BASIC256

BASIC256 is a small, approachable language that lets a beginner gradually grow into graphics, simulation, games and systems programming.

BASIC256 is a free, open-source BASIC programming environment for beginners and hobbyists. It is the actively maintained continuation of the original BASIC256, modernized for Windows, Linux, macOS and the Web while retaining compatibility with existing BASIC256 programs.

• 🌐 Homepage
• 📚 Documentation
• ▶️ Run BASIC256 in your browser
• 💾 Download releases

• Designed specifically for beginners and hobbyists
• Simple BASIC syntax
• Immediate graphics and sound
• Cross-platform desktop and Web versions
• Many example programs to learn from and experiment with
• Free and open source under GPLv3+

No installation is needed. The WebAssembly version provides the full editor and interpreter directly in your browser.

▶ Run BASIC256

For example:

# bubbles.kbs — random transparent colorful circles
clg
fastgraphics

for i = 1 to 500
    color rgb(int(rand*256), int(rand*256), int(rand*256), 100+int(rand*150))
    circle rand*graphwidth, rand*graphheight, rand*40
    refresh
next i

The browser version supports several useful URL modes:

For example:

• https://run.basic256.org/?run=Mandelbrot-256&mode=graph
• https://run.basic256.org/?run=BubbleUniverse_variations

This makes the Web version useful not only for learning, but also for sharing and embedding BASIC256 programs.

Copy the WASM build to any static host served over HTTPS, and send these two headers that the multithreaded build relies on:

Cross-Origin-Opener-Policy: same-origin
Cross-Origin-Embedder-Policy: require-corp

With those in place the page loads in a single pass — no reload — and the bundled coi-serviceworker helper (only needed because GitHub Pages can't send those headers itself) is no longer required.

The browser runs inside a sandbox, so some desktop features are unavailable:

• Files created by a running program exist only for the current browser session.
• Programs in the editor persist across refreshes.
• SOUND, SAY and related features use browser audio/speech support and could be unavailable.
• TCP networking, SYSTEM, serial ports, database/SQL and printer commands are unavailable.
• Large fractals and simulations generally run slower than on the desktop.
• Media such as SOUNDLOAD and IMGLOAD can be loaded from paths relative to the Web page, subject to normal browser CORS rules.

• Toolkit Module: New Modules/toolkit.kbs (INCLUDE "toolkit.kbs") draws a classic-style interface on the graphics output: buttons, checkboxes, radio buttons, sliders, spin boxes, tabs, group boxes, drawing fields and editable text fields, each with a hit-test function for mouse clicks. CALL tk_help() lists them all.
• New Examples: Examples/GUI-Demo shows each toolkit element at work, and a series of Falling Sand programs builds up the final program step by step. Examples/Fun adds balgame256.kbs, a ball-catching game played with the mouse, and FallingLetters.kbs, a falling-letters rain effect.
• Mouse Clicks: CLICKX, CLICKY and double-clicks now work across a graphics window scaled up by GRAPHSIZE or zoomed from the View menu, reporting the graphics pixel under the pointer. A negative scale shows the whole picture turned round.

• ARRAYADD Added: Appends to the end of an array — a value to a 1D array, a row to a 2D array (ARRAYADD points, x, y) — and turns an empty variable into an array, so tables can be built in a loop without DIM.
• Module Prefixes (breaking): Every routine in the bundled modules now carries its module's prefix — ma_ for math.kbs, tu_ for turtle.kbs, tk_ for toolkit.kbs — and each module has a help routine (ma_help, tu_help, tk_help). Programs from 2.3.0 must use the new names (e.g. ma_hypot, tu_forward).
• Number Range: A whole-number literal too big for 64 bits is now reported as "Number too large" at compile time.

• Dark Theme: View/Theme/Follow System turns the whole IDE dark when the OS is in dark mode — menus, toolbars, docks, dialogs and the Variable Watch window included. Windows 10 uses the Fusion style while dark.
• Save As: Opens in the program's own folder with its name filled in. Examples are never overwritten — saving one asks for a new name, and the Examples folder cannot be chosen as a save location.
• Overwrite Warning: New preference, Warn when overwriting an existing file (on by default). Untick it to let Save write straight back to the program's own file. The old Automatically save program when it is successfully run option has been removed.

