I've now got the HP-97 up and running in Nonpareil well enough that I can start debugging the printer instructions. It's taken a lot of time studying disassembled 67 and 97 firmware to get to this point.
The most recent hurdle was figuring out that the paper advance button sets one of the ACT flags if the button is NOT pressed. Previously I wasn't getting anything on the display, and the code seemed to be stuck in a loop, the purpose of which was unknown.
Once the 97 is done, the 19C should follow very quickly, as it uses hardware nearly identical to the 97, other than having no card reader and fewer keys. The 91, 92, and 95C should also be easy, but I don't yet have ROM dumps.
I'm hoping to get a new release of Nonpareil finished up in time for HHC 2008. The main changes will be new model support (67, 97, 19C, 29C, and possibly the 10C) and some bug fixes. There's a lot more changes under the hood.
For ROM licensing reasons the 11C, 12C, 15C, and 16C will not be present in the main Nonpareil package, but will instead be part of a separate Voyager package. The details of the Voyager package have not yet been determined.