voltage based servo controller ?

Hi all,

I picked up a servo controller today and while trying to find out more
data on how to connect it, I found out is is not a step and direction
based unit, but a voltage control based unit.

There is a pixie interface that is discontinued. the Pixie used to
turn the step and direction into the inputs for this unit.

Anyone know what it was originally used for ? was it the first tyep
of control before step and direction became the rage ?

Dave