HP-67/97

The HP-67 and HP-97 were programmable, magnetic stripe card-reading calculators introduced by Hewlett-Packard in 1976. They were advanced for their time, offering powerful programming capabilities within a relatively compact form factor. The HP-67 was a pocket-sized calculator, while the HP-97 was a larger, desktop version that included a built-in thermal printer.

Both models used Reverse Polish Notation (RPN) for calculations, a characteristic of many HP calculators. Users entered numbers and then operators, rather than using the infix notation more common in basic calculators.

The primary difference between the two models, beyond size and the presence of the printer, was the number of program steps available. The HP-67 offered 224 merged program steps, while the HP-97 offered a significantly larger capacity, expandable via modules.

Their magnetic stripe card reader/writer allowed users to save and load programs and data. This feature was particularly useful for sharing programs and for preserving complex calculations. Pre-recorded programs for various applications were also available from HP and third parties.

The HP-67 and HP-97 were widely used by engineers, scientists, and other professionals who needed powerful, portable computing capabilities. They are considered iconic examples of early programmable calculators and remain sought after by collectors.