HP calculator and computer models have numbers and letters after the brand name, HP. The company used this technique so consumers can easily distinguish one model from another. Through the history of HP calculators, there are some models that have numbers while others that have both numbers and letters. These numbers and letters have corresponding meanings that may prove helpful to consumers and those who collect all kinds of HP calculator.
HP did not just assign random numbers and letters as model names, like the first handheld HP scientific calculator, the HP-35. It got the model number because it had 35 keys. However, the rest of the early handheld models, like the HP-80, HP-45, HP-65, HP-90, did not get their model numbers from how many keys they had but were different from each other nonetheless.
The company’s calculator line-up grew from HP scientific calculators to business calculators, and then there are those with different features like programmability and printing. Some calculators are improved versions of previous models, and to make a distinction, HP added letters after model numbers like the HP-25C. This model was taken from the HP-25 and added a “Continuous Memory” feature, thus the letter C at the end. Later on, all models with “Continuous Memory” had a C after the model numbers like the HP-29C and HP-19C. Another example is the HP-97 and HP-97S where the HP-97S had a serial interface.
The first series of HP calculators that had letters after model numbers are those in the Spice or 30 series. The first four HP scientific calculators in this series did not have continuous memory like the HP-31E and HP-32E. Those that did have continuous memory had the letter C after the E, like the HP-33E/C and HP-38E/C.
Another HP calculator series with numbers and letters are the HP-41C, HP-41CV, and HP-41CX. The HP-41C was an improved version of the HP-67. It had 3 shift keys adding more functions to the calculator. The HP-41CV had data registers five times more than the HP-41C, the “V” was for Roman number five. With the HP-41CX, the X means “Extended” because this model was like the HP-41CV with built-in extensions, extended functions, and extended memory.
The first HP calculator model to reuse a name was the HP-10C because there was already an HP-10. However, this model was similar to the HP-31E rather than an improved version of the HP-10. The HP-10C was a handheld basic scientific programmable with built-in printer, which was a simpler model of the HP-19C. People started adding A after the model names, like the HP-10 became the HP-10A to distinguish it from the HP-10C, and later on with the HP-10B (All three models are totally different from each other).
The HP-75C handheld computer was the next handheld model after the HP-10C. It was soon followed by the HP-71B and HP-75D. The HP-75D was like the HP-75C with a port for a barcode reader. The HP-94 model series followed the same pattern with the HP-94D, HP-94E, and HP-94F. The letters D, E, and F signify the three handheld models’ memory capacity having 64k, 128k, and 256k respectively. After this series, HP went back using just a “C” with the HP-18C and HP-28C.
The next series of calculators from HP used the B and S letters which stood for Business and Scientific, like the HP-19B and HP-28S. Then, the company stuck with the letters B and S for HP business calculators like the HP-10B, HP-14B, HP-20S, and HP-42S. After these, models like the HP-19BII, HP-17BII, and HP-32SII came out as improved versions (with RPN and algebraic notation) of earlier models without the II in the name. Models like the HP48SX stood for scientific expandable, the version without extensions were called HP48S. The next HP calculator models like the HP95LX and HP95LX1MB had a Lotus expandable feature and one model had 1 megabyte RAM. The models HP48G and HP48GX are new versions of the HP48S and HP48SX. The G stood for graphical calculator.
HP calculators started with numbers as model names, and then as their line of calculators grew they added letters after the numbers to mark improvements or added features. Understanding the trend on how HP calculators are named can help those who want to know about these calculators or if you want to start collecting, this information will guide you through different HP calculators and easily determine how different each model is from another.