asanal wrote on Aug 22^nd, 2010 at 7:25pm:

I cannot believe how 1960 Doppler Navigation like GPS can accept 2010 entire flight plan.

I don't believe the original equipment had that capability. My understanding is that you could set heading to fly and number of track miles on the next leg of the flight plan on one unit while the other was following the current leg. Switchover would occur either automatically or manually, depending on configurations, and you would then program the next leg, and so on.