Everyday use of programmable Calculators without Continuous Memory/Storage Devices

[Andres]

I had an HP-25 non-C and used it during the first years of my electronics engineering course, from mid 1976 to mid 1980, when I upgraded to an HP-41C. At the time when I programmed the 25, it was easy to enter programs by hand and from memory to solve exercises; for instance 2 x 2 simultaneous equations, root finders, random number generation and statistics, factorials, numerical integration per Simpson's rule, etc. I also had a binder whose pages were photocopies of the blank programming form included with the Application Programs handbook, and those forms were handwritten, they were handy to track register contents during program development. At the time, programs were short, simple and very procedural, so after learning the procedure, remembering the program was easy. It was kind of singing the lyrics of a popular song.