fxCGIO !!

Terminal / Console / IO Library for Casio fx-CG50 / fx-CG90

Overview

When I started developing on the Casio fx-CG50 with the excellent fxSDK by Lephenixnoir, I quickly found that every single project needed the same boilerplate code: setting up keyboard polling, managing display output, handling colors, and implementing the same basic I/O loop over and over again. The calculator has a rich 396×224 display and a full keyboard, yet getting a simple printf() to work correctly required non-trivial effort every time.

fxCGIO was created to solve this permanently. It wraps the gint kernel into a clean, Unix-style terminal abstraction, making Casio development feel as natural as writing a program for a Linux terminal. Standard C printf(), scanf() and getchar() all work out of the box — no custom display API needed.

Since then the library has grown to cover multiple color modes (16-color ANSI, 256-color xterm, and 24-bit true RGB), a complete keyboard mapping with SHIFT/ALPHA modifiers and all special keys, a game development API for direct character-grid access (perfect for roguelikes and text adventures), eight bitmap fonts, command history, C++ iostream wrappers, and a full ANSI/VT100 terminal emulator.

The library also targets the PC through a separate CMake build, allowing calculator applications to run on a Linux terminal with full 24-bit color output — tremendously useful for development and debugging without touching the calculator at all.

fxCGIO is based on:

• gint 2.11+ --- https://gitea.planet-casio.com/Lephenixnoir/gint
• fxSDK --- https://gitea.planet-casio.com/Lephenixnoir/fxsdk

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Compatibility and Requirements

Model	Supported
fx-CG50	✔ Yes
PC (Linux x86)	✔ Yes — via pc/ CMake build
fx-CG10 / 20	✔ Yes
fx-CG100	✔ Yes
fx9860G-like	❌ No

Minimum gint version: 2.11 Build system: fxSDK (calculator) or CMake 3.15+ (PC)

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What fxCGIO Provides

Standard Input / Output

Write calculator programs exactly as you would write a standard C or C++ application:

• printf() / puts() / putchar() --- write text to the screen
• scanf() / gets() / getchar() --- read from the keyboard with echo
• std::cout / std::cin --- C++ iostream wrapper for stream operators
• Command history --- UP / DOWN arrows replay the last 20 input lines, just like a real shell

Color System

Three color modes, selectable at runtime, from simple to full true-color:

Mode	Colors	Notes
ANSI 16	16	Standard terminal palette, FXCGIO_COLOR_* constants
xterm 256	256	0–15 ANSI + 216 RGB cube + 24 grey levels
True RGB	16.7M	C_RGB(r, g, b) — 5-6-5 packed, hardware-exact

Keyboard Mapping

All calculator keys are mapped, including multi-modifier combinations. Special keys return negative integer codes (Unicode-safe):

• Printable keys --- Letters, digits, operators via SHIFT / ALPHA modifier state
• Arrow keys --- UP(-2), DOWN(-3), LEFT(-4), RIGHT(-5), HOME(-6), END(-7)
• Function keys --- F1(-8) through F6(-13)
• Shifted arrows --- SHIFT+UP(-14) through SHIFT+RIGHT(-17)
• Alpha arrows --- ALPHA+UP(-18) through ALPHA+RIGHT(-21)
• Shifted F-keys --- SHIFT+F1(-26) through SHIFT+F6(-31)
• Alpha F-keys --- ALPHA+F1(-32) through ALPHA+F6(-37)
• Game polling --- keydown() / keypressed() for non-blocking real-time input

Game Development API

A direct character-grid API makes it easy to build roguelikes, text adventures, or any tile-based application:

• fxCGIO_game_begin() / fxCGIO_game_end() --- frame management
• fxCGIO_game_cols() / fxCGIO_game_rows() --- query grid dimensions at runtime
• fxCGIO_game_put(x, y, ch, fg, bg) --- place a character with foreground/background color
• fxCGIO_game_clear(bg) --- fill the entire grid with a color

Bitmap Fonts

Eight fonts are bundled, covering very different styles and cell sizes:

Font	Size	Grid (cols×rows)	Use case
font5x7	5×7	66 × 28	Default — readable, compact
font8x9	8×9	44 × 22	Larger, easier to read
vga	8×8	44 × 24	Classic VGA CP437 terminal look
microfont	3×5	110 × 40	Maximum density
tinytype	8×8	44 × 24	Small but clean
milifont	5×7	66 × 28	small font retro terminal style
thin	8×8	44 × 24	Elegant thin-stroke variant
fantasy	8×8	44 × 24	Decorative — RPG / game titles

ANSI / VT100 Terminal Emulator

Full escape sequence support for terminal-style applications:

• Cursor positioning: \033[row;colH
• 24-bit foreground/background: \033[38;2;R;G;Bm / \033[48;2;R;G;Bm
• Text attributes: bold, dim, underline, blink, reverse
• Erase sequences: \033[K (erase to end of line), \033[J (erase to end of screen)
• Scroll region control

