Dan, it was the
Rockwell Collins FMS800.
The Embedded GPS / Inertial Navigation System did indeed include a Y-code capable GPS as well as a Laser INS. But that was only a small part of the sytem; unfortunately the system which you and I were familiar with was only a partial version of the full version used on the Pacer Craig KC 135.
The 'heart' of the system was the CDU. This allowed the navigation method to be selected from either INS1 (the LINS) or INS2 (the old Carousel IV). Either could also be blended with GPS, or, in extremis, GPS-only was possible. However, using a steering signal from GPS-only often causes aberrant heading demands as the system updated, so should not be coupled to the autopilot in NAV mode.
If the whole thing went tits-up, it was, of course, still possible to bypass the CDU and use the old C-IV to drive the autopilot - always assuming that the food-powered interface device had backed up the waypoints correctly. Some of them simply couldn't be bothered.......
And, just for old time's sake, I give you:
'Snake' banned anyone from ever rubbing it off the board - it was still there when I left!
Your Cat Question for the day - what's in the unlabelled blue box on the left of the photo?
Regarding the use of 'High St.' GPS in airliner cabins, when I first had my Garmin nuvi 660 (no FM transmitter and Bluetooth disabled), I studied the in-flight magazine on board the aircraft in which I was travelling. Nowhere did it say that GPS was not to be used - and I had also read on PPRuNe that many airlines will allow passengers to use such things in the cruise when the belt signs are off. So I started using it - only to be told it was "Verboten!" by the Chief Girl. S/He said that "was the rule", but when I asked him/her to show me, s/he declined.
Since you left for foreign parts, handheld GPS has become almost as common in the UK now as cellphones were a few years ago. So you can expect more and more people to want to use them in flight - and yes, they do work - the top speed recorded on mine is 580 mph!
One of these days I'm determined to see how it copes with this: