# saturnus

> saturnus runs classic HP calculators in the browser: the HP 48SX, 48GX, 49G, 38G, 39G, 40G, 42S, 27S, 17BII, 17B, 28S and 19BII. These docs cover the models, their commands, how the Saturn processor works and how to move files to a real calculator.

Every docs page is also Markdown: its address with `.md` (`/saturnus/docs/48gx/` is `/saturnus/docs/48gx.md`). The command reference has one Markdown file per model with every command, its stack effect, a description and examples with their results from the emulated calculator.

## Docs

- [saturnus docs](https://ractive.ch/saturnus/docs/index.md): The HP calculators saturnus runs, their commands, how the Saturn processor works and how to move files to a real calculator.

## Models

- [HP 17B](https://ractive.ch/saturnus/docs/17b.md): HP's algebraic business calculator of 1988 to 1990 with a solver for your own equations, its history, what makes it special and how saturnus runs it.
- [HP 17BII](https://ractive.ch/saturnus/docs/17bii.md): HP's business calculator of 1990 with RPN or algebraic entry, its history, what makes it special and how saturnus runs it.
- [HP 19BII](https://ractive.ch/saturnus/docs/19bii.md): HP's clamshell business calculator of 1990 with a letter keyboard and RPN or algebraic entry, its history, what makes it special and how saturnus runs it.
- [HP 27S](https://ractive.ch/saturnus/docs/27s.md): HP's first algebraic scientific calculator, of 1988, with a solver for your own equations, its history, what makes it special and how saturnus runs it.
- [HP 28S](https://ractive.ch/saturnus/docs/28s.md): HP's clamshell RPL calculator of 1988 to 1992 with symbolic algebra, its history, what makes it special and how saturnus runs it.
- [HP 38G](https://ractive.ch/saturnus/docs/38g.md): HP's 1995 graphing calculator for school maths and science, built around aplets; its history, what makes it special and how saturnus runs it.
- [HP 39G](https://ractive.ch/saturnus/docs/39g.md): HP's aplet-based school graphing calculator of 2000, the HP 38G's successor; its history, what makes it special and how saturnus runs it.
- [HP 40G](https://ractive.ch/saturnus/docs/40g.md): HP's aplet-based school graphing calculator of 2000 with the HP 49G's computer algebra and no infrared; its history, what makes it special and how saturnus runs it.
- [HP 42S](https://ractive.ch/saturnus/docs/42s.md): HP's RPN scientific of 1988 that runs HP-41 programs, its history, what makes it special and how saturnus runs it.
- [HP 48GX](https://ractive.ch/saturnus/docs/48gx.md): HP's RPL graphing calculator of 1993 to 2003, its history, what makes it special and how saturnus runs it.
- [HP 48SX](https://ractive.ch/saturnus/docs/48sx.md): HP's first RPL calculator with card slots, a serial port and two-way infrared, sold from 1990; its history, what makes it special and how saturnus runs it.
- [HP 49G](https://ractive.ch/saturnus/docs/49g.md): HP's 1999 graphing calculator with computer algebra and a ROM in flash memory; its history, what makes it special and how saturnus runs it.

## Command reference

- [Command reference](https://ractive.ch/saturnus/docs/commands.md): Every command of the 12 calculators saturnus runs, with its stack effect, what it does and examples with their results from the emulated calculator.
- [HP 48SX commands](https://ractive.ch/saturnus/docs/commands/48sx.md): 397 commands with their stack effects, descriptions and examples
- [HP 48GX commands](https://ractive.ch/saturnus/docs/commands/48gx.md): 517 commands with their stack effects, descriptions and examples
- [HP 49G commands](https://ractive.ch/saturnus/docs/commands/49g.md): 830 commands with their stack effects, descriptions and examples
- [HP 38G commands](https://ractive.ch/saturnus/docs/commands/38g.md): 208 functions with their keys, descriptions and examples
- [HP 39G commands](https://ractive.ch/saturnus/docs/commands/39g.md): 209 functions with their keys, descriptions and examples
- [HP 40G commands](https://ractive.ch/saturnus/docs/commands/40g.md): 209 functions with their keys, descriptions and examples
- [HP 42S commands](https://ractive.ch/saturnus/docs/commands/42s.md): 277 functions with their keys, descriptions and examples
- [HP 27S commands](https://ractive.ch/saturnus/docs/commands/27s.md): 251 functions with their keys, descriptions and examples
- [HP 17BII commands](https://ractive.ch/saturnus/docs/commands/17bii.md): 260 functions with their keys, descriptions and examples
- [HP 17B commands](https://ractive.ch/saturnus/docs/commands/17b.md): 254 functions with their keys, descriptions and examples
- [HP 28S commands](https://ractive.ch/saturnus/docs/commands/28s.md): 260 commands with their stack effects, descriptions and examples
- [HP 19BII commands](https://ractive.ch/saturnus/docs/commands/19bii.md): 418 functions with their keys, descriptions and examples

