HP-41CX Alphanumeric Handheld Computer, 1983
When the HP-41C handheld calculator was introduced in 1979, it was the first calculator that could display alphabetic characters as well as numbers. But more importantly, it was fully programmable and expandable. For many people, the HP-41C was their introduction to computer programming. At $295, it was less expensive than a personal computer, and - through the HP Interface Loop (HP-IL0) - it could be hooked up to a printer, plotter and mass-storage device.
By the time the HP-41CX was introduced, it was called a computer rather than a calculator. It had more than twice as many built-in functions and three times as much memory capacity as the HP-41C.
The HP-41 calculator series introduced a new concept: the calculator as the core of a complete system, rather than a self-contained unit.