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Quick Start

C Example

#include <fxCGIO/fxCGIO.h>
#include <stdio.h>

int main(void)
{
    fxCGIO_init();

    printf("Hello, fx-CG50!\n");
    printf("Type something: ");

    char buf[64];
    scanf("%63s", buf);
    printf("You said: %s\n", buf);

    fxCGIO_free();
    return 1;
}

C++ Example

#include <fxCGIO/fxCGIO.hpp>
#include <fxCGIO/cpp/iostream.h>

int main(void)
{
    fxCGIO::init();

    fxCGIO::cout << "Enter a number: ";
    int n;
    fxCGIO::cin >> n;
    fxCGIO::cout << "Doubled: " << n * 2 << fxCGIO::endl;

    fxCGIO::free();
    return 1;
}

or more easy to write :

#include <fxCGIO/fxCGIO.hpp>
#include <fxCGIO/cpp/iostream.h>

using namespace fxCGIO;

int main(void)
{
    init();

    cout << "Enter a number: ";
    int n;
    cin >> n;
    cout << "Doubled: " << n * 2 << endl;

    free();
    return 1;
}

Game API Example

#include <fxCGIO/fxCGIO.h>
#include <fxCGIO/game.h>
#include <gint/keyboard.h>

int main(void)
{
    fxCGIO_init();
    int x = fxCGIO_game_cols() / 2, y = fxCGIO_game_rows() / 2;

    for(;;) {
        clearevents();
        if (keydown(KEY_EXIT)) break;
        if (keydown(KEY_LEFT))  x--;
        if (keydown(KEY_RIGHT)) x++;
        if (keydown(KEY_UP))    y--;
        if (keydown(KEY_DOWN))  y++;

        fxCGIO_game_begin();
        fxCGIO_game_clear(FXCGIO_COLOR_BLACK);
        fxCGIO_game_put(x, y, '@', FXCGIO_COLOR_YELLOW, FXCGIO_COLOR_BLACK);
        fxCGIO_game_end();
    }

    fxCGIO_free();
    return 1;
}

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Build & Install

Calculator Build and install

cd fxcgIO
fxsdk build-cg install

PC Build

cd fxcgIO/pc && mkdir build && cd build
cmake .. && make
# Produces: libfxcgio-pc.a

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TODO List

Short-Term (High Priority)

• Standard C I/O (printf, scanf, getchar, puts)
• 16-color ANSI mode
• 256-color xterm mode
• 24-bit true-color RGB mode
• Complete keyboard mapping (all keys, SHIFT/ALPHA modifiers)
• Negative-integer special key codes (Unicode-safe)
• Command history (20 entries)
• Game API (direct character grid)
• Eight bitmap fonts
• Full ANSI / VT100 escape sequences
• C++ iostream wrapper (std::cout / std::cin)
• PC build — Linux terminal with true-color ANSI output
• Windows / WSL PC build support
• fx-CG50 USB serial passthrough for remote debugging

Long-Term (Possible Future Work)

• Soft keyboard overlay (on-screen virtual keyboard)
• Mouse cursor emulation via arrow keys
• Font editor / import tool
• Compressed font format for larger character sets

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Version History

Version 0.8

• Initial public release
• Standard C I/O (printf, scanf, getchar, puts)
• 16-color ANSI color mode
• Basic keyboard mapping (letters, digits, arrows, F-keys)
• Default font (5×7)

Version 0.9

• Added 256-color xterm mode
• Added 24-bit true-color C_RGB() support
• Extended keyboard mapping: SHIFT+arrow, ALPHA+arrow, SHIFT/ALPHA+F-keys
• Added command history (up to 20 lines)
• Added C++ iostream wrapper

Version 1.0

• Added Game API (fxCGIO_game_begin/end/put/clear/cols/rows)
• Added 7 additional bitmap fonts (vga, microfont, tinytype, milifont, thin, fantasy, font8x9)
• Full ANSI/VT100 escape sequence support
• Line discipline improvements (backspace, echo toggle)

Version 1.1

• PC build via separate CMake configuration
• PC keyboard driver: termios raw mode + ANSI CSI/SS3 escape decoder
• PC renderer: 24-bit ANSI output, dirty-cell batching, consecutive-cell optimisation
• Unified special key codes between calculator and PC builds

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Documentation

Full documentation is available in the docs/ directory:

• Installation Guide
• Getting Started
• Tutorial
• API Quick Reference
• Color System Guide
• Code Examples
• FAQ

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Disclaimer

This software is a Work in Progress and is provided "as is", without warranty of any kind. Although extensive testing has been performed, unexpected behavior may occur — especially on edge-case keyboard combinations or in non-standard terminal environments on the PC build.

Please:

• Test new color and keyboard features on your specific calculator model
• Report bugs with the simplest possible reproducer
• Check gint version compatibility before upgrading

The author cannot be held responsible for any issues caused by the use of this library.

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Credits

Thanks to Lephenixnoir for his extraordinary work on gint and fxSDK, and for his patience in answering every question about the SH4 internals.

Thanks to the Planète Casio community.

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