Two-axis antenna or telescope pointing can be done by motor-controlled actuators.  Amateur radio operators commonly use the Yaesu G-5400B dual-axis rotor to point their antennas, tracking a satellite across the sky. This rotor's controller box has an 8-pin DIN plug in the back for remote control.  This plug allows you to interface the controller with a computer for automatic control by satellite tracking software.

There are a variety of commercial and kit interfaces for the Yaesu G-5400B (see listing under The Station Program on the satellite tracking software page) and ZL2AMD's UNI_TRAC 2000 universal tracking system for amateur radio satellites. 

I use a "home brew" interface called the "FODtrack" (after its designer whose amateur radio call sign is XQ2FOD). The FODtrack interfaces through the computer's parallel (printer) port.

I built my first FODtrack interface on a perforated board with foil pads on the reverse side.  The completed interface board is shown below.

The finished FODtrack interface was mounted in a metal enclosure.  Light Emitting Diodes (LEDs) were added to show when when the interface is engaged (red LED) and when it's moving the G-5400B left, right, up, or down (green LEDs). The interface in its enclosure is shown below.

The most critical component of the FODtrack interface is its Digital to Analog Converter (DAC). FODtrack uses an Analog Devices AD7528 compatible  DAC.  This IC is somewhat scarce in a Dual In-lin Package (DIP), but readily available in a surface mount package. You can get the AD7528 in a 20 pin DIP from Tech America (part AD7528JN, catalog # 900-6747) or from Marshall Industries (Texas Instruments part TLC7528CN).

You can download the FODtrack interface schematic diagram and basic driver software.

A tracking interface lets the computer command the antenna azimuth and elevation pointing angles

Through the interface, software can have your antennas automatically track satellites across the sky

The FODtrack is an example of an inexpensive tracking interface you can build