From programmable calculator to pocket computer — and back again.

Programmable calculators become personal software machines

Before BASIC reached a shirt pocket, HP and Texas Instruments were already turning calculators into programmable personal tools. The HP-35 made scientific calculation pocket-sized; the HP-65 and HP-67 added stored programs and magnetic cards; TI answered with machines such as the SR-52 and TI-59; the later TI-95 PROCALC carried TI’s keystroke-programming tradition into a menu-driven alphanumeric machine. HP's alphanumeric HP-41C then made expansion modules, peripherals and a durable user-program ecosystem central to the product.

These machines still look like calculators because their interaction model is built around the keyboard and numerical workflow, not a general-purpose command line. But they establish the ideas that later calculator platforms inherit: persistent personal programs, specialist communities, expansion, downloadable or exchangeable software, and a user interface worth preserving across hardware generations.

HP Voyager compresses the mature RPN calculator into a thin, persistent platform

The HP-10C, 11C, 12C, 15C and 16C share the horizontal “Voyager” architecture and continuous-memory idea, but target very different users. The 10C is the simpler scientific model; the 11C expands scientific programmability; the 12C is financial; the 15C is the advanced scientific flagship with matrices, complex arithmetic, solve and integration; and the 16C is explicitly built for programmers with integer bases and bit-oriented operations.

Historically this matters because the Voyager family arrives at almost the same moment that Sharp and Epson are asking how far a calculator-sized or battery-powered computer can move toward general-purpose computing. HP doubles down on the opposite answer: keep the calculator form, make it extraordinarily good at a specialised workflow, preserve state, and let the keyboard itself become the expert interface.

BASIC turns the calculator-sized object into a pocket computer

Sharp's PC-1211, PC-1500, PC-1251 and later PC-1350 move in another direction. Instead of programming mainly through calculator keystrokes, the user gets BASIC, variables, loops, strings, a QWERTY keyboard, user RAM and increasingly capable LCD graphics. The PC-1500 can dock with printer/plotter and cassette hardware; the PC-1350 expands the display into a four-line graphics workspace.

The important change is conceptual: the pocket machine now behaves like a tiny personal computer whose owner writes programs rather than merely configuring calculations. Casio explored the same territory with the FX-702P and PB-700; Hewlett-Packard with the HP-75C and remarkably capable HP-71B; Texas Instruments with the CC-40 and later TI-74 BASICALC. The TI-74 is now playable here, alongside the museum’s Sharp and Casio pocket-computer exhibits. Pocket BASIC therefore belongs beside the home-computer revolution, not outside it: several calculator manufacturers were independently discovering the same general-purpose handheld format.

The same idea expands into the first complete portable computers

The Epson HX-20 is the point where this calculator/pocket-computer idea visibly grows into a complete self-contained portable computer. It was developed in parallel with the first Sharp pocket computers rather than as a simple linear successor, but the design trajectory is unmistakable: low-power processor, BASIC, LCD and battery operation are joined by a full keyboard, printer and storage options in one carrying machine. Epson's PX-8 and PX-4 later continue the portable branch with CP/M.

This is why the museum treats pocket computers as one root of mobile computing. The boundary between calculator, pocket computer, portable and eventually PDA was porous from the beginning.

Casio makes the display a mathematical workspace

Casio's fx-7000G of 1985 is widely recognised as the first graphing scientific calculator. The fx-8000G followed in that first generation. Once a 96×64 LCD can display functions, plots, menus and program output, the screen is no longer merely a result register: it becomes a general interactive surface.

The rest of the industry follows. HP's 28C/28S brings RPL and symbolic manipulation into a clamshell graphing calculator; TI's TI-81 in 1990 begins the school graphing line that will become one of the most durable educational platforms ever sold. Later TI-82/83/84, TI-85/86, Casio CFX and HP graphing families all inherit this new visual vocabulary.

The pocket computer refuses to stop at BASIC: C arrives

Casio's PB-1000 still belongs to the BASIC-and-assembly world, but its 192×32 display, QWERTY keyboard, touch-sensitive function areas and expansion already make it feel like a tiny development system. The PB-2000C then makes the remarkable jump to ANSI C. Optional ROM environments and the related FX-870P continue the idea that a serious compiled language belongs in a battery-powered pocket machine.

This corrects a common simplified history in which handheld programming jumps from BASIC pocket computers directly to 1990s PDAs. In the late 1980s, C was already being sold as the native programming proposition of a calculator-sized computer.

HP 48 turns the calculator into a persistent engineering workstation

The HP 48 series takes the specialist-platform path much further. Instead of imitating a small BASIC computer, it builds the environment around RPN, the RPL object system, a stack, soft menus, graphics, serial/infrared communication and persistent user objects. The 48SX adds expansion; the 48G/GX generation refines the platform, and the 48GX becomes the mature expandable flagship.

The Saturn CPU's nibble-oriented memory model is deeply matched to this world. More importantly, users invest years in the keyboard and RPL workflow. That creates a form of compatibility every bit as real as binary compatibility on a desktop PC.

TI-92 puts a 68000 computer-algebra system in your hands

Texas Instruments changes the high end with the TI-92 in 1995. Its wide body, QWERTY keyboard, 240×128 display, Motorola 68000 and computer algebra system make it look almost like a tiny terminal. The TI-89 repackages the same broad symbolic lineage into a conventional vertical calculator; Voyage 200 returns to the wide form; the 2004 TI-89 Titanium adds more flash and USB.

At the same time TI's separate TI-82/83/84 and TI-85/86 families dominate classrooms through familiarity, textbook support, link software and program exchange. TI therefore fights two wars at once: mass educational standardisation and high-end symbolic computing.

The Casio–TI–HP war is a platform war in miniature

Casio, Texas Instruments and Hewlett-Packard compete on far more than processor speed. Casio has early graphing leadership and broad educational ranges. TI turns the school graphing calculator into an ecosystem and adds a powerful CAS branch. HP defends an engineering culture built around RPN/RPL, strong programmability and unusually long continuity.

Teachers teach key sequences. Textbooks assume particular menus. Exams allow or prohibit particular capabilities. Users accumulate programs. Link software and cable standards create switching costs. The installed knowledge in a user's fingers becomes part of the platform. In that sense the calculator war repeats the PC industry on a smaller scale: architecture matters, but compatibility, distribution and community often matter more.

HP 50g shows that the interface can outlive the CPU

The HP 49g+ and 50g move the RPL lineage onto ARM-based hardware. The processor changes completely, storage and USB modernise, and performance rises dramatically, yet the user-facing environment still belongs to the HP 48/49 tradition. The platform is now clearly larger than its original CPU architecture.

The rivalry continues beyond the current playable collection

The museum's playable calculator timeline now spans TI's TI-74/TI-95, Z80 graphing family and 68000 TI-92 lineage through the HP 50g and TI-89 Titanium generation, but the category did not stop. TI-Nspire introduced a document-oriented platform; Casio continued through ClassPad, fx-9860G and colour fx-CG families; HP Prime moved to a colour touchscreen and modern CAS. These machines belong to the story even though they do not yet have emulator exhibits here.