## How the Saturn works

- [How the Saturn works](https://ractive.ch/saturnus/docs/saturn.md): The hardware of HP's Saturn calculators for developers: the CPU, the memory and its controllers, the display, the keyboard, the timers and interrupts, the serial port and infrared.
- [The CPU](https://ractive.ch/saturnus/docs/saturn/cpu.md): The Saturn processor: its 4-bit data path, 64-bit registers and their fields, 20-bit addresses, the instruction set in general terms and the clock of each model.
- [Memory](https://ractive.ch/saturnus/docs/saturn/memory.md): How the Saturn reaches ROM, RAM, the hardware registers and the card ports: the memory controllers, their configuration at start-up, the maps of each model and the bank switching of the 48GX and the 49G.
- [The display](https://ractive.ch/saturnus/docs/saturn/display.md): The LCD controller of the Saturn calculators: the 131 × 64 screen, display memory in RAM, the main and menu areas, margins and scrolling, contrast and the annunciators.
- [The keyboard](https://ractive.ch/saturnus/docs/saturn/keyboard.md): How the Saturn calculators read their keys: the key matrix on the CPU's OUT and IN ports, the hardware scan and its interrupt, debouncing, held and released keys, and the ON key on its own line.
- [Timers and interrupts](https://ractive.ch/saturnus/docs/saturn/timers.md): The Saturn's two hardware timers, how the calculator keeps the time with them, the single interrupt and its sources, what can and cannot be masked, and sleeping with SHUTDN.
- [The serial port and infrared](https://ractive.ch/saturnus/docs/saturn/serial.md): The Saturn calculators' UART: the frame, the speeds, the line levels of the wired port, the buffers and interrupts, the infrared link through the same UART, and which model has what.

## Moving files to a real calculator

- [Moving files to a real calculator](https://ractive.ch/saturnus/docs/transfer.md): For owners of a real HP calculator: which cable to use, the Kermit and XModem protocols and their settings, the satx command-line tool, and Files in the app.
- [Cables](https://ractive.ch/saturnus/docs/transfer/cables.md): Which cable connects which HP calculator to a computer: the 48's 4-pin port and its wiring, the 10-pin connector of the 49G and 38G, HP's cables and adapters, USB serial adapters and building a cable yourself.
- [Kermit and XModem](https://ractive.ch/saturnus/docs/transfer/kermit-xmodem.md): The two transfer protocols built into HP's Saturn calculators: which model speaks which, the server and client roles, binary and ASCII transfers, translation modes, the settings in IOPAR, and how to set up a Kermit program on the computer.
- [satx](https://ractive.ch/saturnus/docs/transfer/satx.md): satx, saturnus's command-line tool for moving files between a computer and an HP 48S/SX, 48G/GX or 49G over a serial cable: installing it, starting the calculator's server, and its commands with examples.
- [Files in the app](https://ractive.ch/saturnus/docs/transfer/files.md): Files, the app's view for moving variables between a computer, an emulated calculator and a real one on a serial cable, in Chrome or Edge with Web Serial or in the desktop app; aplets for the 38G, 39G and 40G.

## Optional

- [The app](https://ractive.ch/saturnus/app/): the calculators in the browser, with the same reference in Search