This feature time line lists the first time that features appeared on HP's calculators. Only calculators that introduced new features are included in this list.

The first Hewlett-Packard calculator. Scientific, floating point, programmable, a card reader and various options. The first to show the entire stack and use a CRT display. . . (The list of firsts for the first calculator is, of course, nearly endless.)

The first to support subroutines. "Dual display" showed two program lines while editing.

Not a calculator but a significant option for the HP 9100A/B. In addition to adding a lot of memory, this option added indirect addressing, storage arithmetic and memory protection for the first time.

The first HP to use IC chips. The first with expandable RAM, plug in ROM blocks and keyboard overlays. The first time that indirect addressing was allowed*. The first to use LEDs and the first to have a built-in printer (optional). The first with alphanumeric printing (via optional ROM.) First with label addressing. (Absolute/line addressing also allowed.) This was also the first time storage arithmetic appeared.*

* Both indirect addressing and storage arithmetic were previously available via a memory extension option to the HP 9100A/B. This was the first time these features were built-in.

Hewlett-Packard's first algebraic calculator complete with its own BASIC-like programming language. Compiled algebraic statements to an RPN-like machine language and decompiled them back into algebraic lines for editing. First Alphanumeric display (in addition to printing.) First implied multiply (4A meant 4 times A.) First with multicharacter labels (quoted strings.) First with a flag that indicated that an empty line had been entered allowing users to terminate a data list with a "blank line".

The first HP handheld. The first handheld with transcendental functions. The first handheld with RPN and a four-level stack. etc. Used 4 level RPN optimized for a single line display.

Hewlett-Packard's first calculator to be programmed in BASIC (with extensions including multiple line functions, output formatting and tape control). Matrix, string, plotter and peripheral I/O extensions to BASIC were available via ROM blocks. The first with a QWERTY keyboard.

HP's first business calculator. The first time-value-of-money (TVM) solver. The first date calculations {days between dates, date + number of days etc.) Bond calculations, depreciation, a true shift key, statistics functions, and user control of display format. Also the first and only time that the Enter key was labeled "Save".

The first with last X, numbered storage registers (9), trigonometric functions in degrees radians or grads, conversion constants, and memory register arithmetic (STO + 5). Some versions featured an unofficial non-quartz timer.

The first of HP's "personal" calculators to have printers. The first HPs to make the display optional.

The first programmable and first card reader/writer. The first base conversions (octal/decimal only). The first appearance of the tall keys with slanted front faces.

The first to have a quartz timer (with 10 splits) and time calculations. Conversion functions instead of conversion factors.

The first to have the engineering display format.

The first battery powered printing calculator.

The first "do everything" calculator (business, statistical, scientific, but no programming.)

The first with "continuous memory" - a form of low power CMOS to which a small amount of power was supplied even when the calculator was off. A capacitor in the calculator allowed changing battery packs without losing memory. The HP 9100 had even more continuous core memory that needed no power at all.

These calculators were the first pair to be designed with the same programming language so magnetic cards could be interchanged between them. The HP-67 had "printing" commands but no printer.

First to support calculated addresses (both label and absolute). First to adjust all line address goto/gosubs when inserting and deleting lines. First appearance of FOR/NEXT loops. First high end RPN desktop with a single line display and 4 level RPN. First time "autostart" appeared which optionally caused the calculator to load and run the first program on tape when it was turned on.

HP's first and only adding machine and their first handheld printing calculator.

The first calculator with "Partition Programming".

Improved time value of money solver. Improved bond features, depreciation, internal rate of return. Also, the first with switches to choose 360- or 365-day years and payments at the beginning or end of each term.

HP's first and only calculator watch and first small algebraic model. The first with multiple data types (floating point numbers, dates and times) with ":" and "/" keys. The first with dynamic (time based) calculations.

The first programmable business calculator. The first programmable with dynamic conversion of register space into program space.

The first with numerical integration and Solve (a root finder.) For the first time x! calculated gamma(x+1) for negatives and non-integers.

First Alphanumeric, display, and keyboard. Allowed keys to be reassigned on a "user keyboard". HP's first with LCD display. Expansion ports allowed RAM/ROM and other options including the first handheld HP-IL interface.

The first with built-in complex and matrix math support.

HP's first and only computer scientist model with bases 2, 8, 10 and 16. Also had configurable wordsize and complement mode.

The first portable computer with the first hand pulled card reader.

The first OP/VS (operator precedence with value substitution) calculator. The first with IEEE math and the first to use the Saturn processor. The first handheld with QWERTY and numeric keypads.

HP's first DOS compatible laptop. The first to include Lotus 1-2-3 in firmware.

The first calculator programmed (by HP only) in RPL. The first folding calculator. The first with Infrared printing. The first with soft keys/menus and the first general solver.

The first to make RPL available to the user. The first plotting on a pocket calculator. The first object-oriented/many data types calculator. The first with symbolic math. The first solver for algebraic expressions or RPL programs.

The first calculator with directories.

The first with an RPN solver. First program checksumming.

The first to allow complex numbers in polar form was well as rectangular.

HP's ACO division closed down late in the year. Calculators remained in production but new development was non-existent for some time. The shutdown of calculator development had been predicted by many for years.