To most calculator owners, the name Hewlett-Packard is synonymous with the highest quality in handheld calculating devices. HP can claim many of the firsts in this industry, including the first "shirt-pocket" scientific calculator (HP-35), the first pocket programmable calculator (the HP-65), the first pocket calculator with alphanumeric capability (the HP-41) and more. HP is also one of the few survivors of the "calculator wars" of the 1970s, remaining one of the preeminent calculator manufacturers in 1999. HP calculators are characterized by a very solid physical feel, robust design, great calculation accuracy, and reliable engineering solutions. HP magnetic card readers are a constant source of amazement for me: after their disintegrating transport wheels are repaired, they work like new even after 25 years. My first HP-65, for instance, has not yet had a single faulty read or write operation ever since I fixed its reader in the summer of 1999!
The Keystroke Product Line
The first pocket programmable calculator ever made, Hewlett-Packard's HP-65, already had a very sophisticated programming model. In addition to all the programming advantages offered by the RPN system, it also offered conditional and unconditional branching, labels, subroutines, and a partially merged instruction set. Perhaps it's no wonder that the programming model changed little over the years; its mature version, first introduced with the HP-67, remained largely the same over the years and was still used in HP's last series of RPN keystroke programmables, the Voyager series.
Classics/Topcats
HP's first product line of pocket/portable calculators. Strictly speaking, the HP-67/97/97S actually belong to the second generation: electronically, these machines use the technology of the "Woodstock" series. The appearance of the HP-67 places it in the Classic series, however.
| - | Model | Type | Display | Programming model | Programming features | Memory | Special functions |
 | HP-55 | RPN Scientific | 10+2 LED digits | Keystroke entry (49 program steps) | Conditionals, Branching | 20 numbers | Trigonometrics, Exponentials, Real-time clock |
 | HP-65 | RPN Scientific | 10+2 LED digits | Partially merged keystroke (100 program steps) | Conditionals, Branching, Subroutines, Labels | 9 numbers | Trigonometrics, Exponentials, Magnetic cards |
 | HP-67 | RPN Scientific | 10+2 LED digits | Fully-merged keystroke entry (224 program steps) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 26 numbers | Trigonometrics, Exponentials, Magnetic cards |
| No Image Available | HP-95C | RPN Scientific | 10+2 LED digits | Fully-merged keystroke entry (200 program steps) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 17 numbers | Trigonometrics, Exponentials, Linear regression, Continuous memory, Printer |
 | HP-97 | RPN Scientific | 10+2 LED digits | Fully-merged keystroke entry (224 program steps) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 26 numbers | Trigonometrics, Exponentials, Printer, Magnetic cards |
 | HP-97S | RPN Scientific | 10+2 LED digits | Fully-merged keystroke entry (224 program steps) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 26 numbers | Trigonometrics, Exponentials, Printer, Magnetic cards |
Woodstocks
HP's second pocket product line featured several machines in a very small, pleasant form factor. Unfortunately, the construction of the calculators provided for the uneven heating of the batteries during charging, leading to premature battery wear. The design of the charging circuit also made it possible for the calculator to receive excessive voltage when a battery pack was not properly inserted, causing the calculator's sensitive MOS circuits to fail.
| - | Model | Type | Display | Programming model | Programming features | Memory | Special functions |
 | HP-19C | RPN Scientific | 10(8+2) LED digits | Fully-merged keystroke entry (98 program steps) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 30 numbers | Trigonometrics, Exponentials, Continuous memory, Printer |
 | HP-25 | RPN Scientific | 10(8+2) LED digits | Fully-merged keystroke entry (49 program steps) | Conditionals, Branching | 8 numbers | Trigonometrics, Exponentials |
 | HP-25C | RPN Scientific | 10(8+2) LED digits | Fully-merged keystroke entry (49 program steps) | Conditionals, Branching | 8 numbers | Trigonometrics, Exponentials, Continuous memory |
 | HP-29C | RPN Scientific | 10(8+2) LED digits | Fully-merged keystroke entry (98 program steps) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 30 numbers | Trigonometrics, Exponentials, Continuous memory |
Spice
The third, and last, LED series of calculators from HP were plagued by a different problem. Initially, the calculators' components were held together by pressure; electronic components were not soldered onto the machines' flexible circuit boards. This led to numerous reliability complaints, so eventually HP returned to a more traditional design. The Spice series also featured the first business-oriented programmable machines, as well as HP's most sophisticated scientific calculator to date, the HP-34C.
