If you are using LabVIEW or LabWindows/CVI you can find a driver for this instrument at this website
. Select Tektronix/CDS as the manufacturer and enter 73A-453 in the Additional Keywords and hit go. This will bring up the two drivers. When you install this on your computer put it in the following directory:
C:\Program Files\National Instruments\LabVIEW 7.1\instr.lib
If you place it here the functions will show up in LabVIEW if you go to the Block Diagram's Functions Palette>>Instrument I/O>>Instrument Drivers. This should get you started. If you have more questions please repost.