• Raspberry Pi: The Pi archive now includes the TestSuite and the benchmark.
• Windows Installer: The installer and uninstaller detect a running BASIC256 and offer Retry/Cancel instead of failing on basic256.exe.

• File Access Prompts: Accessing files/folders outside the program's root directory now triggers a user confirmation prompt (OPEN, KILL, MKDIR, IMGSAVE, DBOPEN, SQL targets, etc.).
• Loopback Network Default: NETLISTEN now listens exclusively on 127.0.0.1 by default. Network access can be enabled in Preferences/Advanced.
• Directory Commands: MKDIR restored (works without SYSTEM). RMDIR has been permanently removed for safety.

• TEXTSCREEN Added: Convert the Text Output window into a true grid-based character screen with fixed dimensions and optional square cells (TEXTSCREEN cols, rows [, square]).
• Console Controls: LOCATE positions the cursor for in-place overwriting. Added TEXTCOLOR, TEXTBACKGROUND, TEXTFONT, and TEXTCHAR().

• Color & Sprites: Added HSV(h, s, v [, a]) color function, 3D Noise support via NOISE(x, y, z), and SPRITETEXT to render text directly onto sprites.
• Sprite Scaling: SPRITEW and SPRITEH now accurately report transformed dimensions.
• Coordinate Mapping: IMGLOAD, GETSLICE, and PUTSLICE now respect custom WINDOW coordinates.

• Array Sorting: New built-in SORT statement for 1D and 2D arrays (SORT array [, col] [, ASCENDING|DESCENDING] [, IGNORECASE]).
• Subroutine Pass-by-Reference Fix: Subroutines declaring ref() parameters now correctly modify the caller's target variable passed without an explicit ref() wrapper.
• Syntax Improvements: Fixed an issue where statements without arguments followed by a colon (e.g., NEXT:, CLS:) were misidentified as labels.

• Raspberry Pi: Fixed missing SQLite driver error for DBOPEN.
• Benchmarking & Examples: Added TestSuite/Benchmark utility and a new SQLite console demo (Examples/DataBase/GamesDB.kbs).

• Gallery Page There is now a Gallery page on basic256.org where you can run the examples directly in a pop-up Browser window.

• Execution Speedup: Overall execution is 20–25% faster due to optimized runtime value handling across arithmetic, drawing, and array operations.
• Array Optimization: Arrays use ~50% less memory. Whole-array operations (DIM, REDIM, array copying, MAT statements) run 3–5x faster.

• Vector Operators: Added DOT, CROSS, NORM(v), and UNIT(v) for vector arithmetic on standard 1D/2D arrays.
• Matrix Operators: New MAT statement adds following matrix operations: MUL, ADD, SUB, INV and TRN.
• Turtle Graphics Module: Added Modules/turtle.kbs (INCLUDE "turtle.kbs") for turtle-style relative drawing (t_forward, t_left, t_goto, etc.).
• FRAMERATE Control: New FRAMERATE fps statement locks drawing loops to a target frame rate (e.g., FRAMERATE 60), automatically adjusting for system speed differences.
• OpenSimplex noise: Added NOISE for smooth, repeatable OpenSimplex noise (ideal for terrain, clouds, and paths). Tied to SEED for deterministic output.

• Unlimited File Size: Removed the ~5,000-line program length limit (including INCLUDE files).
• Improved PAUSE: Accurate millisecond-level precision across all platforms; instantly interruptible by clicking Stop.
• Syntax Adjustments: MOD is now a case-insensitive keyword (reserved word).

• WINDOW Statement: Set custom coordinate systems and axis orientations (WINDOW x1, y1, x2, y2), with middle-point centering or graph paper orientation. MOUSEX, MOUSEY, PIXEL, etc. adapt automatically.
• Subpixel Drawing: Graphics statements (PLOT, LINE, CIRCLE, RECT, TEXT, etc.) now accept fractional coordinates for precision positioning.

