USMS aircraft had dual Littons, the kind that to enter a Jet Route, instead of just J38 from point A to point X, you had to enter every single fix on the route individually
There is a long story on just why we had the Littons, to be brief, 99% of the pilots, including me, did not want them, but the Department Head/Chief Pilot did, so that is what we ended up with. He was long gone by the time you showed up, but you probably know who I'm talking about.
However, even those were better than the INSs we first had, they could only hold nine (9) waypoints. On trips to South America the guy in the right seat and sometimes the FE had their heads down updating waypoints for almost the entire trip plugging in new waypoints.
It was a true pain in the butt.