The HP25 was the first HP calculator I had. I got the 25 just before the HP25C came out and Hewlett Packard swapped it over for the newer model. They were great.

The HP25C had “continuous” (CMOS) memory. When you switched the calculator off it remembered the programs you had entered into it. The HP25 (and all the others of the time) forgot the lot when you switched them off.

You can get a java based HP25 emulator from
www.hpmuseum.org

It’s not a HP25 but you can also use our free hp21 calculator emulator.

Or, if your interest includes something more up-market, consider our hp67 calculator emulator.

It's only fair to share...