| - | Model | Type | Display | Programming model | Programming features | Memory | Special functions |
 | HP-33C | RPN Scientific | 10(8+2) LED digits | Fully-merged keystroke entry (49 program steps) | Conditionals, Branching | 8 numbers | Trigonometrics, Exponentials, Continuous memory |
 | HP-33E | RPN Scientific | 10(8+2) LED digits | Fully-merged keystroke entry (49 program steps) | Conditionals, Branching | 8 numbers | Trigonometrics, Exponentials |
 | HP-34C | RPN Scientific | 10(8+2) LED digits | Fully-merged keystroke entry (210 program steps) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 21(1) numbers | Trigonometrics, Exponentials, Linear regression, Solver, Integration, Continuous memory |
 | HP-38C | Financial | 10(8+2) LED digits | Fully-merged keystroke entry (99 program steps) | Conditionals, Branching | 20(7) numbers | Exponentials, Linear regression, Financial, Continuous memory |
 | HP-38E | Financial | 10(8+2) LED digits | Fully-merged keystroke entry (99 program steps) | Conditionals, Branching | 20(7) numbers | Exponentials, Linear regression, Financial |
Voyagers
The first LCD product line from Hewlett-Packard contains some of the most successful, most popular calculators ever built. Of these machines, the HP-12C is still in production; the HP-15C remains one of the most sought after scientific calculator to date, and the HP-16C remains a favorite calculator for programmers. These machines were legendary for their amazingly low power consumption: many owners report that their machines still run on the original set of high-quality silver-oxide batteries after nearly 20 years!
| - | Model | Type | Display | Programming model | Programming features | Memory | Special functions |
 | HP-10C | RPN Scientific | 10(7+2) LCD digits | Fully-merged keystroke entry (79 program steps) | Conditionals, Branching | 10(0) numbers | Trigonometrics, Exponentials, Linear regression, Continuous memory |
 | HP-11C | RPN Scientific | 10(7+2) LCD digits | Fully-merged keystroke entry (203 program steps) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 20(0) numbers | Trigonometrics, Exponentials, Linear regression, Continuous memory |
 | HP-12C | Financial | 10(7+2) LCD digits | Fully-merged keystroke entry (99 program steps) | Conditionals, Branching | 20(7) numbers | Exponentials, Linear regression, Financial, Continuous memory |
 | HP-12C Platinum | Financial | 10(7+2) LCD digits | Fully-merged keystroke entry (400 program steps) | Conditionals, Branching | 20 numbers | Exponentials, Linear regression, Financial, Continuous memory |
 | HP-15C | RPN Scientific | 10(7+2) LCD digits | Fully-merged keystroke entry (455 program steps) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 65(0) numbers | Trigonometrics, Exponentials, Linear regression, Integration, Complex, Continuous memory, Matrix |
 | HP-16C | N/A | 10(7+2) LCD digits | Fully-merged keystroke entry (203 program steps) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 203(0) bytes | Continuous memory, baseN |
Coconuts
A stunning calculator even by today's standards, more than 20 years after its introduction, the HP-41C remains one of the best handheld calculating devices ever conceived. The HP-41C line remained in production for over 10 years, practically defining the high-end calculator industry throughout the 1980s. Numerous machines remain in use today, no doubt due in part to versatility offered by the calculator's four expansion ports. The HP-41C has been used in the most exotic places, including the Space Shuttle or the cockpit of the Concorde. The calculator's major (and perhaps only) fault is a less than robust construction, with screwposts that easily crack, internal pressure contacts that can fail unexpectedly, and a flexible circuit assembly subject to corrosion.
