| Inventory number: | |
| Brand: | Hewlett Packard |
| Model: | HP 21 |
| Serie: | Woodstock |
| Production year: | 1975 |
| Display: | LED |
| Functionality: | Scientific |
| Algebraic notation: | yes |
| RPN notation: | yes |
| Form factor: |
| Status: | To be tested - My own collection |
| Accessories: |
Woodstock 220 V power supply unit |