C64 IDE

A native macOS integrated development environment for the Commodore 64 and its extended family of 8-bit machines. Write, build, debug, and run 6502 assembly and BASIC programs, then send them straight to an emulator or real hardware — all without leaving the app.

The source code in this repository is the open-source release of the C64 IDE available from gopherbrokesoftware.com.

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Features

Editing & languages

• 6502/6510 assembly editing with syntax highlighting, built on the ca65 / ld65 toolchain.
• BASIC editing with support for many dialects through a plugin system, including Commodore BASIC V2, 3.5, 4.0 and 7.0, MEGA65 BASIC 65, Simon's BASIC, Vision BASIC, the VIC-20 Super Expander, and Commander X16 BASIC.
• Line-numbered gutter, PETSCII-aware editing, configurable editor fonts, and inline reference tooltips.
• BASIC utilities: renumbering, shortcut expansion, and tokenization support.

Build & run

• One-click Build & Run through the ca65 → ld65 pipeline with a parsed error/warning list.
• Multiple build layouts: standard PRG with a BASIC SYS stub, raw PRG, upper-RAM ($C000) builds, and "assembly to BASIC DATA" generation.
• Assemble to disk bundles and export to disk images.

Debugging

• Source-level debugger with breakpoints, driven through the VICE monitor protocol, that maps machine addresses back to your source lines using assembler debug info.
• 6502 disassembler with C64 ROM symbol resolution.
• Memory map viewer generated from the linker .map file.

Graphics & audio tools

• Sprite editor and character set editor.
• Graphics/bitmap editor and an image format converter.
• Tile map editor with undo support.
• SID editor with a live audio engine for the C64 sound chip.
• Character ROM viewer and PETSCII character map.

Disk & tape images

• Browse and manipulate D64 and D81 disk images.
• Read and write TAP tape images.

Emulators & hardware targets

Send a freshly built program to any of:

• VirtualC64 — embedded, C64.
• VICE — x64sc (C64) and x128 (C128 / BASIC 7.0 / BASIC 3.5).
• xemu (xmega65) — MEGA65 / BASIC 65.
• Ultimate 64 — real hardware over its REST API.
• MEGA65 — real hardware over etherload.

Project management

• Project files (.c64proj) with per-project settings and build configuration.
• Built-in project templates (assembly and BASIC game starters).
• Git integration for version control of your projects.

AI assistance

• Optional Claude integration that is aware of your IDE context, for help while you write code.

Extra utilities

• Number base converter, plugin editor for BASIC dialects, and more.

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Requirements

• macOS (built with Cocoa, AppKit, and SwiftUI).
• The cc65 toolchain (ca65 / ld65) for assembling and linking.
• One or more of the supported emulators or hardware devices to run your programs:
  • VICE (x64sc, x128)
  • xemu (for MEGA65)
  • An Ultimate 64 or MEGA65 for on-hardware execution.

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Building from source

This is an Xcode project written in Swift with a small amount of Objective-C++ (for the embedded VirtualC64 bridge).

1. Clone the repository:

   git clone https://github.com/DNSGeek/C64IDE-OpenSource.git
   cd C64IDE-OpenSource

2. Open the project in Xcode.
3. Build and run the app target.

Install the cc65 toolchain (for example via Homebrew: brew install cc65) so the build pipeline can find ca65 and ld65, then point the IDE at them in its build preferences if they are not on the default search path.

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Repository layout

Directory	Contents
Assembler/	Build pipeline, linker configuration, and assembly-to-data tools
BASIC/	BASIC lexer, parser, code generation, dialect plugins, and tokenizer
Debugger/	Source-level debugger and VICE monitor client
Disassembler/	6502 disassembler and ROM symbol tables
GfxEditor/	Bitmap/graphics editor and image converter
MapEditor/	Tile map editor
SIDEditor/	SID chip editor and audio engine
D64/, TAP/	Disk and tape image handling
VirtualC64/, U64/, MEGA65/	Emulator and hardware target integration
RunInEmulator/	Run-target abstraction and emulator coordination
Project/	Project model, templates, and Git integration
Views/	Editor, tool windows, and UI controllers
SyntaxHighlighting/	Assembly and BASIC syntax highlighters
Claude/	Claude AI integration
Models/	Shared data models and C64 reference data
Resources/	Assets, BASIC dialect plugins, and project templates

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License

This project is licensed under the GNU General Public License, version 2. See the LICENSE file for the full text.

Security

Please see SECURITY.md for the security policy and instructions on how to responsibly report a vulnerability.