| - | Model | Type | Display | Programming model | Programming features | Memory | Special functions |
 | HP-41C | RPN Scientific | 12 LCD 14-segment characters | Fully-merged keystroke entry (441 bytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 63(0) numbers | Trigonometrics, Exponentials, Linear regression, Continuous memory, Sound |
 | HP-41CV | RPN Scientific | 12 LCD 14-segment characters | Fully-merged keystroke entry (2233 bytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 319(0) numbers | Trigonometrics, Exponentials, Linear regression, Continuous memory, Sound |
 | HP-41CX | RPN Scientific | 12 LCD 14-segment characters | Fully-merged keystroke entry (2233 bytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 319(0) numbers | Trigonometrics, Exponentials, Linear regression, Continuous memory, Real-time clock, Sound |
 | HP-41 Option 001 | RPN Scientific | 12 LCD 14-segment characters | Fully-merged keystroke entry (2233 bytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 319(0) numbers | Trigonometrics, Exponentials, Linear regression, Continuous memory, Sound |
Pioneers
HP's last pocket calculator line to date that contains keystroke-programmable models also featured another legendary calculator: the HP-42S. Built on the success of the HP-41C line, offering a similar programming model, a healthy 8 kB of memory, and even simple graphical capabilities, the HP-42S remains the most sought after engineering calculator today, even more than 5 years after HP ended its production for reasons known only to pointy-haired bosses...
This product line also contains the only two non-RPN keystroke programmables from HP: the HP-20S and the HP-21S. And to prove that perhaps those bosses are not so pointy-haired after all, they recently revived this line of calculators with the HP-33S, a reincarnation of the HP-32S with a great deal more memory and, for the RPN-haters among you, an algebraic mode.
| - | Model | Type | Display | Programming model | Programming features | Memory | Special functions |
 | HP-20S | Scientific | 12(9+2) LCD digits | Fully-merged keystroke entry (100 program steps) | Conditionals, Branching, Subroutines, Labels | 10 numbers | Trigonometrics, Exponentials, Continuous memory, Equation library |
 | HP-21S | Scientific | 12(9+2) LCD digits | Fully-merged keystroke entry (100 program steps) | Conditionals, Branching, Subroutines, Labels | 10 numbers | Trigonometrics, Exponentials, Linear regression, Continuous memory, Equation library |
 | HP-32S | RPN Scientific | 12 LCD characters | Fully-merged keystroke entry (390 bytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 27(0) numbers | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Solver, Integration, Complex, Continuous memory, baseN |
 | HP-32SII | RPN Scientific | 12 LCD characters | Fully-merged keystroke entry (390 bytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 27(0) numbers | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Solver, Integration, Fractions, Complex, Continuous memory, baseN |
 | HP-32SII Silver | RPN Scientific | 12 LCD characters | Fully-merged keystroke entry (390 bytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 27(0) numbers | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Solver, Integration, Fractions, Complex, Continuous memory, baseN |
 | HP-33S | RPN Scientific | 2×14 LCD characters | Fully-merged keystroke entry (32 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 32(0) kilobytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Solver, Integration, Fractions, Complex, Continuous memory, baseN, Unit conversions |
 | HP-35S | RPN Scientific | 2×14 LCD characters | Fully-merged keystroke entry (31 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 31(0) kilobytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Solver, Integration, Fractions, Complex, Continuous memory, baseN, Unit conversions, Constants |
 | HP-42S | Graphing | 131×16 LCD pixels | Fully-merged keystroke entry (7 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 7(0) kilobytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Graphing, Solver, Integration, Complex, Financial, Continuous memory, Sound, Matrix, baseN, Unit conversions |
The HP Solver
Hewlett-Packard first introduced a built-in equation solver with the HP-34C. This solver function, however, operated on a traditional keystroke program. It wasn't until the Champion and Pioneer product lines that HP began producing a series of (mainly business) calculators in which a built-in solver represented the primary (or only) means of programming: user-defined formulae were entered using algebraic syntax, and the built-in solver isolated variables and solved for them numerically.
