason I ask this is if I did this first I could have a power
feed first then worry about adding computer control later.
plus I could work out all of the mech bugs with out haveing to deal
with computer bugs.
Ideas comments..


Thanks

Jerry