See this FIS timing Guide. Timing without wire is covered with nice diagrams.
2 Pairs of wires = two timers at the finish
1 Pair of wires = two timers at the finish, one timer at the start.
0 Pairs wire = two timers at the finish, two timers at the start.
The TED doesn't eliminate the need for a timer at the start, it only provides a way to get the data, or impulse from start to finish and is basically seen the same way as a computer, its a nice accessory, but completely un-needed to time within the rules.
You must still have manual timekeeping in place for all events.
Jenna