When we developed our obstacle course to practice for MASA competition we needed a device or method to clock our cars.  I developed a DOS application, which uses a Radio Shack infrared light beam detector, to highly measure the time lap from start to finish.  The program is only 77,825 bytes.  To download the program click HERE.
To test the program type mcorp at your "C" prompt.  If you don't have the Radio Shack infrared detector connected to the com1 port use <ctrl> END to start timer, wait at least 10 seconds then press <ctrl> END to stop timer.  Follow on screen instructions.  To exit program type <alt> END.
If you have any questions, suggestions, and/or comments, Email them to me.
                                     Fraternally
                                      Bro. Tom