Thanks to some help from HrastProgrammer, the HP-11C and HP-16C are now fully functional in the Nonpareil simulator. The display annunciators don’t work yet, but everything else seems fine.

Recently I’ve mostly been working on improvements to the simulation infrastructure. I’ve now got working code to save the state of any simulated calculator to a disk file as a gzip-compressed XML file, and to restore from such a file, so Nonpareil will finally have continuous memory.

There’s still some remaining work on making the save/restore work nicely with the File menu, and making it automatically save on exit and restore on startup. And after a restore, I need to force a display update.

Dealing with compressed XML using libxml2 is very easy. It’s a great library.

I decoded the “hex table” of the HP-16C. There are only 243 normal user programmable operations, so there are 13 illegal codes. I haven’t yet tried executing the illegal codes, but I did wedge them into a save state file to see how they would be decoded while stepping through memory in program mode. Of these, two are “WINDOW 8″ and “WINDOW 9″, four duplicate “FLOAT 6″ through “FLOAT 9″, five are “FLOAT B” through “FLOAT F”, and two duplicate “STO . 0″ and “0″.

I also spent some time matching up math routines in the HP-11C code with the VASM listings of the HP-41C math routines (file cn6b). They are almost identical, which isn’t too surprising.