The HP-55 |
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| Type | Programmable |
|---|---|
| Introduced | 1975 |
| Calculator | |
| Entry mode | RPN |
| Display Type | Seven-segment display |
| Display Size | 10 + 2 |
| Programming | |
| Other | |
The HP-55 was a programmable handheld calculator; a lower-cost alternative to the HP-65. Introduced by Hewlett-Packard in 1975, it featured twenty storage registers and room for 49 keystroke instructions. Its outward appearance was identical to the HP-65, except that a few key functions were different and that it did not have a magnetic card reader/writer. Like all Hewlett-Packard calculators of the era and most since, the HP-55 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 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.
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