Pioneers
In addition to featuring several popular keystroke-programmable calculators, the Pioneer product line also included business models and algebraic scientific calculators with HP Solver functionality.
| - | Model | Type | Display | Programming model | Programming features | Memory | Special functions |
 | HP-17B | Financial | 131×16 LCD pixels | Formula programming (6700 kilobytes) | Conditionals, Branching | 6700(0) bytes | Exponentials, Linear regression, Solver, Financial, Continuous memory, Sound, Matrix |
 | HP-17BII | Financial | 131×16 LCD pixels | Formula programming (6700 kilobytes) | Conditionals, Branching | 6700(0) bytes | Exponentials, Linear regression, Solver, Financial, Continuous memory, Sound, Matrix |
| Unconfirmed sighting | HP-17BII+ | Financial | 2×22 LCD characters | Formula programming (32 kilobytes) | Conditionals, Branching | 32(0) kilobytes | Exponentials, Hyperbolics, Linear regression, Solver, Financial, Continuous memory, Sound, Matrix |
 | HP-22S | Scientific | 12(9+2) LCD digits | Formula programming (371 bytes) | 371(0) bytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Solver, Continuous memory, baseN, Unit conversions, Equation library | |
 | HP-27S | Scientific | 131×16 LCD pixels | Formula programming (6912 bytes) | Conditionals, Branching | 6912(0) bytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Solver, Financial, Continuous memory, Real-time clock, Sound, baseN |
Champions
The Champion calculator line featured "folding" calculators. Although these calculators remained popular, the folding design wasn't universally loved, due to its fragility and the difficulty of using the calculators when held in one hand (or even both hands).
| - | Model | Type | Display | Programming model | Programming features | Memory | Special functions |
 | HP-18C | Scientific | 137×32 LCD pixels | Formula programming (6700 kilobytes) | Conditionals, Branching | 6700(0) bytes | Trigonometrics, Exponentials, Linear regression, Solver, Financial, Continuous memory, Sound, Matrix |
 | HP-19B | Scientific | 137×32 LCD pixels | Formula programming (6700 bytes) | Conditionals, Branching | 6700(0) bytes | Trigonometrics, Exponentials, Linear regression, Solver, Financial, Continuous memory, Sound, Matrix |
 | HP-19BII | Scientific | 137×32 LCD pixels | Formula programming (6700 bytes) | Conditionals, Branching | 6700(0) bytes | Trigonometrics, Exponentials, Linear regression, Solver, Financial, Continuous memory, Sound, Matrix |
| Unconfirmed sighting | HP-19BII+ | N/A | LCD |
Programming with Aplets
While Hewlett-Packard continued to produce the highest quality calculators, it also continued to lose market share to other manufacturers, Casio and Texas Instruments the most notable among them, who focused on the lucrative educational market. An attempt to regain a foothold in this area was represented by the HP-38G, a graphing calculator with a new, education-oriented programming model: HP Aplets. The two newer models, the HP-39G and the HP-40G, represent a continuation of this concept. Along with these models, HP also introduced a low-cost scientific calculator, the HP-30S.
A Brave New World
Although it is officially not considered a programmable, the HP-30S nevertheless has a formula memory.
| - | Model | Type | Display | Programming model | Programming features | Memory | Special functions |
 | HP-30S | Scientific | 10+2 LCD digits | Formula programming (80 bytes) | 11 numbers | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Solver, Fractions, Continuous memory, baseN |
Charlemagne
HP's last series of calculator products went through a series of revisions throughout a product lifetime that extends over a decade. An offshoot of this product line was a series of graphing educational calculators.
| - | Model | Type | Display | Programming model | Programming features | Memory | Special functions |
 | HP-38G | Graphing | 131×64 LCD pixels | HP Aplets (32 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 32(0) kilobytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Graphing, Solver, Integration, Continuous memory, Sound, Matrix |
 | HP-39G | Graphing | 131×64 LCD pixels | HP Aplets (256 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 256(0) kilobytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Graphing, Solver, Integration, Continuous memory, Sound, Matrix |
| No Image Available | HP-39G+ | Graphing | LCD pixels | Graphing | |||
| No Image Available | HP-39GII | Graphing | LCD pixels | Graphing | |||
 | HP-39GS | Graphing | 131×64 LCD pixels | HP Aplets (256 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 256(0) kilobytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Graphing, Solver, Integration, Continuous memory, Sound, Matrix |
| No Image Available | HP-40G | Graphing | 131×64 LCD pixels | HP Aplets (256 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 256(0) kilobytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Graphing, Solver, Integration, Symbolics, Continuous memory, Sound, Matrix |
| No Image Available | HP-40GS | Graphing | LCD pixels | Graphing |
Reverse Polish Language Graphing Calculators
In 1988, Hewlett-Packard introduced a stunning new machine. The HP-28C was not just a graphing calculator, it was also a calculator featuring a whole new programming model: the Reverse Polish Language. RPL successfully combines the ease and intuitiveness, not to mention the efficiency of keystroke macro programming with a sophisticted object model that puts "high-end" object oriented programming languages like C++ to shame.
