HP-65
HP-65 keyboard and display | |
| Type | Programmable |
|---|---|
| Introduced | 1974 |
| Calculator | |
| Entry mode | RPN key stroke |
| Display type | Red LED seven-segment display |
| Display size | 15 digits (decimal point uses one digit), (±10±99) |
| CPU | |
| Processor | proprietary |
| Programming | |
| Programming language(s) | key codes |
| Memory register | 8 (9) plus 4-level working stack |
| Program steps | 100 |
| Other | |
| Power supply | Internal rechargeable battery or 115/230 V AC, 5 W |
| Weight | Calculator: 11 oz (310 g), recharger: 5 oz (140 g) |
| Dimensions | Length: 6.0 inches (150 mm), width: 3.2 inches (81 mm), height: 0.7–1.4 inches (18–36 mm) |
The HP-65 is the first magnetic card-programmable handheld calculator. Introduced by Hewlett-Packard in 1974 at an MSRP of $795 (equivalent to $5,069 in 2024), it featured nine storage registers and room for 100 keystroke instructions. It also included a magnetic card reader/writer to save and load programs. Like all Hewlett-Packard calculators of the era and most since, the HP-65 used Reverse Polish Notation (RPN) and a four-level automatic operand stack.
Bill Hewlett's design requirement was that the calculator should fit in his shirt pocket. That is one reason for the tapered depth of the calculator. The magnetic program cards are fed in at the thick end of the calculator under the LED display. The documentation for the programs in the calculator is very complete, including algorithms for hundreds of applications, including the solutions of differential equations, stock price estimation, statistics, and so forth.