• Multi-line Literals: Array and map literals ({ ... }) can now span multiple lines with inline comments (#), allowing clean table and matrix layouts.

• Faster Execution: Arithmetic-heavy loops run roughly 2x faster due to internal memory reuse for intermediate values and reduced interpreter step overhead. Gains are highest in the WASM/browser build.

• Session Persistence: Editor state, open tabs, active selection, and file names now auto-persist in the browser across tab closes, page refreshes, or browser restarts.

• Windows 11 Scaling: Menu bar titles (File, Edit, View, etc.) now properly scale and adjust spacing based on system text size settings.
• Streamlined Windows Installer: Removed the redundant standalone Microsoft VC++ Redistributable installer file (still bundled within the main installer when needed).
• Updated Links: Updated Help/About to include the main site (https://basic256.org) alongside the documentation portal.

Major Update: BASIC-256 has migrated to Qt 6, enabling WebAssembly (WASM) browser execution, modern UI features, and relicensing to GPL v3 or later.

• Qt 6 & WASM Support: Ported codebase to Qt 6 and CMake. You can now run BASIC-256 directly in a web browser!
• UI Themes & Layout: Added Light, Dark, and Follow System themes (View/Theme). Window maximizing and docking now preserve balanced pane proportions.
• New MAXIMIZE Statement: Programmatically maximize (MAXIMIZE 1) or restore (MAXIMIZE 0) the IDE window.
• Mascot & Visuals: Introduced new program logo, transparent app icons across all platforms, and the BitBot mascot.
• Built-in Modules: INCLUDE statements now directly access bundled libraries (e.g., include "math.kbs") in the browser.

• Mobile Audio & Touch: Full audio/speech support on iPad/iPhone and touch-driven interaction for browser demos.

• New CLI Flags: -f (fullscreen run), -s (silent mode with suppressed screen output for background processing/testing), and -g (shows graphics pane only).
• macOS Sequoia: Added official Intel macOS support (requires macOS 15+).

• New Documentation Portal: Replaced legacy docs with a modern Docusaurus site at doc.basic256.org (accessible via F1 or Help/Online Help).
• Documented Features: Added docs for ELLIPSE, SETGRAPH, GETARRAYBASE, optional LET, bit-shifts (<<, >>), and compound assignments (&=, ;=).

The desktop application provides the familiar BASIC256 three-pane environment:

• Editor — write and edit BASIC programs.
• Text Output — program output and console-style interaction.
• Graphics Output — immediate drawing and animation.

The same BASIC256 programs can therefore be developed on the desktop and shared through the Web version.

Get the latest builds from the Releases page.

The supplied macOS applications are ad-hoc signed rather than notarized. If Gatekeeper reports that the application is damaged, try:

xattr -cr /Applications/basic256.app

For older macOS versions, the original Qt5-based BASIC-256 2.0.0.11 may be an alternative, or BASIC256 can be built from source against Qt 5.15.

The Raspberry Pi build is intended for modern Raspberry Pi Linux installations. Speech support may require speech-dispatcher to be installed separately.

BASIC256 can also run programs from a terminal:

For example:

basic256 -g Mandelbrot-256.kbs
basic256 -f -t Zork256.kbs
basic256 -s TestProgram.kbs

The repository contains a large collection of example programs covering graphics, games, mathematics, simulations, sound and other BASIC256 features.

The original minimal examples from BASIC256 2.0.0.11 are preserved under:

Examples/Original_Examples/

Additional examples can be found at Manuel Santos' BASIC256 blog.

BASIC256 includes 3 small standard libraries in the Modules folder. Every function and subroutine in a module starts with two letters and an underscore naming the module (ma_, tu_, tk_), which keeps its names apart from a program's own and from those of the other modules. Each module also has a help routine that prints what is in it.

