Hewlett-Packard HP 91 (Topcat FELIX)
The Hewlett-Packard HP 91 is a scientific calculator with 12 digits precision and RPN (reverse polish notation) logic. It has 56 functions, 42 keys, and an LED (light-emitting diode) display typical of calculators of this era. The power source is 4x1.2V NiCd battery pack.
Facts at a glance:
| Feature | Value |
|---|---|
| Type | Scientific |
| Functions | 56 |
| Keys | 42 |
| Precision | 12 |
| Logic | RPN |
| Display type | LED |
| Printer | Yes |
| Length | 202mm |
| Width | 228mm |
| Thickness | 64mm |
| Weight | 1134g |
| Power Source | 4x1.2V NiCd battery pack |
| Year introduced | 1976 |
| Year discontinued | 1979 |
Replacements:
If you have a Hewlett-Packard HP 91 that is no longer working, you can consider replacing the calculator with a modern equivalent.
We suggest the following current model as a replacement: