I find that one of the best ways to learn about a calculator is to use it. Given that they aren’t made anymore, many people use emulators instead. There are a number of emulators available and most are quite good.
I make two of the emulators. One is a functional equivalent and the other is a microcode emulator. The second one is my favorite because it is a closer match to the real thing; but both are available on this site (see below).
You can run either of my HP-67 emulators for free in any web browser on any computer and, if you “install it”, you can even run it when you’re not connected to the internet.
You can also buy a copy of either emulator for a nominal sum if you’re interested in seeing what’s inside it and how it works, or if you just like to make sure you always have it. See the links for details.
Using the HP-67 Calculator
There are programs available at HP-67 programs and products/hp67-cards. Any programs that are copyright Hewlett-Packard from 40 years ago are only provided for the convenience of people who purchased a copy of them at the time. If you no longer have the manuals explaining how to use the programs, I believe they are included in the hpmuseum.org CD.
Articles I’ve written on the calculator can be found at HP-67 articles.
There is a help page for the calculator (and emulators) at HP-67 Help
Under the cover
Each program step is stored in a single byte in the calculator memory. There is a list of these values in Eric’s HP67 Hex Codes.
Here is a list of HP-67 calculator items that I have available. You can click a picture for a bigger view of the picture, or the name of an item for more information about it.