NavList:

Paul, Dan, Antoine,

I was pleasantly surprised to find your comments about my posting celebrating the 50th anniversary of the HP-35 calculator, as I didn’t expect any - I should have known better.

Paul, thanks for the kind words. I don’t think it’s terribly old-fashioned to use a handheld calculator for simple calculation tasks. Using Excel or MatLab to balance a bank account is like using a sledgehammer to crack a walnut; these progarms will do it, but they were meant for more heavy-duty computation.  And of course, once one has used reverse Polish notation (RPN), no other form of calculator entry will do!  I hadn’t encountered the “ Enter  >  = ”  expression , but I’ve seen the equally smug “ HP calculators have no = ”.

Dan, I appreciate your list of resources and emulators.  I share your high opinion of Thomas Okken’s HP-42S emulators, Free42 and the newer Plus42  (https://thomasokken.com/free42/). They transform an iOS or Android smart phone into one of the best handheld programmable calculators ever made. Free42 is free, as expected, and Plus42, which displays the whole stack and has additional functions, is under US$ 10.  You reminded me of William F. Buckley’s sailing books. "Airborne" is about a 1970s Atlantic crossing with celestial navigation, and, as you point out, sight reduction with the HP NavPac for the HP-65.  "Atlantic High" describes a second (1980s) Atlantic crossing also with astronavigation, and sight reduction with the HP-41 (the first alphanumeric programmable calculator; another H-P first !) running a NavPac equivalent written by a friend, and C. Plath’s Navicomp. Both books describe the mechanics of celestial navigation and are well written, though the name-dropping pomposity becomes rather tedious pretty quickly.  A later book about a Pacific passage using navigation by Loran and early GPS is obviously less interesting for celestial enthusiasts.

Antoine, your thoughts on 2-D and 3-D coordinate transformations are very interesting, and I’ll keep them in mind. I wasn’t aware of the HP-41 emulator by HrastProgrammer you include in your post, so I had to look it up. One ideal feature of the HP-42S and its emulators (as mentioned in the previous paragraph) is that they are able to run the large library of programs written for the HP-41 series to which you allude.  I presume that modesty prevented you to mention that the HrastProgrammer emulator home page has a link (https://www.hrastprogrammer.com/AntoineDC10.jpg) to a charming photo of a very experienced pilot and navigator hard at work on his HP-48 series graphing calculator; not an emulator, but the real thing. It’s very appealing to match a face to a thoughtful voice frequently heard in NavList.

Best wishes,
RafaelC