Nova for Windows controls antennas through a wide variety of interfaces.  
The current list is presented below.

Name Description/comments Source
LabJack U-12 12 bit, USB,
terrific value, but limited availability
LabJack Corporation
Kansas City Tracker 8 bit internal ISA card AMSAT
PrimeSat USB, autotracking & radio control PrimeTec
SASI Sat Tracker 8 bit external parallel port no longer available
Uni_Trac 8 bit external parallel port
Antenna control AND radio tuning
with Nova for Windows
David Lamont
New Zealand
ARS/RCI 8- or 12-bit external parallel port antenna control interface and software from EA4TX Pablo Garcia, Spain
AEA ST-1 8 bit external parallel port no longer available
RIF-PC 10 bit internal or external Orbit Electronics, Germany
M2 RC-2800P external, serial interface,
0.1 precision
M2 Antenna Systems
TrakBox/RAC 805 external, serial interface,
host mode
Creative Designs, Japan
FOD-Track simple external,
parallel interface
EasyComm serial, output only documentation
NovaComm I serial, output only in NfW's Help file
DDE Dynamic Data Exchange documentation, examples in C++,
Visual Basic and Delphi, and Perl
Yaesu GS-232A 10-bit A/D, RS232 interface Ham Radio Outlet
Amateur Electronic Supply
WinRotor parallel port FunkBox (Germany)
Meade LX200 Astronomical telescope Meade, Inc.