Champions
The Champion series, recognizable for the folding "clamshell" design, featured HP's first modern RPL graphing calculators.
| - | Model | Type | Display | Programming model | Programming features | Memory | Special functions |
 | HP-28C | Graphing | 137×32 LCD pixels | Reverse Polish Language (2 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 2(0) kilobytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Graphing, Solver, Integration, Fractions, Complex, Symbolics, Continuous memory, Real-time clock, Sound, Matrix, baseN, Unit conversions, Constants |
 | HP-28S | Graphing | 137×32 LCD pixels | Reverse Polish Language (32 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 32(0) kilobytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Graphing, Solver, Integration, Fractions, Complex, Symbolics, Continuous memory, Real-time clock, Sound, Matrix, baseN, Unit conversions, Constants |
Charlemagne
The Charlemagne product line continues to feature the most top-of-the line of all HP calculator models produced to date, the HP-49G, with an astounding 1.5 MB of memory capacity, and a sophisticated symbolic algebra capability.
| - | Model | Type | Display | Programming model | Programming features | Memory | Special functions |
 | HP-48G | Graphing | 131×64 LCD pixels | Reverse Polish Language (32 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 32(0) kilobytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Graphing, Solver, Integration, Fractions, Complex, Symbolics, Financial, Continuous memory, Real-time clock, Sound, Matrix, baseN, Unit conversions, Constants, Equation library |
 | HP-48G+ | Graphing | 131×64 LCD pixels | Reverse Polish Language (128 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 128(0) kilobytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Graphing, Solver, Integration, Fractions, Complex, Symbolics, Financial, Continuous memory, Real-time clock, Sound, Matrix, baseN, Unit conversions, Constants, Equation library |
 | HP-48GX | Graphing | 131×64 LCD pixels | Reverse Polish Language (128 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 128(0) kilobytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Graphing, Solver, Integration, Fractions, Complex, Symbolics, Financial, Continuous memory, Real-time clock, Sound, Matrix, baseN, Unit conversions, Constants, Equation library |
 | HP-48GII | Graphing | 131×64 LCD pixels | Reverse Polish Language (128 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 128(0) kilobytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Graphing, Solver, Integration, Fractions, Complex, Symbolics, Financial, Continuous memory, Real-time clock, Sound, Matrix, baseN, Unit conversions, Constants, Equation library |
 | HP-48S | Graphing | 131×64 LCD pixels | Reverse Polish Language (32 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 32(0) kilobytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Graphing, Solver, Integration, Fractions, Complex, Symbolics, Financial, Continuous memory, Real-time clock, Sound, Matrix, baseN, Unit conversions |
 | HP-48SX | Graphing | 131×64 LCD pixels | Reverse Polish Language (32 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 32(0) kilobytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Graphing, Solver, Integration, Fractions, Complex, Symbolics, Financial, Continuous memory, Real-time clock, Sound, Matrix, baseN, Unit conversions |
 | HP-49G | Graphing | 131×64 LCD pixels | Reverse Polish Language (512 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 512(0) kilobytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Graphing, Solver, Integration, Fractions, Complex, Symbolics, Financial, Continuous memory, Real-time clock, Sound, Matrix, baseN, Unit conversions, Constants, Equation library |
| No Image Available | HP-49G+ | Graphing | 131×80 LCD pixels | Reverse Polish Language (512 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 512(0) kilobytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Graphing, Solver, Integration, Fractions, Complex, Symbolics, Financial, Continuous memory, Real-time clock, Sound, Matrix, baseN, Unit conversions, Constants, Equation library |
 | HP-50G | Graphing | 131×80 LCD pixels | Reverse Polish Language (1536 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 512(0) kilobytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Graphing, Solver, Integration, Fractions, Complex, Symbolics, Financial, Continuous memory, Real-time clock, Sound, Matrix, baseN, Unit conversions, Constants, Equation library |
| No Image Available | Prime | Graphing | CLCD pixels | Graphing, Continuous memory |
Pocket Computers
The introduction of low-power C-MOS circuits, low-power liquid crystal displays, and high component density made it possible in the early 1980s to pack the power of an entire personal computer in a pocket-sized package. Hewlett-Packard joined the bandwagon with its BASIC-programmable computer/calculator products, that also inherited the flexible expandability of the HP-41 product line. Later, HP was among the first to produce MS-DOS compatible pocket computers, and remains a preeminent manufacturer of handheld Windows CE devices today.
