Seeking a timeline of feature introductions by HP

[EdS2]

Good points...
First ARM based (2003, HP 49g+ runs a Saturn emulation)
First native ARM based (? 2008, HP 20b maybe?)

Still wondering about
First anniversary tribute machine (2007, HP 35s)
which is to say, it was intended to celebrate the anniversary of the HP-35 but was in so many ways not a re-offering of the same function.

The HP 35s does offer high precision and great range but I doubt it was a first for HP. The FDISP options for fractions, and the unit conversion offerings, seem notable but again I don't suppose this was a first. Is it the first to combine fractions and conversions, so ​3 15⁄16 inches is a valid input?

Was the HP 35s the first to have two index memories (I and J)? I feel like I'm clutching at straws...