1. Modules/math.kbs

Use it with:

include "math.kbs"
call ma_help()

It currently provides functions including:

ma_minarr, ma_maxarr, ma_sumarr, ma_avgarr, ma_sign, ma_min, ma_max, ma_lerp, ma_hypot, ma_atan2, ma_clamp, ma_map, ma_wrap, ma_dist, ma_fmod, ma_cbrt, ma_randint and ma_gaussian.

These are implemented as BASIC256 code rather than built-in language commands, keeping the language itself small while making common operations convenient.

2. Modules/turtle.kbs

Use it with:

include "turtle.kbs"
call tu_help()

This provides turtle logic with following subroutines:

tu_reset, tu_goto, tu_home, tu_forward, tu_backward, tu_right, tu_left, tu_setheading, tu_penup, tu_pendown, tu_x, tu_y, tu_getheading, tu_getpen
and short-codes tu_fw, tu_bw, tu_pu, tu_pd, tu_r, tu_l

3. Modules/toolkit.kbs

Use it with:

include "toolkit.kbs"
call tk_help()

This draws a classic-style interface on the graphics output. Each element has a subroutine that draws it and a function that tells whether a mouse click landed on it; the program keeps the state and redraws an element when it changes:

tk_button / tk_buttonhit, tk_checkbox / tk_checkhit, tk_radio / tk_radiohit, tk_slider / tk_sliderhit / tk_sliderval, tk_spinner / tk_spinhit, tk_drawtabs / tk_tabhit, tk_grouper, tk_drawing / tk_drawhit
and the text field tk_textfield / tk_texthit, with tk_textcaretat, tk_textedit$ and tk_textcaret for clicking, typing and moving the caret.

The programs in Examples/GUI-Demo show each element at work.

Upgrading from 2.3.0: the module prefixes are new in 2.3.1. A program that still calls the old names (sumarr, hypot, t_forward, ...) stops with an error; rename the calls to ma_sumarr, ma_hypot, tu_forward and so on. Two names change by more than the prefix: remap is now ma_map, and fround has been removed.

Detailed build instructions are in:

• COMPILING.txt
• COMPILING_RaspberryPI.txt

The project uses CMake, Qt6 and GitHub Actions, with builds for Windows, Linux, Raspberry Pi, macOS and WebAssembly.

BASIC256 began as KidBasic in 2006, created by Ian Paul Larsen and later maintained by James Reneau and other contributors through SourceForge. The original project eventually became BASIC256 and reached version 2.0.0.11.

This repository is a continuation of that project. It started from the 2.0.99.10.2 development branch with the goal of modernizing the codebase while preserving its educational character and compatibility.

The major development steps have been:

• 2.1.0 — modern build system, portability and new platforms.
• 2.1.1 — significant performance improvements and Web persistence.
• 2.2.0 — new language features, mathematics, graphics capabilities and further performance improvements.
• 2.3.0 — safer system access and enhanced text-console capabilities.
• 2.3.1 — the GUI toolkit module, prefixed module names, ARRAYADD, a dark IDE that follows the system theme, and safer saving.

The original copyright notices have been retained.

Development continues with an emphasis on education, portability, performance and compatibility.

Current areas of interest include:

• More distribution packages
• More standard modules
• More and better examples
• Educational tutorials
• New language features where a module would be too slow
• Continued improvements to documentation and deployment

BASIC256 is a hobbyist/open-source project and contributions are welcome.

You can help by:

• Reporting bugs
• Improving documentation
• Writing examples
• Translating documentation
• Testing releases
• Improving tutorials
• Submitting pull requests

Use:

• Issues for bugs and feature requests
• Discussions for questions, ideas and projects
• Discord to join the community

BASIC256 is distributed under the GNU General Public License version 3 or later (GPLv3+).

The original project used GPLv2 "or (at your option) any later version", allowing this continuation to move to GPLv3+. See license.txt for the full license.

Two components retain their compatible original licenses:

• src/core/md5.cpp / md5.h — RSA Data Security code adapted by Frank Thilo
• src/gui/LineNumberArea.cpp / .h — BSD-licensed code from the Qt examples

BASIC256 is maintained as a hobbyist/open-source project with the help of modern AI development tools. Contributions to the code, examples, documentation and translations are especially welcome.