BASIC computers
HP's BASIC-programmable handheld product line featured the HP-71B, the world's first pocket device featuring an ANSI-compatible floating point library.
| - | Model | Type | Display | Programming model | Programming features | Memory | Special functions |
 | HP-71B | Scientific | 22 LCD characters | BASIC (16 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 16(0) kilobytes | Trigonometrics, Exponentials, Continuous memory, Real-time clock, Sound, Magnetic cards |
 | HP-75C | BASIC Programmable | 32 LCD characters | BASIC (16 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 16(0) kilobytes | Trigonometrics, Exponentials, Continuous memory, Real-time clock, Sound, Magnetic cards |
 | HP-75D | BASIC Programmable | 32 LCD characters | BASIC (32 kilobytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 32(0) kilobytes | Trigonometrics, Exponentials, Continuous memory, Real-time clock, Sound, Magnetic cards |
MS-DOS computers
The HP-95LX was one of the world's first pocket computers offering true MS-DOS compatibility; the HP-200LX, although discontinued years ago, remains a popular PDA even today.
| - | Model | Type | Display | Programming model | Programming features | Memory | Special functions |
 | HP-95LX | Graphing | 240×128 LCD pixels | Spreadsheet data (1 megabytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 1(0) megabytes | Trigonometrics, Exponentials, Linear regression, Graphing, Solver, Financial, Continuous memory, Real-time clock, Sound, Matrix, baseN |
 | HP-100LX | Graphing | 640×200 LCD pixels | Spreadsheet data (1 megabytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 1(0) megabytes | Trigonometrics, Exponentials, Linear regression, Graphing, Solver, Financial, Continuous memory, Real-time clock, Sound, Matrix, baseN |
 | HP-200LX | Graphing | 640×200 LCD pixels | Spreadsheet data (1 megabytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 1(0) megabytes | Trigonometrics, Exponentials, Linear regression, Graphing, Solver, Financial, Continuous memory, Real-time clock, Sound, Matrix, baseN |
 | HP-700LX | Graphing | 640×200 LCD pixels | Spreadsheet data (1 megabytes) | Conditionals, Branching, Subroutines, Labels, Indirect addressing | 1(0) megabytes | Trigonometrics, Exponentials, Linear regression, Graphing, Solver, Financial, Continuous memory, Real-time clock, Sound, Matrix, baseN |
One Of A Kind
The Xpander was a dream that never happened: an educational product based on the Windows CE 3.0 operating system.
| - | Model | Type | Display | Programming model | Programming features | Memory | Special functions |
 | HP Xpander | Graphing | 240×320 LCD pixels | Formula programming (8 megabytes) | Subroutines | 8(0) megabytes | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Graphing, Solver, Integration, Continuous memory, Matrix |
Other Models
Hewlett-Packard models that were not yet added to any of the categories listed so far are shown below.
| - | Model | Type | Display | Programming model | Programming features | Memory | Special functions |
| No Image Available | HP-9G | Graphing | 35×23 LCD pixels | Formula programming (400 program steps) | Conditionals, Branching, Subroutines, Labels | 26 numbers | Trigonometrics, Exponentials, Hyperbolics, Linear regression, Graphing, Fractions, Complex, Continuous memory, baseN, Unit conversions, Constants |
| No Image Available | HP-30B | RPN Scientific | LCD digits | ( program steps) | Conditionals, Branching, Subroutines | Trigonometrics, Exponentials, Solver, Financial, Continuous memory |
Variants/OEM Versions
Some Hewlett-Packard calculators were sold in Japan under the brandname Yokogawa-Hewlett-Packard (YHP). Model numbers remained the same.
